Engine conditioning apparatus and method

• US 5,833,765 A
• Filed: 10/26/1995
• Issued: 11/10/1998
• Est. Priority Date: 09/22/1993
• Status: Expired due to Fees

• Current Assignee: Kyung A.E. Kim, Robert A. Doty
• Original Assignee: Robert A Flynn, Robert E. Flynn
• Inventors: Flynn, Robert E., Flynn, Robert A.
• Primary Examiner(s): Stinson, Frankie L.
• Application Number:
  US08/547,730
• Time in Patent Office: 1,111 Days
• Field of Search: 134/167 R, 134/166 R, 134/57 R, 134/56 R, 134/113, 134/169 A, 134/22.12, 134/22.18, 134/169 R, 123/198 A
• US Class Current: 134/22.12
• CPC Class Codes: F02B 77/04 Cleaning of, preventing corrosion or erosion in, or preventing unwanted deposits in, combustion engines cleaning of fuel injection apparatus F02M65/00
• CPC Class Codes: F02F 2007/0092 Transparent materials
• CPC Class Codes: F02M 65/008 of injectors only

Abstract

Carbon deposits and related residue are removed from he internal surfaces of components of an internal combustion engine, particularly the fuel ports of a carbureted engine and the injection nozzles of a fuel injection engine, by circulating an engine conditioning fuel, through the engine utilizing a conditioning fuel pump, preferably driven by a fluid driven motor, for pumping conditioning fuel to the engine. The conditioning apparatus can detect leakage of the fuel pressure regulator of a fuel injected engine and can operate in both a one-line mode in which conditioning fuel flows one way from the apparatus to the engine and a two-line mode wherein the conditioning fuel is recirculated through the engine and conditioning apparatus. A preferred embodiment provides diagnostic features for checking the conditioning apparatus and certain engine components. These include a by-pass conduit between a flowmeter input side and an engine pressure regulator, check valve means to test opening pressure of the pressure regulator, a pressure control valve to restrict flow to reduce pressure below a set pressure regulator opening pressure to indicate leakage, a shut-off valve closable to provide indication of static system pressure produced by the engine fuel pump, and openable to provide indication of flow rate produced by the fuel pump.

Claims

1. Engine conditioning apparatus for cleaning internal carbon deposits from an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, and excess fuel return means for conducting said excess fuel from said input means, said conditioning apparatus comprising:

a fuel handling system including a conditioning fuel tank for containing an engine conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line including selectable flow path means and having one end for connection to said tank and an opposite end for connection to said engine fuel infeed means, an excess fuel return line having one end connected to said tank and an opposite end for connection to said engine excess fuel return means, and a pump having an inlet connected to said tank and an outlet connected to said one end of said delivery line for pumping conditioning fuel from said tank through said delivery line,

means for driving said pump,

means providing a first flow path connecting said tank and pump outlet in parallel with said pump and including a check valve which permits flow through said flow path only in a direction from said tank to said delivery line,

means providing a second flow path connecting said tank and pump outlet and including a check valve which opens to permit flow through said second path only in the direction of said tank, and a shutoff valve which may be opened to permit fuel flow through said second flow path and closed to block fuel flow through said

second flow path, and wherein

said selectable flow path means comprises (a) first and second selectable flow paths through which conditioning fuel may flow from said tank to the engine, (b) a selector valve having an inlet connected to said pump outlet, a first outlet connected to said first selectable flow path, a second outlet connected to said second selectable flow path, and means for selectively connecting said valve inlet to either valve outlet, (c) a flow meter in said first selectable flow path having an inlet connected to said first selector valve outlet, and an outlet, and (d) a check valve in said first selectable flow path in series with said flowmeter which opens to permit fuel flow through said first selectable flow path only in a direction from said flowmeter inlet to said flowmeter outlet and in response to a predetermined pressure differential across the last mentioned check valve.

2. Engine conditioning apparatus according to claim 1, wherein:

said means for driving said pump comprises a fluid driven motor having a driving fluid inlet, a fluid supply line having one end connected to said motor inlet and an opposite end for connection to a source of motor driving fluid and a valve in said fluid supply line for controlling driving fluid flow to said motor.

3. Engine conditioning apparatus according to claim 2, including:

a quick disconnect coupling on said opposite end of said delivery line for connection to said engine fuel infeed means,

a quick disconnect coupling on said opposite end of said excess fuel return line for connection to said engine excess fuel return means, and

a quick disconnect coupling on said opposite end of said fluid supply line for connection to a source of motor driving fluid.

4. In combination:

(a) an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, and excess fuel return means for conducting said excess fuel from said input means, and (b) an engine conditioning apparatus for removing internal carbon deposits from said engine, and wherein said conditioning apparatus comprises;

a fuel handling system including a conditioning fuel tank for containing an engine conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line including selectable flow path means and having one end for connection to said tank and an opposite end connected to said engine fuel input means, an excess fuel return line having one end connected to said tank and an opposite end connected to said engine excess fuel return means, and a pump having an inlet connected to said tank and an outlet connected to said one end of said delivery line for pumping conditioning fuel from said tank through said delivery line,

means for driving said pump,

means providing a first flow path connecting said tank and pump outlet in parallel with said pump and including a check valve which permits flow through said flow path only in a direction from said tank to said delivery line,

means providing a second flow path connecting said tank and pump outlet and including a check valve which opens to permit flow through said second path only in the direction of said tank, and

a shutoff valve which may be opened to permit fuel flow through said second flow path and closed to block fuel flow through said second flow path, and wherein

said selectable flow path means comprises (a) first and second selectable flow paths through which conditioning fuel may flow from said tank to the engine, (b) a selector valve having an inlet connected to said pump outlet, a first outlet connected to said first selectable flow path, a second outlet connected to said second selectable flow path, and means for selectively connecting said valve inlet to either valve outlet, (c) a flow meter in said first selectable flow path having an inlet connected to said first selector valve outlet, and an outlet, and (d) a check valve in said first selectable flow path in series with said flowmeter which opens to permit fuel flow through said first selectable flow path only in a direction from said flowmeter inlet to said flowmeter outlet and in response to a predetermined pressure differential across the last mentioned check valve.

5. In combination:

an internal combustion engine having a fuel system for supplying fuel to the engine, and an engine conditioning apparatus for removing internal carbon deposits from the engine, and wherein said conditioning apparatus comprises;

a fuel handling system including a tank for containing a combustible engine conditioning fuel capable of removing internal carbon deposits from the engine, a conditioning fuel delivery line having one end connected to said tank and an opposite end connected to the engine fuel system, and a conditioning fuel pump for effecting conditioning fuel flow from said tank to the engine through said fuel delivery line,

a fluid driven motor connected to said pump for driving the pump and having a fluid inlet for receiving a driving fluid for driving said motor, and

a fluid supply line having one end connected to said motor inlet, an opposite end for connection to a remote source of said motor driving fluid, and a length which permits placement of said conditioning apparatus at a sufficient distance from said source to prevent accidental ignition of said combustible engine conditioning fuel by any electrical activity associated with said source, wherein said pump has an inlet connected to said tank and an outlet connected to said delivery line, and said apparatus further includes means providing a first flow path connecting said tank and pump outlet and including a check valve which permits flow through said flow path only in the same direction as flow through said pump, and means providing a second flow path connecting said tank and said delivery line and including a check valve which permits flow through said second flow path only in the direction of said tank, and a shut-off valve which can be selectively closed and opened by an operator of the apparatus to selectively block and permit flow through said second flow path.

6. In combination:

(a) an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, an engine fuel pressure regulator and excess fuel return means for conducting said excess fuel from said input means, and (b) an engine conditioning apparatus for removing internal carbon deposits from the engine, and wherein said conditioning apparatus comprises;

a fuel handling system including a conditioning fuel tank for containing an engine conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line connecting said tank to said engine fuel infeed means, an excess fuel return line connecting said tank to said engine excess fuel return means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

means providing a flow path connecting said tank and said delivery line and including a check valve which permits flow through said flow path only in the direction of said tank, and a shut-off valve which can be selectively closed and opened by an operator of the apparatus to selectively block and permit flow through said flow path, and

a check valve and flowmeter in the flow Path means and adapted to provide indication of opening pressure of said check valve by a pressure gauge downstream of the fuel infeed means to determine correctness of the check valve opening pressure in response to predetermined pressure across the valve.

7. In combination:

(a) a fuel injected internal combustion engine including fuel injectors, a fuel infeed line for conducting fuel to said injectors, a fuel return line for conducting unused fuel from said injectors, and a fuel pressure regulator in said return line, and (b) an engine conditioning apparatus for removing internal carbon deposits from the engine, and wherein said conditioning apparatus comprises;

fuel handling means for conducting an engine conditioning fuel to said engine including first and second parallel flow paths connected to said fuel infeed line,

a selector valve for selectively closing either flow path and directing said fuel to the engine through the other flow path,

a flowmeter in one flow path for measuring the fuel flow rate though said one flow path, and

a normally closed check valve in said one path which opens to permit fuel flow to the engine through said one flow path in response to a predetermined pressure differential across the check valve.

8. A method of operating a fuel injected internal combustion engine having fuel injectors, a fuel infeedl line for conducting fuel to said injectors, a fuel return line for conducting unused fuel from said injectors, and a fuel pressure regulator in said return line having a certain rated cracking pressure at which the regulator is designed to crack open, comprising the steps of:

(a) supplying fuel to said fuel infeed line at a pressure just slightly less than said rated cracking pressure, whereby the fuel flow to said fuel infeed means is injected into the engine through said fuel injectors, and

(b) measuring fuel flow to said fuel infeed line with a flow metering means which normally indicates a certain flow rate under the condition set forth in step (a) above, whereby a flow rate indication different from said certain flow rate under the conditions of step (a) indicates leakage of the pressure regulator, and cracking open of the pressure regulator may be determined by gradually increasing the fuel pressure to the engine and noting the change in the flow rate indication of the flow metering means in response to cracking of the regulator.

9. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, a fuel pump for supplying fuel to said fuel input means, an engine fuel pressure regulator, said conditioning apparatus comprising:

a fuel handling system including a conditioning fuel tank for conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line for connecting said tank to said engine fuel infeed means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

a flow meter and a pressure gauge in the conditioning fuel delivery line to the engine,

said conditioning apparatus including a diagnostic by-pass conduit between the input side of the flowmeter and said vehicle pressure regulator, and

shut-off valve means downstream of the flow meter, said shut-off valve means being closable to block flow through said fuel handling system to provide indication by said pressure gauge of static fuel system pressure produced by said engine fuel pump, and said shut-off valve means being openable to allow flow through said fuel handling system to provide indication by the flowmeter of flow rate produced by said vehicle fuel pump, and to indicate whether there is flow restriction in the system.

10. An engine conditioning apparatus according to claim 9, wherein said shut-off valve means comprises a manually operable mechanical valve openable for flow of conditioning fuel to the conditioning fuel tank.

11. An engine conditioning apparatus according to claim 9, and further including:

a check valve adjacent to the flowmeter in said fuel delivery line to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined pressure differential.

12. An engine conditioning apparatus according to claim 9 and further including:

valve means closable to block flow from the engine pressure regulator and divert such flow to the vehicle fuel tank for detection of any leak in the fuel handling system with the engine off and with relatively high pressure in the system, whereby detection of system leakage is observed visually or by pressure drop indication by the pressure gauge.

13. An engine conditioning apparatus according to claim 9 and further including:

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a lower pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lower pressure.

14. An engine conditioning apparatus according to claim 9 and further including excess fuel return means to conduct excess fuel from said fuel input means to the conditioning fuel tank.

15. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a rueql system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, an engine fuel pressure regulator, said conditioning apparatus comprising:

a fuel handling system including a conditioning fuel tank for conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line for connecting said tank to said engine fuel infeed means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

a flow meter and a pressure gauge in the conditioning fuel delivery line to the engine,

said conditioning apparatus including a diagnostic by-pass conduit between the input side of the flowmeter and said vehicle pressure regulator, and

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a lower pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lower pressure.

16. Engine conditioning apparatus according to claim 15, wherein said pressure control valve is a needle valve having a manually operable pressure control knob.

17. An engine conditioning apparatus according to claim 15, and further including:

a check valve adjacent to the flowmeter in said fuel delivery line to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined pressure differential.

18. An engine conditioning apparatus according to claim 15, and further including excess fuel return means to conduct excess fuel from said fuel input means to the conditioning fuel tank.

19. An engine conditioning apparatus according to claim 15, and further including:

valve means closable to block flow from the engine pressure regulator and divert such flow to the vehicle fuel tank for detection of any leak in the fuel handling system with the engine off and with relatively high pressure in the system, whereby detection of system leakage is observed visually or by pressure drop indication by the pressure gauge.

20. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, and fuel pump means for supplying fuel to said fuel input means, an engine fuel pressure regulator, said conditioning apparatus comprising:

a fuel handling system including a conditioning fuel tank for conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line for connecting said tank to said engine fuel infeed means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

a flowmeter and a pressure gauge in the conditioning fuel delivery line to the engine,

said conditioning apparatus including a diagnostic by-pass conduit between the input side of the flowmeter and said vehicle pressure regulator, and

a check valve adjacent to the flowmeter in said fuel delivery line to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined pressure differential.

21. An engine conditioning apparatus according to claims 20, wherein said check valve has a predetermined flow restriction according to the cracking opening pressure of the pressure regulator.

22. An engine conditioning apparatus according to claim 20, and further including excess fuel return means to conduct excess fuel from said fuel input means to the conditioning fuel tank.

23. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, an engine fuel pressure regulator, said conditioning apparatus comprising:

a fuel handling system including a conditioning fuel tank for conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line for connecting said tank to said engine fuel infeed means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

a flow meter and a pressure gauge in the conditioning fuel delivery line to the engine,

said conditioning apparatus including a diagnostic by-pass conduit between the input side of the flowmeter and said vehicle pressure regulator, and

valve means closable to block flow from the engine pressure regulator and divert such flow to the vehicle fuel tank for detection of any leak in the fuel handling system with the engine off and with relatively high pressure in the system, whereby detection of system leakage is observed visually or by pressure drop indication by the pressure gauge.

24. An engine conditioning apparatus according to claim 23, and further including:

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a lower pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lower pressure.

25. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump, and

a check valve adjacent to the flowmeter in said flow path means to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined threshold pressure differential.

26. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump,

a check valve adjacent to the flowmeter in said flow path means to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined threshold pressure differentials and

shut-off valve means disposed downstream of the flowmeter, said shut-off valve means being closable to block flow through said fuel handling system to provide indication by said pressure gauge of static fuel system pressure produced by said engine fuel pump, and said shut-off valve means being openable to allow flow through said fuel handling system to provide indication by the flowmeter of flow rate produced by said vehicle fuel pump, and to indicate whether there is flow restriction in the system.

27. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump,

a check valve adjacent to the flowmeter in said flow path means to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined threshold pressure differential, and

valve means closable to block flow from the engine pressure regulator and divert such flow to the vehicle fuel tank for detection of any leak in the fuel handling system with the engine off and with relatively high pressure in the system, whereby detection of system leakage is observed visually or by pressure drop indication by the pressure gauge.

28. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump, and

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lowered pressure.

29. Engine conditioning apparatus according to claim 28, wherein said pressure control valve is a needle valve having a manually operable pressure control knob.

30. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow Path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means, said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump,

a check valve adjacent to the flowmeter in said flow path to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined pressure differential, and

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lowered pressure.

31. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump,

a pressure control valve operable to restrict flow to the engine to progressively reduce pressure indicated by said gauge to a pressure below the correct set opening cracking pressure of the engine pressure regulator to provide indication by the flowmeter of engine pressure regulator leakage by indicating flow at such lowered pressure, and

shut-off valve means downstream of the flowmeter, said shut-off valve means being closable to block flow through said fuel handling system to provide indication by said pressure gauge of static fuel system pressure produced by said engine fuel pump, and said shut-off valve means being openable to allow flow through said fuel handling system to provide indication by the flowmeter of flow rate produced by said vehicle fuel pump, and to indicate whether there is flow restriction in the system.

32. Engine conditioning apparatus for cleaning carbon deposits from an internal combustion engine having a fuel system for supplying fuel to the engine and an engine fuel pressure regulator, said conditioning apparatus comprising:

a conditioning fuel handling system including a conditioning fuel tank, conditioning fuel flow path means for conducting conditioning fuel from said tank to the engine, and a pump to effect conditioning fuel flow from said tank through said flow path means,

said flow path means comprising a flowmeter and a pressure gauge downstream of said pump, and having an inlet connected with said pump, and

shut-off valve means disposed downstream of the flowmeter and upstream of the conditioning fuel tank, said shut-off valve means being closable to block flow through said flow path to provide indication of static fuel system pressure at said pressure gauge, and said shut-off valve means being openable to provide indication by said flowmeter of rate of flow through said flow path to determine whether or not there is flow restriction and whether said pressure regulator is defective.

33. Engine conditioning apparatus according to claim 32, wherein said shut-off valve means comprises a manually operable mechanical valve openable for flow of conditioning fuel to the conditioning fuel tank.

34. An engine conditioning apparatus according to claim 32, and further including:

check valve adjacent to the flowmeter in said flow path line to provide indication by said pressure gauge of the opening cracking pressure of the pressure regulator by the flowmeter to determine correctness of the opening pressure by the check valve opening in the direction of flow in response to a pressure differential across the valve at least equal to a predetermined pressure differential.

35. An engine conditioning apparatus according to claim 32, and further including:

valve means closable to block flow from the engine pressure regulator and divert such flow to the vehicle fuel tank for detection of any leak in the fuel handling system with the engine off and with relatively high pressure in the system, whereby detection of system leakage is observed visually or by pressure drop indication by the pressure gauge.

36. In combination:

(a) an internal combustion engine having a fuel system including fuel input means through which fuel is introduced into the engine, fuel infeed means for supplying fuel to said fuel input means, an engine fuel pressure regulator and excess fuel return means for conducting said excess fuel from said input means, and (b) an engine conditioning apparatus for removing internal carbon deposits from the engine, and wherein said conditioning apparatus comprises;

a fuel handling system including a conditioning fuel tank for containing an engine conditioning fuel capable of removing said carbon deposits, a conditioning fuel delivery line connecting said tank to said engine fuel infeed means, an excess fuel return line connecting said tank to said engine excess fuel return means, and a conditioning fuel pump for effecting conditioning fuel flow from said tank through said fuel delivery line,

means providing a flow path connecting said tank and said delivery line and including a check valve which permits flow through said flow path only in the direction of said tank, and a shut-off valve which can be selectively closed and opened by an operator of the apparatus to selectively block and permit flow through said flow path, and

a pressure control valve and pressure gauge in said flow path and adapted for reducing pressure to a pressure below a set pressure of said pressure regulator to provide indication by a flowmeter of engine pressure regulator leakage.