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Vehicle: Dodge Grand Caravan 1995 FWD MPFI 3.8L
Problem: Hard start when hot, stalling while driving.
History of the problem: Long one. Available upon request.
Observations: The fuel pressure does not hold with key off, it immediately drops to 0. But it holds much better when engine is cold and the return line is pinched either right after fuel rail or near the tank. Fuel pressure is close to normal when engine is running. Fuel pressure regulator passes the test with pulling out the vacuum line - the fuel pressure increases by 10 PSI. No smell of gas in the pulled vacuum line. No smell of gas near the fuel rail or fuel lines between the rail and the tank.
Several key on - key off cycles are required to start the engine when it is hot.
Fuel pump check valve isolation test shows acceptable results, fuel pressure stays at 25-30 PSI for a couple of hours
Deadhead fuel pressure test shows very high value - 100 PSI or above.
No OBD codes.
Replacements:
Fuel pump - 2 years ago;
Fuel pressure regulator - recently, few times;
Fuel injectors - recently;
Fuel filter - 2 years ago.
Hypothesis:
Honestly, at this point of time could think of very few: Geometry of fuel pressure regulator socket is violated. In support to this theory there is a fact that I had to put extra washer on the regulator to prevent an obvious fuel leak through it. By other hand, I was not even able to find any mention of such a thing like fuel pressure regulator socket.
Or there is something in the system (fuel pump?) that immediately destroys the regulator. The fact is that one of the FPRs I changed had distorted lower part.
What else could I measure/test to diagnose the issue? Any ideas and brainstorming will be highly appreciated.
Thank you,
Karim
Problem: Hard start when hot, stalling while driving.
History of the problem: Long one. Available upon request.
Observations: The fuel pressure does not hold with key off, it immediately drops to 0. But it holds much better when engine is cold and the return line is pinched either right after fuel rail or near the tank. Fuel pressure is close to normal when engine is running. Fuel pressure regulator passes the test with pulling out the vacuum line - the fuel pressure increases by 10 PSI. No smell of gas in the pulled vacuum line. No smell of gas near the fuel rail or fuel lines between the rail and the tank.
Several key on - key off cycles are required to start the engine when it is hot.
Fuel pump check valve isolation test shows acceptable results, fuel pressure stays at 25-30 PSI for a couple of hours
Deadhead fuel pressure test shows very high value - 100 PSI or above.
No OBD codes.
Replacements:
Fuel pump - 2 years ago;
Fuel pressure regulator - recently, few times;
Fuel injectors - recently;
Fuel filter - 2 years ago.
Hypothesis:
Honestly, at this point of time could think of very few: Geometry of fuel pressure regulator socket is violated. In support to this theory there is a fact that I had to put extra washer on the regulator to prevent an obvious fuel leak through it. By other hand, I was not even able to find any mention of such a thing like fuel pressure regulator socket.
Or there is something in the system (fuel pump?) that immediately destroys the regulator. The fact is that one of the FPRs I changed had distorted lower part.
What else could I measure/test to diagnose the issue? Any ideas and brainstorming will be highly appreciated.
Thank you,
Karim