Fuel pressure problems

[Sandy's LT1]

I hope someone can help me.I have had starting issues with my car for a few months now.It has a new FPR and the pump is only a year old.Replaced for the same problem I am having again.Here are my symptoms.Car is hard to start cold or hot, seems like it tries to stall driving down the road if rpms get below 1500 and Idle gets stuck at times.Like it will hang up at a 1000 rpms when I stop at a light or stop sign.I can hit the gas pedal and it comes right back down.Also my car has started up at around 2000 to 2500 rpms alot.Also smell fuel sometimes like its flooding.Okay here goes.My fuel pressure tests I have done.

1st test..Key turn to run,pump primes,pressure gauge goes to 20 psi and then drops 10psi and slowly bleeds down.

Test 2...Key turn to run,pump primes and makes a can crushing sound that came from the drivers side somewhere near front fender as noise is going on the fuel pressure needle is jumping with the noise.Goes to 40 psi,drops 10 psi and slowly bleeds down in about 15 mins to 0 psi.

Test 3...same as test 2

Test 4...Trying to start the car.Turn key to run,prime pump,makes same crushing noise,needle on gauge jumps with noise,hits 40 psi,I try to start and it turns over a few seconds before starting.Engine starts pressure drops to 30psi and holds.Turn car off,pressure drops 5 psi and then slowly bleeds back to 0 psi.

Test 5...Starting car with vacuum line off FPR.Prime pump,hits 40 psi,engine starts and holds at 40 psi.Put vacuum line back on and it drops back to 30 psi.Turn off car and bleed down begins.I hope someone has answers.

[Joe 1320]

Sounds like a possible leaking injector. The injectors should not pass any fuel unless the engine is turning. It may be time to pull the fuel rail and injectors, allow the fuel pump to pressurize the rail and check for fuel leakage from the injectors. The hard start may be coming from excess fuel, the fuel smell would tend to back this up and the same goes for the near stall until you open the throttle to allow additional air into the engine. Same goes for the fuel system not holding pressure when shut off.

Is there an SES light at any time? How many miles on the injectors?

[Sandy's LT1]

I have tested the injectors about 2 months ago and did not see any leaks.Hasn't been long since I cleaned them either.N0.
0o SES light has come on.Injectors have as far as I know 239,000 on them.139,000 I have put on them myself.So anything before those miles I don't know.

[Injuneer]

Try starting it by putting the accel pedal on the floor, and holding it there when you turn the key to "start". That puts the PCM in "clear flood" mode. If you have leaking injectors, starting it like that should help it start quicker. That would confirm the flooding due to injector leaks.

Sounds like your throttle blades are sticking a bit. Time to inspect the blades and make sure they are closing fully when you lift your foot. That would explain the high idle.

Another thing to look at, that would cause a rich start and a high idle would be the coolant temp sensor in the water pump housing. If that is telling the PCM the engine is colder than it really is, its going to cause a too rich start, and too high initial idle.

If the injectors are leaking or dirty, no SES light is going to come on. The only diagnostics for the injectors are checking the electrical circuits.

[Sandy's LT1]

Try starting it by putting the accel pedal on the floor, and holding it there when you turn the key to "start". That puts the PCM in "clear flood" mode. If you have leaking injectors, starting it like that should help it start quicker. That would confirm the flooding due to injector leaks.

Sounds like your throttle blades are sticking a bit. Time to inspect the blades and make sure they are closing fully when you lift your foot. That would explain the high idle.

Another thing to look at, that would cause a rich start and a high idle would be the coolant temp sensor in the water pump housing. If that is telling the PCM the engine is colder than it really is, its going to cause a too rich start, and too high initial idle.

If the injectors are leaking or dirty, no SES light is going to come on. The only diagnostics for the injectors are checking the electrical circuits.

I tried to start with accel pedal down.It would not start at all until I closed the throttle then it fired up.Left work and it turned over about 7 to ten times before starting.Ran fine afterwards.Picked up my son and started car with no problems this time.Runs great,but on occasions if I let off the throttle and go under 55 mph you can feel it surge,but it doesn't do it often. I think you are right about the butterfly blades.Gonna have to clean them again or see if they are worn. Fuel injectors are not leaking and have been cleaned and new O-Rings installed.I don't feel it's the coolant sensor at this time.