1994 LT1 starting and low throttle issue
Thread Starter
Instructor
Joined: Jan 2011
Posts: 148
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From: Tulsa OK
1994 LT1 starting and low throttle issue
I am having a issue with my 94. It has had a starting issue for some time but later developed a issue while driving. when in the lower say 15% of throttle the engine looses a little power. It feels like its stumbling just a little. not missing but just not accelerating and even slowing just a little. If I push the pedal to say 25% or more the car pick's up. I put a pressure tester on and when I turn the key on it only goes up to about 25psi then bleeds down to zero in about 10 seconds.if I turn the key on and off and on quickly the pressure goes up to 40 or so but then bleeds to zero in about 10 seconds. I have replaced the pressure regulator and no change I pulled the fuel rail and primed the system and the injectors are not leaking. I am going to try a new fuel pump tomorrow. Does that sound like the issue to you guys?
Thanks for your input!!
Thanks for your input!!
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
I am having a issue with my 94. It has had a starting issue for some time but later developed a issue while driving. when in the lower say 15% of throttle the engine looses a little power. It feels like its stumbling just a little. not missing but just not accelerating and even slowing just a little. If I push the pedal to say 25% or more the car pick's up. I put a pressure tester on and when I turn the key on it only goes up to about 25psi then bleeds down to zero in about 10 seconds.if I turn the key on and off and on quickly the pressure goes up to 40 or so but then bleeds to zero in about 10 seconds. I have replaced the pressure regulator and no change I pulled the fuel rail and primed the system and the injectors are not leaking. I am going to try a new fuel pump tomorrow. Does that sound like the issue to you guys?
Thanks for your input!!
Thanks for your input!!
I would try one more thing first before removing the pump.
Remove the gas lid door assy. You will see two rubber lines coming off the fuel pump. Hook up your fuel pressure gauge and clamp off the return line. Now key up the ignition. Get the pressure up around 40+ and see if it bleeds off. I bet it bleeds off. Given you replaced the fuel pressure regulator with no change.
Now I would prime the pump and immediately clamp the feed hose off. If the pressure holds you confirmed you have a bad pump/hose issue inside the tank.
Thread Starter
Instructor
Joined: Jan 2011
Posts: 148
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From: Tulsa OK
thank you for the advice!! I hooked the pressure gauge up to the metal pipe at the top of the fuel pump. The same it only goes up to about 25psi then bleeds down to zero in about 10 seconds.if I turn the key on and off and on quickly the pressure goes up to 40 or so but then bleeds to zero in about 10 seconds. So I will be putting a fuel Pump in this weekend. That rubber fuel line that connects to the fuel pump metal pipe can it be replaced without dropping the tank?
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
thank you for the advice!! I hooked the pressure gauge up to the metal pipe at the top of the fuel pump. The same it only goes up to about 25psi then bleeds down to zero in about 10 seconds.if I turn the key on and off and on quickly the pressure goes up to 40 or so but then bleeds to zero in about 10 seconds. So I will be putting a fuel Pump in this weekend. That rubber fuel line that connects to the fuel pump metal pipe can it be replaced without dropping the tank?
Which rubber line? The two rubber ones that are at the end of the fuel lines? If that is the one you mean, NO. Even with the tank down, the rubber lines are crimped into the metal lines with a crimp fitting they are not really serviceable.
Now, inside the tank there is fuel hose that connects the pump to the sending unit and the metal pipe on top. That should be able to be replaced. Just need to pull the sending unit/pump assy. to get to that.
Thread Starter
Instructor
Joined: Jan 2011
Posts: 148
Likes: 1
From: Tulsa OK
Thank you for the info!! I was talking about on top of the tank. I replaced my pump and all is GREAT!!! starts right up and more power!
What I did was, I have a loose gauge I put a barbed fitting on it and the a small fuel line and hooked that up to the metal feed tube on top of the tank. That ruled out every thing down stream and told me the issue was in the tank.
What I did was, I have a loose gauge I put a barbed fitting on it and the a small fuel line and hooked that up to the metal feed tube on top of the tank. That ruled out every thing down stream and told me the issue was in the tank.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Thank you for the info!! I was talking about on top of the tank. I replaced my pump and all is GREAT!!! starts right up and more power!
What I did was, I have a loose gauge I put a barbed fitting on it and the a small fuel line and hooked that up to the metal feed tube on top of the tank. That ruled out every thing down stream and told me the issue was in the tank.
What I did was, I have a loose gauge I put a barbed fitting on it and the a small fuel line and hooked that up to the metal feed tube on top of the tank. That ruled out every thing down stream and told me the issue was in the tank.
Yeah, those rubber lines on the tank are non-serviable as you saw.
I don't like it either. I replaced EVERY fuel system o-ring seal last winter on my car for peace of mind. I found those non-serviceable. Bummer, but if I'm going to have a fuel leak in the back is better than the engine compartment.
Glad to hear the new pump fixed things for you.
