Fuel regulator question
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
Fuel regulator question
I have a L-89 out of a 89 Pontiac GTA in my 79 vette. I've read about disconnecting the regulator in some threads. The general answer is not to do it. Ever since I installed this motor in my car the engine dies when you unplug
the vacuum hose from the regulator. Is this normal or does something need to be looked into???
the vacuum hose from the regulator. Is this normal or does something need to be looked into???
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: Fuel regulator question (toyvet1)
The fuel pressure regulator should reduce pressure under high vacuum (idle and low throttle) and allow pressure to rise towards the pump's psi output as vacuum decreases (as throttle increases). By pulling vacuum line off the fuel pressure at idle should increase beyond what idle spec calls for. Unfortunately, I don't know how the engine you cited should respond to that situation, but I would think it would cause it to run rich which could in theory cause it to stall.
I probably haven't answered your question very well at all.
I probably haven't answered your question very well at all.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fuel regulator question (toyvet1)
Even if you don't plug the vacuum line it should not die out but anyway try putting your finger over the hose end.
It sounds like your ECM isn't in closed loop mode so can't correct for the sudden jump in fuel flow. If you have a stock Vette ECM with ALDL and such, use the method on my site to put it into diagnostic mode. This will tell you if it's going closed loop. If you have some other ECM, use a scanner to see what's up.
It sounds like your ECM isn't in closed loop mode so can't correct for the sudden jump in fuel flow. If you have a stock Vette ECM with ALDL and such, use the method on my site to put it into diagnostic mode. This will tell you if it's going closed loop. If you have some other ECM, use a scanner to see what's up.
Thread Starter
Burning Brakes
Joined: Jul 2000
Posts: 1,045
Likes: 3
Re: Fuel regulator question (65Z01)
When I ground out the a & terminals on the data aldl after the engine warms up it goes from open to closed loop. It has a Howell engineering wiring harness with a gm ecm unit (I would have to check to see what # it is).
