Strange 3800II starting issue.

[ron350]

This problem began about 6 months ago but has gotten worse lately but doesn’t set or store a code. The car is a 96 Regal 3800II and has a good strong battery and cranks over just fine.

 

Originally when the car was cold it would start and run rough like there was a vacuum leak until I reved it up and it smoothed out. So I found could start the car and turn the key off wait a few seconds and then restart the car and it would idle and run fine the rest of the day.

 

Now randomly when the car is warm and I go to start it will act like it has a large vacuum leak and stalls out after a few seconds of chugging. When this happens I have to hold the gas peddle to the floor to get it to start.

 

All I can think of causing this, without setting a code, is leaky injectors or low fuel pressure?

[Galaxie500XL]

Bad crank sensor? It wouldn't set a code.

[ron350]

Thanks Galixie500XL most threads I have read with a bad crank sensor the car will die while driving and then restart like nothing happened or never restart.

I will have to go back and reread some of those old threads.

1996 was the first real year for OBD2 systems and have read they don’t set codes as well as 1997 and newer cars?

[l67ss]

Have you done a fuel pressure test? Could be a dying fp

[RobertISaar]

kinda sounds like what has been described to me as the L36 grenade: leaking fuel pressure regulator dumps fuel into the intake, backfires and then the plenum is done.

[ron350]

Today for the first time I could not hear the fuel pump prime with the ignition switch on. My hearing is getting bad but I still should be able to hear it prime.

 

When I depressed the fuel Schrader valve the gas did not spray out like I think it should. Next step is a fuel pressure test.

 

Checked the fuel pressure regulator and it still holds a vacuum.

Checked the idle air control valve and it only had a little soot so cleaned and lubed that. Once again thanks for any and all help.

Edited December 27, 2014 by ron350

[l67ss]

Today for the first time I could not hear the fuel pump prime with the ignition switch on. My hearing is getting bad but I still should be able to hear it prime.

 

When I depressed the fuel Schrader valve the gas did not spray out like I think it should. Next step is a fuel pressure test.

 

Checked the fuel pressure regulator and it still holds a vacuum.

Checked the idle air control valve and it only had a little soot so cleaned and lubed that. Once again thanks for any and all help.

 

Make sure ur getting power to the fuel pump. Would b a bitch to drop $400 on a new pump just to find out it wasnt the issue. There is a resister on l67 ws by the battery....try bypassing it and see if the pump kicks on. If it does id just leave it bypassed.

[l67ss]

Make sure ur getting power to the fuel pump. Would b a bitch to drop $400 on a new pump just to find out it wasnt the issue. There is a resister on l67 ws by the battery....try bypassing it and see if the pump kicks on. If it does id just leave it bypassed.

 

Sorry ignore the resister part of this post...a 96 regal wouldnt have one lol. But like I sed check for power at the pump b4 replacing parts

[ron350]

I finally checked the fuel pressure and it is low.

 

It is 35 psi at key on 2 second fuel pump priming, should read 48 to 55 psi. Back in 2006 when I checked the pressure it was 49 at key on prime.

I guess this would explain the strange starting problem?

 

It idles at 42 psi which is within the allowed 38 to 50 psi idle range.

 

I guess the fuel pump is just worn out after 19 years.