1995 GMC Truck Need help!

WIHUNTING2369

MEMBER
1995 GMC TRUCK
V8
4WD
AUTOMATIC
318,000 MILES

We have done almost everything we can and still haveing problems. The parts replaced is EGR, Idle position sensor, almost everything on the throttle body. It is tbi injected. The problem is mainly when it sits for about 8 hours or more, when starting it up it barely idles at 400 rpms. When running the fuel pressure is at 13 psi which the dealer said is right. The only other parts that haven't been replaced is the fuel regulator on the TBI and the fuel pump. After running a while it runs ok. Just don't get it. Both parts that haven't been replaced are GM original parts. This is my son's car and he said it takes about 30 + seconds when turning the key on (without starteing it) the pump makes two noises. I am thinking the fuel pump but don't want to have him have to replace the pump if we should replace the regualtor. Can you tell me what you think it may be? Thanks for any help you can give!

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

The only way to condemn the fuel pump and fuel pressure regulator is to check the actual fuel pressure with a fuel pressure gauge designed for your fuel system.

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Tuesday, May 5th, 2009 AT 12:27 AM

WIHUNTING2369

MEMBER
4 POSTS

We already checked the fuel pressure with a fuel pressure gage, that is how we know the pressure is 13psi. When he goes to start it just turning the key forward without starting it he said it takes a bit about 20-30 seconds for the pump to run and finally stop to build up the pressure. I am thinking that is too long to build up pressure? Do we need to check the pressure after it has sat for a while? He checked it after it had ran for a while let it cool for a bit then checked it with the pressure gage.