Loss of power with full tank of gas?

RICHIEBATSON

MEMBER
1999 GMC YUKON
V8
4WD
AUTOMATIC
88,000 MILES

Run good until you fill the tank up then it seems to have loss of power under a load like up hills and you can hardly give it gas without it bogging out. When gas gets below half tank it seems to run better but still stalls a little when stomping on the peddle. No check engine light and it just passed emissions. Could it be the fuel pump or filter. It's just strange it gets worse with fill up PLEASE HELP ME!!

4 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

That is odd, what you need to do is get a manual fuel pressure gauge on it to see what its doing when the tank is full pressure-wise vs. Fuel pressure before the fill up, this will at least give some direction to go in

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Thursday, May 14th, 2009 AT 7:56 AM

LARRY MEACHUM

MEMBER
2 POSTS
1998 GMC YUKON
210,000 MILES

Just had the heads redone. Now the SUV lose power wont go over 3000 to 4000 rpm. And needs to be primed with staring fluid to start. Car was running good before the heads where done. Having problems with the mechanic he said it may be timing but does not have a timing light (this is a reg. Repair shop) the SUV is not missing. No Eng. Lights. Though it was bad gas, put gas treatment an more gas. Has ran it long enough to run any bad gas out. Don't think that was ever the problem
GMC Yukon SLE 1998
5.7 Eng.

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Saturday, November 16th, 2019 AT 2:30 PM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Check fuel pump pressure. As far as timing, that is controlled by the computer.

To me it sounds like you have a weak pump.

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Saturday, November 16th, 2019 AT 2:30 PM (Merged)

LARRY MEACHUM

MEMBER
2 POSTS

We did that and it has good pressure. I forgot to add that to the question. As for the timing that was my thoughts too but the mach. Though the distributors was maybe installed off. I don't know.

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Saturday, November 16th, 2019 AT 2:30 PM (Merged)