1988 GMC Sierra Fuel Pump?

Tiny
RIVERRAT45750
  • MEMBER
  • 1988 GMC SIERRA
Engine Mechanical problem
1988 GMC Sierra V8 Four Wheel Drive Automatic 118k miles

Electrical systems engage fine, starter engages and performs properly, yet engine does not start. When it is above 50 degrees or so, it can be "coaxed" into starting, but it is still reluctant. Once it has been started, it will start right up again, with or without any driving. But once it sits overnight, it becomes reluctant to start again. Is my fuel pump allowing the gas to drain, or is it something else?
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Saturday, February 27th, 2010 AT 11:09 AM

6 Replies

Tiny
JDL
  • EXPERT
Hi, how long since a tune-up? If you suspect a fuel issue, I'd use a fuel pressure gage, first. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. Are there any trouble codes?
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Saturday, February 27th, 2010 AT 11:31 AM
Tiny
RIVERRAT45750
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K. My brother (trained mechanic) tuned it up before he passed last summer. I got it after that. No codes present when hooked up to a scanner. Will try the fuel pressure gauge. Thanks for the help!
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Saturday, February 27th, 2010 AT 11:37 AM
Tiny
RIVERRAT45750
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Hooked truck to a fuel pressure guage, pressure reads about 28# with the key in, and about 55# at idle. I think this is within the normal range, but I am not sure. If so, where would I search for the problem? Thanks for any help you can provide.
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Saturday, February 27th, 2010 AT 2:56 PM
Tiny
JDL
  • EXPERT
The info I looked at was, gasoline-- TBI-- fuel pressure around 10 psi. Do you have two injectors in the throttle-body, you should be able to see them spray gas?
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Saturday, February 27th, 2010 AT 3:39 PM
Tiny
JASON0821
  • MEMBER
I have a simiar problem. I got a 90 1500 305 and we changed the injectors and still nothing coming out. We tested if any volts and nothing. Could it be the ignition module? The fuel pump works the filter is fine gas comes all the way up but not spitting out the injectors. Could it be something else? I need to know because alot of us are working and we are now on one car so I need to fix the truck. Pease help me out
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Wednesday, March 10th, 2010 AT 8:16 PM
Tiny
JDL
  • EXPERT
Are you talking about 90 GMC? Injector A fuse in your fuse box is voltage for the injector, goes hot when you turn on the key.


http://www.2carpros.com/forum/automotive_pictures/170934_injector_A_fuse_1.jpg

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Thursday, March 11th, 2010 AT 9:42 AM

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