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Discussion Starter · #1 ·
I’m working on a 1994 GMC c1500 TBI 5.7 v8. I hadn’t started it in 5 days and it started with the first turn of the key today! But after letting it idle for 10 minutes, I shut it off and when I went to start it back up it would only crank over. When I opened the throttle all the way it would start to fire and then sputter out. This went on throughout the day. if I let it sit for 2+ hours, i would be able to get it running without much throttle. But after it had already been started it would only crank over (and fire if I floored it). The truck sat for the past 4 years until I fired it up a week ago. So far I’ve replaced the battery, plugs/wires and fuel filter. I’ve tested the fuel injectors with a 9v battery and with a multimeter, and they appear to be good. I think it is a problem with the fuel system because I have to give full throttle to get it to fire. But I could be wrong, I don’t have a ton of experience and am constantly learning. Does anyone have any ideas of what to could be going on? Could something be wrong with the injectors that wouldn’t be detected with the meter or 9v? I’m trying to get the truck running for my uncle so he has something to drive. Any help would be greatly appreciated!!
 

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Borrow a fuel pressure gauge from the parts store and see what it is. It needs to be between 10 and 13 PSI (GM says 9 - 13 but IMO 9 is too low). When was the last time you changed the fuel filter?
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Leaning towards fuel pump combined with bad gas.
 

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Discussion Starter · #6 ·
Borrow a fuel pressure gauge from the parts store and see what it is. It needs to be between 10 and 13 PSI (GM says 9 - 13 but IMO 9 is too low). When was the last time you changed the fuel filter?
I’ll check the pressure soon, thank you! I just changed the filter yesterday.
 

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Discussion Starter · #7 ·
Leaning towards fuel pump combined with bad gas.
Ive siphoned out the gas and put 5 gallons of fresh gas in it. It’s still probably mixed with a fair amount of bad gas at the bottom of the tank though. I’ve heard a lot of people say fuel pump, gonna check the fuel pressure soon and see how it looks. Thanks for responding
 
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