Fuel pump not working properly

1993 CHEVROLET SILVERADO
100,000 MILES • 5.7L • V8 • 2WD
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LUDWICK
  • MEMBER
  • 2 POSTS
Truck runs fine during the warm-up. And then all of a sudden it shuts off the fuel pump. doesn't seem as it is working. cycle the key a few times sometimes it'll start but most of the time you'll have to pour fuel down the throat and it starts and will run again for 5 minutes, and then all the sudden boom it's stops. what would cause the fuel pump to just stop like that? I heard that the oil pressure switch controls the fuel pump if there's a low oil pressure but oil level is good oil pressure is is good on the gauge so I don't know if that could be that. any help would be appreciated. thank you, Patrick
Mar 14, 2020 at 8:28 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Good afternoon.

The pump is overheating and locking up when it gets hot.

You need to replace the pump.

To be sure, verify power to the fuel pump when it will not start.

Roy
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Mar 14, 2020 at 9:10 AM
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LUDWICK
  • MEMBER
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Roy thank you for responding. checked the power going to the fuel pump when it is running and as the idle comes down the injector shuts off but the power to the pump is still on for a brief second after the shutdown. I don't know if the truck has a crankshaft sensor, but maybe. it seems like it's not picking up rotation at the lower RPM. I think the ECM can shut down the fuel pump if it doesn't get a rotation signal. but I'm not sure on the Chevrolet, but I also forgot what I had for breakfast this morning.
Mar 14, 2020 at 10:52 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
If the engine stalls, the pump will shut off. The RPM signal comes from the distributor. When it stops turning, the ECM stops voltage to the pump.

No, there is no crank sensor for this early of an engine.

Roy
Mar 14, 2020 at 10:55 AM
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