Fuel shortage

Tiny
CARDAN
  • MEMBER
  • 1993 CHEVROLET S-10
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
My truck will run fine when it wants to, then it just shuts off like it is starving for fuel. Start it and play with the accelerator for a while and it will do good for a few minutes days, or miles. I have already replaced the fuel filter and pump and still, at an inopportune moment it shuts off. Would the fuel pressure sensor act like this or if it were bad would the truck just not run? There are no codes entered in the OBC other than weak "spark knock sensor" and that was also an on/off thing not in conjunction with the engine shutting off.
Tuesday, February 21st, 2017 AT 5:19 AM

10 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
How long since over-all tune-up? If you think a fuel issue, did you check fuel pressure? With TBI the pressure is usually around 9-13 psi. Can you see the fuel injector/s spray pattern?
Do you think the knock sensor may be your problem?
With intermittent issues, you need to test when problem is ongoing. I know it is a pain. An intermittent rpm signal can drive you crazy. I need something to point us in the right direction?
At the top of page is a repair guides link, a lot of good information.
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Tuesday, February 21st, 2017 AT 8:52 AM
Tiny
CARDAN
  • MEMBER
  • 6 POSTS
I put in new plugs and wires at the same time I changed the fuel filter (about two hundred miles ago). I had a friend test the pressure and he said it was at 11.5. That was with the old fuel pump, but he said he did not think that would matter because it was running good just before he tested it. He has have told me and I have read that the original fuel pumps in the S-10's were not the best. So I connected a wire from the tank to the frame to ensure a good ground, and when that did not work I put in the new fuel pump. It has the throttle body Injection and I am thinking of replacing the relay next, but I do not like spending money.
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Tuesday, February 21st, 2017 AT 9:25 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Talking about the fuel issue, there is an oil pressure switch in the fuel pump circuit. It is just a redundant power supply to the pump. As long as that switch is functional and has voltage, the pump will run, even without the fuel pump relay.
Intermittent issues are difficult.
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Tuesday, February 21st, 2017 AT 9:42 AM
Tiny
CARDAN
  • MEMBER
  • 6 POSTS
Are there any other sensors that could be faulty? And if so, can they be tested?
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Tuesday, February 21st, 2017 AT 10:15 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Without something to point us in the right direction, it is like hunting a needle in a hay stack, in my opinion? Can you communicate with computer at all? Can you force it to set a code, to see if it works? When it stalls does the dash lights go out?
With intermittent issues, have to test when problem is ongoing.
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Tuesday, February 21st, 2017 AT 10:26 AM
Tiny
CARDAN
  • MEMBER
  • 6 POSTS
I have a code reader but I don't know what you mean by forcing it to set a code. As far as the lights, everything stays on.(Except the engine)
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Tuesday, February 21st, 2017 AT 10:58 AM
Tiny
JDL
  • MECHANIC
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You could unplug the tps or some other sensor, then turn on the key or start it. Then see if your code reader will show a code. Does the code reader just make the check engine light flash and then you count the flashes to get the codes?
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Tuesday, February 21st, 2017 AT 11:59 AM
Tiny
CARDAN
  • MEMBER
  • 6 POSTS
My code reader only makes the engine light flash, but I will try unplugging a sensor and get back with you. Thanks
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Tuesday, February 21st, 2017 AT 1:21 PM
Tiny
CARDAN
  • MEMBER
  • 6 POSTS
I unplugged the sensor and the check engine light came on, but went off when the sensor was plugged back in. Could this be as simple as blockage in the fuel line? I had that happen to me once on a Toyota back in the 80s.
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Tuesday, February 21st, 2017 AT 4:44 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Sure, it could be almost anything.
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Wednesday, February 22nd, 2017 AT 7:45 AM

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