Cranks but no start

Tiny
JUNIORDRITSAS
  • MEMBER
  • 1993 CHEVROLET 1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 126,000 MILES
Hello, one morning went out, truck would just crank, I changed the fuel pump relay, truck started after stepping on the pedal, then it was good all week, after the week it did the same thing all over, just would crank. Any help would be appreciated. Oh yeah, when the key is on, the oil pressure gauge moves around a little.
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Thursday, September 16th, 2021 AT 5:55 PM

18 Replies

Tiny
SQM
  • EXPERT
Hello,

Can you hear the fuel pump with the key to the on position?

If you can hear the pump then you need to see if you have fuel pressure. In case a faulty regulator is causing the issue.
You should have 9-13 PSI of fuel pressure with the key on and engine off.

https://youtu.be/aITQclp7zIE

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know what you got.

Thank you.
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Thursday, September 16th, 2021 AT 9:33 PM
Tiny
JUNIORDRITSAS
  • MEMBER
Yes, I can hear the fuel pump from the tank with the key on.
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Friday, September 17th, 2021 AT 8:00 AM
Tiny
SQM
  • EXPERT
So if the pump is coming on then you need to check the fuel pressure. If the pressure is low then you could have a bad regulator or could be a restriction in the line.

Have you already checked to see if you have spark?
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Friday, September 17th, 2021 AT 9:35 AM
Tiny
JUNIORDRITSAS
  • MEMBER
Checked it today, I do have spark on number 1 plug.
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Sunday, September 19th, 2021 AT 7:22 PM
Tiny
SQM
  • EXPERT
Make sure you are getting fuel. It should be 9-13 PSI with the key on and engine off.
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Sunday, September 19th, 2021 AT 7:44 PM
Tiny
JUNIORDRITSAS
  • MEMBER
I was told that the ignition control module controls the injectors, is that true?
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Sunday, September 19th, 2021 AT 9:16 PM
Tiny
JUNIORDRITSAS
  • MEMBER
It doesn't seem to be getting fuel, have buzzing from the tank from the fuel pump though.
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Sunday, September 19th, 2021 AT 9:18 PM
Tiny
SQM
  • EXPERT
The ignition control modules provides spark to the plugs, it does not control the fuel pump or fuel flow.

So you said you can hear the pump with the key to the on position?
If the pump is coming on but you do not have proper pressure, it could be due to a clog in the line, could be a fuel filter that is jammed or a bad regulator.
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Sunday, September 19th, 2021 AT 9:37 PM
Tiny
JUNIORDRITSAS
  • MEMBER
What exactly does the fuel pump relay do?
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Monday, September 20th, 2021 AT 10:54 AM
Tiny
SQM
  • EXPERT
The fuel pump relay provides power to the pump. If the relay is bad then the pump will not get any power and will not turn on. So if you can hear the pump come on the relay should be good.
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Monday, September 20th, 2021 AT 11:08 AM
Tiny
JUNIORDRITSAS
  • MEMBER
What's weird is what I started out with, wouldn't start, then I changed the fuel pump relay then it started, but only lasted a week.
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Monday, September 20th, 2021 AT 12:35 PM
Tiny
SQM
  • EXPERT
Interesting, so on the last time did you hear the fuel pump come on?

Have you got a chance to check the relay this time?
Here is a way to test the relay just in case:

https://www.2carpros.com/articles/how-to-check-wiring
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Monday, September 20th, 2021 AT 12:48 PM
Tiny
JUNIORDRITSAS
  • MEMBER
Yeah, I couldn't find where testing the relay was at on the page.
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Monday, September 20th, 2021 AT 1:53 PM
Tiny
SQM
  • EXPERT
Sorry about that. I have sent you the wrong link. Try this please:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Thanks.
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Monday, September 20th, 2021 AT 2:58 PM
Tiny
JUNIORDRITSAS
  • MEMBER
Yeah, I just went out and squirted some gas in the carburetor, I get nothing.
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Monday, September 20th, 2021 AT 4:01 PM
Tiny
SQM
  • EXPERT
If spraying fuel does not start the engine, then you might not have spark. As you know the two of the basics for engine start is spark and fuel.

Do you know if you are getting spark to the plugs. You can just pull one of the plugs and crank to see if it sparks.
And also if your pump is coming then it should be getting some fuel.

Lets take a step back, let me know what you have tried so far, this way we can figure out the next best step.
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Monday, September 20th, 2021 AT 9:48 PM
Tiny
JUNIORDRITSAS
  • MEMBER
Well, I went out and bought a cap and rotor, ignition control module, going to put them in today.
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Friday, September 24th, 2021 AT 11:21 AM
Tiny
SQM
  • EXPERT
Let me know how it turns out.
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Friday, September 24th, 2021 AT 12:27 PM

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