Engine will not stay running

Tiny
JOHNSONAPE
  • MEMBER
  • 1998 CHEVROLET S-10
  • 2.2L
  • 4 CYL
  • 2WD
  • MANUAL
  • 186,000 MILES
I had a problem with my truck shutting off about a month ago. I replaced the fuel filter which was plugged up fairly bad and the IAC. It ran good for another month. I kept smelling gas after driving and then it started acting the same again. I thought maybe the fuel pump took went bad so ordered one and a new gas filter. To my surprise when I raised the bed the fuel pump was standing up out of the tank. The snap ring had rusted so I replaced it. The pump had been replaced since it had the upgraded connector. I put on the new connector anyhow since some of the connections were iffy. Now I still have the same problem, it will start and maybe idle for 30 or 40 seconds then shut off or if I rev it up it might run for a minute and shut off. Any ideas?
Friday, June 5th, 2020 AT 7:10 PM

7 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I suspect this is fuel related. The fact that when you raise the RPM points to a fuel issue. So let's just start with checking the pressure and go from there. The pump may be new but if the pressure is not sufficient then we could have a faulty pump or other issue causing low pressure. The only way to know this is the issue is to test it.

Here is a guide that will help with this. Let me know what you find with this and we can go from there. Thanks

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Friday, June 5th, 2020 AT 7:22 PM
Tiny
JOHNSONAPE
  • MEMBER
  • 22 POSTS
Okay, so I rented the pressure gauge kit but to my dismay now the pump won't actuate when cycling the key. I wired the pump direct and it runs as does the old one I removed so I think I have an electrical problem. I checked the fuses and they are good. I swapped out some relays to no avail. I only have juice to one prong on the relay (there are 4) I'm not sure if I should have juice to more than the one. Something is keeping the fuel pump from running. My security light does not blink. It comes on but goes out so I don't think the anti-theft is the problem. I checked the ground at the rear of the truck and it is not broken. I even ran a ground wire from the battery to the pump but no success. Is there an inertia switch on this truck? Any help appreciated. Also my gas gauge doesn't work with the new pump which I suspect is the sensor or fingers on it are not making good contact.
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Saturday, June 6th, 2020 AT 1:46 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I attached the wiring diagram. Let me know what pin you have power on. You should have power all the time coming from the fuse. Then when you turn the key on you should have power coming from the Dark Green and White wire on B7 which is the control wire from the PCM (terminal 85 on the relay). Basically this supplies power and the relay gets closed. The F7 (terminal 86) wire is the ground wire for the relay control so it should not have voltage on it.

When you have power on the B7 wire and it closes the relay you then have voltage on the A7 and F1 wire (terminal 87). This is what powers the fuel pump and injectors.

What I would suggest is jumping power from 85 to 87 terminal and see if the pump turns on with the key on.

Let me know what happens with this and we can go from there. Thanks

FYI, when you are looking at the relay and you remove it, the terminals are in the position shown on the diagram. So when the relay is out, the to left is terminal 30 and the top right is 85. So jump 85 to 30 if you have power on 85. Let me know. Thanks
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Sunday, June 7th, 2020 AT 4:38 PM
Tiny
JOHNSONAPE
  • MEMBER
  • 22 POSTS
Okay, well I'm not sure what I did but upon removing the PCM to get it tested I decided to try and start the truck first. I'm not sure if swapping relays did it or maybe I have a iffy connection at the module but it started up and runs like a champ. I test drove it for about 25 miles through town with no problems. I'll see what it does tomorrow as I plan to drive it to work and let you know. Thanks for all of your help. I did have power to 85 only.
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Sunday, June 7th, 2020 AT 5:15 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. That is great news. If you had power at 85 only then the connection from the PCM was okay as this is what supplies that power.

If you swapped the relay I suspect that was the issue. However I am wondering if it was 30 that you had power on because this should have power all the time and removing the relay is not going to change that. So removing the PCM connector would restore power to 85 if it was loose.

Either way you got it running and that’s what matters. Thanks for the update.
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Monday, June 8th, 2020 AT 3:37 AM
Tiny
JOHNSONAPE
  • MEMBER
  • 22 POSTS
Thanks for your information Kenny. I didn't actually remove the connector to the PCM, I just unbolted it and brought it out from underneath the fender. I'm pretty sure it was 85 that I had power on but I was pretty frustrated at that point. Now I am wondering if it is a bad connection at the PCM and I merely moved it enough to make a good connection. Anyhow the truck ran fine today both to and from work.( About 74 miles mostly freeway) I will keep you updated. Thanks again.
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Monday, June 8th, 2020 AT 6:11 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Yeah. I think you are exactly correct. I would put my money on a connection issue that you fixed when you reseated it.

Thanks for that info. I am sure that will help others that have this issue when they read what you did.

Come back next time you have an issue. Thanks again for using 2CarPros.
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Tuesday, June 9th, 2020 AT 6:08 PM

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