DuckyD

Hi, new member trying to fix my dad's '98 Chevy S-10. It's the 4.3L Vortec 2WD model. So here's the symptons.
Once or twice I drove the truck on a short trip and when I went to start it again, it wouldn't start. We traced it back to the fuel pump because we couldn't hear it prime when the ignition was turned on. It was intermittent and inconsistent.
Finally, the truck wouldn't start at all. Once again, the fuel pump would not prime. We towed the truck home and took off the bed to expose the fuel tank. Checked the voltage at the plug and the 1-3 connection reads 5 volts with the ignition on (fuel level sensor). We tested 2-4 and got 0 volts (fuel pump power supply). I am using the Hayne's manual by the way, this is the plug that I am talking about--> http://www.goodlinesracing.com/DumpFolder/pump.jpg .
So, it seems that the fuel pump is not getting any power.
We checked all fuses in the truck (by the driver's side door) as well as all the fuses and relay's in the engine bay and they are all good as well (replaced the relays with known good ones). This did not remedy the problem either.
Finally, I hardwire the fuel pump in the truck to a car battery, and sure enough it ran.

So, back to square one... It's a wiring issue.

The Hayne's manual states "If oil pressure drops below the specified pressure level, the oil pressure switch will act as a fuel pressure cut-off device" Be sure to check the oil pressure switch and circuit in the event of a difficult problem diagnosing the fuel pump circuit." But I cannot find anywhere in the manual that describes this oil pressure switch (location/description/diagnostic). Also, reading this--> https://chevroletforum.com/forum/sho...0&postcount=23 makes me wonder if it could be an ignition switch. How do I get to it or test it?

Please, help? I've tried searching but have not found a clear answer.

r2redmules

remember you have too check the terminal within two seconds of turning key to on position, because the system only runs for two secs at a time till the truck starts so it dont keep the fuel pump working. the oil seding unit has to show psi to get it to close for the pump to turn on and keep going, and on & on& on

grez0214

I have a similar problem, i have check all of that and have power back to the fuel pump plugs. When it was running yesterday, i heard the fuel pump running for about 60 seconds then i turned the car off. I don't think that is right either. it doesn't start now. I checked the relay, the ground by the fuel tank, no luck. Any suggestions.