97silver

Hi Everyone,
I bought a 92 silverado k1500 with a throttle body.
I put a new fuel pump in it and the pump does not run with the key in the on position, engine not running. It fires right off with 15lbs. psi. and runs good when I start it.
Does it hurt the pump or anything to just drive the pickup that way? Will it leave me stranded or anything because of it? I'm going to be switching it over to carburetor a little later on and I don't think I need the pre prime for carburetor, do I?

I have 8.7 volts at the center wire at the pump, which I think is for the prime. I'm going to try to find the problem and fix that to, but if it won't hurt the pump to run it like it is then I can go ahead and us the pickup while I'm trying to find the problem. If you have any ideas on what could be wrong I would appreciate the help.

Thanks a lot for the help. You are all great.

Irish_alley

The pump should only get power for 3-5 seconds (really depends on the ecm program) to prime the lines. Once started the ops sees 3+ psi it will complete the fuel pump circuit and the pump will run. Almost sounds like the relay has failed, normally you can tell by extended crank time for the engine, normally around 5 seconds. If you apply B+ to the 3" red wire on the relay (found on the firewall) do you hear the pump run?

97silver

Thanks Irish,
I think I got it figured out. I think it is my ignition. I would wiggle the key around and the buzzer would skip. So I wiggle it around some more and now I have 15psi. when key is turned on for a few seconds and when the relay clicks the pressure goes back to zero. With the engine running it holds at 14 - 15psi.

Can you tell me if a 92 TBI is supposed to hold pressure, after the relay clicks, for awhile?

Thanks a lot for the help. I very much appreciate it.

Irish_alley

no its not. theres no check valve or anything in the system.

97silver

Thank you again Irish,
I ordered a new ignition switch and key cylinder, so that part should fix the pump problem.
And, I'm glad I don't have another problem to figure out with holding pressure.
That's why all of you on here are so important to us that don't know.

Thank you,
Michael

Irish_alley

prob only need to replace the switch

97silver

The key seems a little loose in there also so I figured beings I got to take the steering column apart I might as well change both.
I agree that the switch itself is probably the culprit for my pump issue.

Thanks again. Have a good weekend.