87 Chevy Won't Start

TroyisBig · December 14, 2009

working on an 87 chevy shortbed 4x4, throttle body, 350. I do not have any fuel spraying. I can not hear the fuel pump initiate when ignition is turned on.

Fuel pumps where supposedly replaced a few years ago. Truck has been sitting for several years, but seller said he started it 6 months ago and let it run 30-45 minutes.

It will start and run momentarily on fuel poured in the throttle body.

Where is the fuse that controls the pumps? I can not find anything related to them on the fuse block.

I can not get to the wiring on the pumps to check voltage there - unless i am missing something.

The tank selector switch on the dash when changed does not change the gauge indicator.

Can I check fuel pressure by cracking a line somewhere?

Nytemare · December 14, 2009

working on an 87 chevy shortbed 4x4, throttle body, 350. I do not have any fuel spraying. I can not hear the fuel pump initiate when ignition is turned on.

Fuel pumps where supposedly replaced a few years ago. Truck has been sitting for several years, but seller said he started it 6 months ago and let it run 30-45 minutes.

It will start and run momentarily on fuel poured in the throttle body.

Where is the fuse that controls the pumps? I can not find anything related to them on the fuse block.

I can not get to the wiring on the pumps to check voltage there - unless i am missing something.

The tank selector switch on the dash when changed does not change the gauge indicator.

Can I check fuel pressure by cracking a line somewhere?

If you cant hear the pump running...you don't have fuel pressure anywhere... there should be a little red wire running down the with the big bundle of wires (main harness) at the rear of the driver side fender. It should be about 6" long and have nothing hooked to it. It will have a black plastic end on it with a contact inside. This is the emergency fuel pump bypass. You put battery voltage to this wire and it starts the pump. If it doesn't than the pump is toast. If it does...than you have a bad fuel pump relay, or fuse. I cannot recall where either is right now for sure...but something tells me they're under the dash on the passenger side.

alwcurlz · December 17, 2009

Sounds like Aiden knows that truck well! I have other thoughts and ideas to throw your way. You couldn't have both pumps bad at the same time after the truck not being run for 6 months. That sounds like an environmental (cold/moisture) change to me.

I was thinking that if there are two tanks, two fuel pumps and you can't hear either one operate and the fuel gauge does not function, it sounds like the fuel tank selector control switch is faulty, or a bad/disconnected/cut/shorted wire not sending necessary current/completing the circuit. I would find the switch and manually activate it. I would also suspect a bad relay; locate the relay and check it. You could also bypass the relay temporarily with a jumper wire.

After all this, I would also consider changing the fuel filter if it's been sitting for a while. There's possibly varnish or even water froze in the system in places like the fuel pump impeller? If it's been 6 months ago, then you had summer fuel in the tank which has more water in it.

BTW, where geographically are you located?

Hope this info helps!

Nytemare · December 17, 2009

Sounds like Aiden knows that truck well! I have other thoughts and ideas to throw your way. You couldn't have both pumps bad at the same time after the truck not being run for 6 months. That sounds like an environmental (cold/moisture) change to me.

I was thinking that if there are two tanks, two fuel pumps and you can't hear either one operate and the fuel gauge does not function, it sounds like the fuel tank selector control switch is faulty, or a bad/disconnected/cut/shorted wire not sending necessary current/completing the circuit. I would find the switch and manually activate it. I would also suspect a bad relay; locate the relay and check it. You could also bypass the relay temporarily with a jumper wire.

After all this, I would also consider changing the fuel filter if it's been sitting for a while. There's possibly varnish or even water froze in the system in places like the fuel pump impeller? If it's been 6 months ago, then you had summer fuel in the tank which has more water in it.

BTW, where geographically are you located?

Hope this info helps!

True that with the varnish, water...etc.

Also the switch makes a lot of sense. That's the reason I told him to find the FP bypass...that puts 12V directly to the pump.

Also...its been sitting for a long while...and mice/rats love copper wire...for some reason.