Does a GM oil pressure switch serve as a fuel cutoff ?

[gmc Jay]

Originally Posted by MT-2500

No way.
Oil pressure switch is not a fuel cut off switch.
It is a switch to keep engine running in case the fuel pump relay quits.

Does the relay click on and send 12 volts to fuel pump key on 2 second prime up or while cranking engine?

Best to start a new thread on your problem.
Give all info and someone will help you

ok thanks

[gmc Jay]

Originally Posted by gmc Jay

ok thanks

i took a power probe and put 12 volts to the Fp and the relay clicks but cant get power to the pump by the key switch

[gmc Jay]

Originally Posted by brcidd

Try whaaaaaping the fuel tank while someone else is trying to start it-- FP may be old and armature worn off center- whaaaaaping it can jarr it loose and it can start pumping--if so it needs replaced.

i put 2 new fuel pumps in it and replaced Fp relay

[MT-2500]

Originally Posted by gmc Jay

i took a power probe and put 12 volts to the Fp and the relay clicks but cant get power to the pump by the key switch

Instead of throwing parts at it and jumping stuff do some proper testing.
Also check fuel pump fuse right hand cowl under plastic fuel pump relay cover.

Get a test light on wire to fuel pump and check for 12 volts with key on 2 second prime up.
The first 2 seconds after key is turned on.
Or on engine cranking.
If you have 12 volts to fuel pump and pump does not run you have a bad pump.
Let us know what you find.

[Tech II]

I agree....you need to have 12 volts to the pump, PLUS, you need a good GROUND....

[j cAT]

Originally Posted by gmc Jay

i put 2 new fuel pumps in it and replaced Fp relay

just remember you need 12 volts and also a ground to get the pump to run. make sure the fuel pump is grounded.

with 12 volts at the fuel pump relay power contacts and none at the fuel pump you have a wiring problem.

[Phredster]

Ok I have 1994 gmc jimmy 4.3 vortec,.ran off road n down hill, truck wouldnt start sfter cuz fuel pump wouldnt engage, I traced connection and read YES oprs WILLNOT allow power to pump if in accident, I jumped the pins and voila pump sparked to life, I bought n installed new switch and pump now runs, now problem is spider Injectors not sending fuel and yes ive got 60 pounds at schrader valve. Vehicle will only run for short time on ether.

[JPs_1996_chevy]

Hey, I was reading this post and I was wondering if I could get some answers to a few questions. I had an accident last week and I broadsided a snow bank and my truck will no longer run. there is no physical damage to the truck other then it wont start. I have read several things about it being a fuel pump cutoff switch, an oil pressure cutoff switch, and several other things. I have checked the truck out and I found no cut wires or anything and I replaced the fuel pup within the last month. I don't have a filler neck on the truck currently because someone cut it off and swiped some fuel and I haven't replaced it yet. I did have a small amount of snow enter the fuel tank due to it so maybe the water and snow fried the fuel pump? im not sure. I have talked to shops and other forums and I cant seem to get a clear answer out of anyone as far as what it could be out of the few answers I did get.

[maxwedge]

Chestertown here, more info needed, got spark, will fire if you spray a small amt of starting fluid into the intake, also you hear the pump prime when the key is first turned on?

[Tech II]

They cut the top of the fill pipe off? Have a locking cap?

And you have been driving it like this? The CE light had to be on, because of this.....letting snow/moisture in, is not a good thing.....

Do as Max suggested....

[j cAT]

Originally Posted by JPs_1996_chevy

Hey, I was reading this post and I was wondering if I could get some answers to a few questions. I had an accident last week and I broadsided a snow bank and my truck will no longer run. there is no physical damage to the truck other then it wont start. I have read several things about it being a fuel pump cutoff switch, an oil pressure cutoff switch, and several other things. I have checked the truck out and I found no cut wires or anything and I replaced the fuel pup within the last month. I don't have a filler neck on the truck currently because someone cut it off and swiped some fuel and I haven't replaced it yet. I did have a small amount of snow enter the fuel tank due to it so maybe the water and snow fried the fuel pump? im not sure. I have talked to shops and other forums and I cant seem to get a clear answer out of anyone as far as what it could be out of the few answers I did get.

with the fuel filler cut off water will enter and then settle to bottom of tank. then the sock will freeze then no fuel.

no clear answer because you need to see if at the fuel pump connector you have power also check that ground at the fuel pump frame rail.

being below 20deg f frozen would be a good guess.

[ZakTPI]

The fuel pump safety shut off works off the camshaft position sensor, not the oil pressure switch.