LT1 Fuel pump relay
LT1 Fuel pump relay I am about finished putting a '95 LT1 out of a Trans Am into an '86 Firebird and I cannot get the fuel pump relay to fire. I have the green/white hooked to the signal, power coming from a switched source, ground and output hooked up right but still won't fire. I can jump the relay from a 12v source and it will click the relay and fire it. I measured the voltage coming from the signal wire and it is around 9.7 volts. I contacted someone who measured the voltage from a car that I actually plugged my PCM in to program the vats and egr out of it and it would start the car and let it run and he measured 10.1 coming from the signal wire to the relay. This really has me stumped, the only thing I do not have is the C100 plug out of the PCM hooked up which has the power to the injectors and ignition, is it possible that this is causing the problem? I have tried 3 different relays, the original that came off of the 86, a universal 12v 4 pole relay, and a direct replacement for a 95 Trans Am.
Thanks for any help
Thanks for any help
Staging Lane
Joined: Mar 2005
Posts: 69
Likes: 0
From: LI, New York
Originally Posted by Klortho
Anyone at all? This is the last thing I need to do to get the car running, please any info would be great.
I really dont know they problem, grab a haynes manual! they help a lot!
Teching In
Joined: Jan 2003
Posts: 33
Likes: 0
From: Grand Rapids,Mi
hmmmm.......u have power going to the relay,but no power out? did u check to see if u have power coming out of the control side of the relay? Without any power there the switch side of the relay wont work.make sure u have power going into the switch side as well.If u have power at all places but no power coming out of the switch side of the realy,then i would say the contacts are bad on the switch side of the relay.
BTW.....I hopes this helps as I had to do this on a 2001 Lumina to get it to start,turns out the ground wire for the control side of the relay was bad,spliced in a new ground and she worked like a charm,it was a starter relay but im sure the same principles apply.
BTW.....I hopes this helps as I had to do this on a 2001 Lumina to get it to start,turns out the ground wire for the control side of the relay was bad,spliced in a new ground and she worked like a charm,it was a starter relay but im sure the same principles apply.
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The Pcm grounds the green/white to prime the fuel system prior to engine start. Once the engine starts cranking and the oil pressure switch closes at 4lbs of oil pressure it jumps 12v from the orange wire to the gray wire at the oil pressure sending unit then the pump stays running as long as the engine is running. The gray wire t's in with the wire coming from the fuel pump relay. They did however change it in the later years I believe and the fuel pump relay controlled all fuel pump functions and they did not use the oil pressure switch. If you need any info pm me and I can send you the diagrams off of alldata.
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Verdad Gallardo Well, got the motor going tonight, on the 95 model, the BAT to PCM wire is actually in the C100 connector, the underhood fusebox and plugs I got for the blue, white, and black connectors came out of a 94 and are totally different.
No BAT power to the PCM, no PCM signal to anything to make it work
It's the little things like this that makes a person feel small. But it's running using the underhood fusebox for the fans, ignition, injectors, and AC and not one piece of the old wiring that comes from the passenger side fender is in the car. Now just some cleaning up of the wiring, oil in the tranny and anti-freeze and it will be rockin' down the road.
Thanks for the replies on this and hope to talk to y'all about when I start modding
No BAT power to the PCM, no PCM signal to anything to make it work
It's the little things like this that makes a person feel small. But it's running using the underhood fusebox for the fans, ignition, injectors, and AC and not one piece of the old wiring that comes from the passenger side fender is in the car. Now just some cleaning up of the wiring, oil in the tranny and anti-freeze and it will be rockin' down the road.
Thanks for the replies on this and hope to talk to y'all about when I start modding
