Need HELP! Only 7 volts going to fuel pump.

[fearsno1]

Had the car (87 GN) running just fine 1 week ago, went to crank up yesterday and no fuel pressure, no pump running. Started running some checks, I do have a hot wire kit, and from the stock harness going into the Hotwire harness, I am only getting 7 volts and that isn't enough to trigger the Hotwire kit relay. I did jump 12 volts to the Hotwire relay and pump runs and car runs fine. 7 volts switches on/off with key on/off ignition, so that tells me that the fuse and relays are actually working but I can't seem to figure out why I'm not getting enough voltage , I've cleaned the fuse and relay contacts, checked grounds. I'm baffled, as I can diagnose a no voltage issue but lost on a low voltage one.

Any help is appreciated!
Thanks
Brandon

 

[TurboDave]

Start tracing your hotwire voltage from its source to the point of loss

 

[fearsno1]

I don't know where the wire at the tank (that has 7 volts) goes to, do you know where that traces back to?

 

[TURBOELKY]

I believe it's in the flat plug on the side of the fuse block. It runs along the drivers side door all the way back. Open your trunk and you'll see a bulk head connector in the wheel well
Area. That's the best way I can explain it.

 

[pacecarta]

are you certain you are checking the pump wire and not the sending unit , FYI the pink middle wire is not the pump
tan is to pump, pink to sender, black is ground

 

[dynoman]

Did you apply 12v to the fuel pump connector behind the alternator? If the pump comes on your problem is probaby over in the factory relay and or connector. 7v is a high resistance connection somewhere from underhood relay to hot wire relay .

 

[fearsno1]

what is this fuel pump connector behind the alternator that you speak of? i have no clue on that one

 

[fearsno1]

are you certain you are checking the pump wire and not the sending unit , FYI the pink middle wire is not the pump
tan is to pump, pink to sender, black is ground

i will double check my findings

 

[dynoman]

what is this fuel pump connector behind the alternator that you speak of? i have no clue on that one

Black connector with a grey wire , put 12v to that connector and the fuel pump should turn on . You might have to root around in the harness but it should be right in that general area . If you find a green connector that is for a tach , don't put 12v on that one .

 

[fearsno1]

damn i was wondering what that was for! thanks I'll try that, now what if the fuel pump doesn't run when 12 volts is applied? also what is the tach connector for?

 

[pacecarta]

damn i was wondering what that was for! thanks I'll try that, now what if the fuel pump doesn't run when 12 volts is applied? also what is the tach connector for?

its pretty much self explained ..its for attaching a tach , useful for diagnosis when using a real tachometer

 

[earlbrown]

Does the pump run (and the car start) if you crank long enough for the 'oil' light to go out?

 

[fearsno1]

found a loose wire on the harness that goes into the ECM, I moved those wires around and the pump kicked on. Thanks for the help guys.