Losing 12V power at the fuel pump

[alik]

Funny thing is, at the connector everything measures out fine. Two grounds, a 12V (11.9) and 6V (for the gauge). The fuel pump, when plugged into the battery jumper, runs just fine, yet when plugged into the connector, everything immediately drops down to almost non-existing.
My mechanic thinks there's a draw somewhere. I'm pretty much stumped.

Btw, my waterneck bundle is completely frayed and thus not plugged in, and my headlights decided that after two years of sitting they will no longer turn on. Don't even know if there's power going to the lights. Could that have something to do with the draw disappearing at the fuel pump?

Thanks!

 

[GSTwithPSI]

Did you try and apply 12v to the fuel pump test connector on the firewall? Plug the fuel pump in, and try that. It is a little spade connector near the timing grounding plug, close to the data plate on the firewall.

 

[belize1334]

If the wiring gets degraded by age then it can't support the current so the impedance of the wire jumps up as soon as the pump turns on and then the voltage at the pump takes a bomb. The common fix is to bypass the original wire with a new, higher gauge, fused wire that you run off of a relay in the engine compartment. Then you use the original wire to signal the relay. Look on www.vfaq.com for a fuel-pump rewire tutorial. It's the same as for a 1G except for the location of the fuel pump access panel, which you've already found.

 

[alik]

Thank you.
Looks like I've got some reading to do

 

[belize1334]

As was mentioned, before you go doing the rewire, check the voltage of the fuel circuit in the engine bay while the pump is online. You'll have to use the fuel pump tester circuit to activate the pump. If you've got 12v in the bay and 1v at the pump then you know it's the wiring that's at fault.

 

[jepherz]

Also ohm the power wire (either at the pump or the test connector under the hood) out to ground to make sure it's not a short before you just go throwing 12 volts on there.

 

[alik]

I'm ashamed to admit, but when it comes to the electrical stuff, it's a little scary to me. I have no issues tearing apart brakes or a diff, but electrical, well...
I've rebuilt the grommets at the pump plate, and ran the power from the battery. Pump works.
But, after reading and re-reading the VFAQ, I'm still utterly confused. Where is there a relay?

As far as I understand, I'm going to run a 10AWG wire from the battery with an inline 20A fuse to the pump pickup. Ground is good at the pump, and the only two other wires are the fuel tank gauge.

Am I missing something? (Besides a brain, that is)
/ubbthreads/images/graemlins/smile.gif

 

[strokin4dr]

You need to add your own relay if rewiring the pump. There are many how to's on doing this.

 

[alik]

Aaah!
NOW I get it! /ubbthreads/images/graemlins/smile.gif

Thanks!!!

 

[slowpoke]

I had this problem also. Ohm the ground wire on the pump harness from the connector to the STUD of the ground source on top of the pump assembly. Checking it at the end of the wire of my car it checked fine until I check it at the stud and it gave me a a** load of resistance. I cut the eyelid off ran a new wire and eyelid to the bolt/nut of the tail light assembly and the car started right up. Just a thought.

my post

click

 

[alik]

Well, I got the pump running.

Still can't figure out how the gauge is supposed to be connected (fuel level). Does it matter where the + and - go? Or, does the gauge simply look for resistance, and, therefore, it doesn't matter how it's hooked up?

(Car still won't start, however). /ubbthreads/images/graemlins/frown.gif