No power at fuel pump

[Jorley]

Whats A Drive Line

If you are serious, the drive line(commonly called the drive train) are the components that transfer engine power to the wheels. It consists of clutch/torque converter, tranny, driveshaft and differential.

 

[Sunk]

I also tried grounding on of the leads from the multimeter and still got nothing.

 

[Jorley]

That's kinda weird. Sounds like a bad wire between relay and interia switch. Try this. With the relay and interia switch unplugged, run a wire from the org/Lt. blu wire at the relay to ground. At the inertia switch check resistance to ground. should read 0 ohms. If not, check both connectors for broken wires and/or corrosion.

 

[Sunk]

Alright, I'll check that. I think some friends are heading to the wrecking yard tomorrow, so I may try to snag a couple relays just for kicks.

 

[Sunk]

Ok, we tried like you suggested at got around 4.5 Ohms steady. I also picked up a new TFI, new relay and inertia switch at the junk yard. I tried it again with the new relay and with and without the different inertia switch. Still nothing. I would swap out the TFI, but I'd rather not have to mess with the distributor unless I know that's what's wrong.

 

[Jorley]

That's shows the wire is ok. 4 ohms is low enough for current to flow.
Check the connector at the fuel pump for broken and/or corroded wires.
Ground the org/Lt blu wire at the relay again and check the pnk/blk wire at the pump to ground. Should read low ohms. The blk wire at the pump should read low ohms to ground also. The blk wire is the ground for the pump.
The way that we have done the wires the TFI wouldn't cause the problem. We have set it up for power to run directly from the bat. to the pump.

 

[Sunk]

Checking the pink/black wire at the pump to ground, i saw as high as 24 Ohms, but it was all over the place. Checking the black wire, I got 10 Ohms steady.

 

[Jorley]

Ok. Lets take a step back and review what we know and what's been done.
Your truck started "bucking" most likely fuel starvation.
Not pressure at injector rail and no sound of pump running and no power at pump.
There is power on the yel wire at the relay.
Jumping the yel and org/Lt blu wires at the relay there is no power at the interia switch.
The org/Lt. blu reads 4 ohms between the relay and the inertia switch. Low enough for current flow.
Ok, For some reason the power is not getting to the org/Lt. blu wire from the yel wire.
ok, let's bypass the yel wire with a jumper from bat.(positive post) to the org/Lt. blu wire at the relay. Have the inertia switch and pump plugged in. Pump should run.
I'm sorry this is taking so long to figure out. With no pressure at the injector rail the computer should tell the pump to run, and since you changed the relay it must be a bad connection somewhere.

 

[Sunk]

Yeah, don't worry about it taking do long. Im sorry you have to hold my hand through this whole process, but electronics mystify me. I may take a crack at it later, but right now my patience is gone.

I'll let you know the results.

 

[Jorley]

Yeah, electronics can be intimidating. I learned electronics in the navy. You learn the meaning of stress when, during a live fire missle exercise, the unit commanders radar repeater goes down and he want to know why.

 

[Sunk]

OK, I jumped it from the battery to the orange/light blue wire, nothing. Im getting some help with this and we're trying to trace down how far the power goes. I have power at the fusebox, and made the pump run with a pin through the wire from a battery charger. I was even able to fire it up, but it died after the pressure dropped when we removed the lead from the charger.

 

[Jorley]

unplug th relay and the inertia switch and try the pin thing on the wires at the inertia switch. If it runs plug the inertia switch in and try pin at relay.

 

[Sunk]

Got it! In the process of checking continuity with pins, we were working our way across the fat harness that goes across the engine bay and discovered a place where the wire loom had most likely come in contact with the alternator pulley, cutting a groove in it. I pulled it apart and found the power wire to the pump ( I believe) had been cut near in half. The wire connections at the relay were also slightly loose, but I got it all fixed and its rolling again.

Thanks again for all the help!

 

[Jorley]

I'm really glad you got it fixed. And no problem about the help, that's what this site is here for. One day I may need your help with something. So happy motoring and drive safe.

 

[lodden758]

I had a prob with fuel pump power when threw and check all switches and relays, end up being the dum computer, dont know what it has to do with it but change it with one for a junkyard and fired rite up.