Not getting enough volts at the fuel pump......need help

[4x4runrfan]

Hey everyone,
Maybe you've heard this happen before, maybe you haven't..........anyways, I just bought this 1992 4runner, 5speed, V6 recently. The guy told me that there was a leak in the fuel line and that's why it wouldn't run (I could smell the gas). When I got it home and started looking into it the fuel lines where fine but the tank was leaking. I took the tank out and found the leak (small), while I had it out I checked the fuel pump to see if it was working (I hooked up some leads from a battery, fuel started flowing). I sent the tank in to get it fixed/sealed. I get the tank back in and it just turns over.........no fuel. Pull the tank back out, leave the lines hooked up and hooked it up to a battery for constant power..........runs like a charm.

Now I take my volt meter to check for power from the wiring harness and I'm only getting 4.6 volts???????? WTF. I traced the wires to look for some brakes, nothing. I checked the relay under the hood (EFI relay), working good. There's full volts coming in and going out of the relay, as soon as I get inside the truck it's down to 4.6...........

I'm at a loss here, P L E A S E H E L P.

Thanks,
4r

 

[CJ3Flyr]

Bump/move

 

[carl johansson]

I certainly am very little help at electrical - but I'm pretty sure the signal from the EFI relay then runs through a 15 amp fuse in the fuse box - correct? So are you getting the correct volts after the fuse block?

Carl Johansson

 

[4x4runrfan]

Not sure......I'll check tomorrow. The fuse is OK.

 

[A/V1]

How's it going?

So do you have the wiring diagrams for your runner? That would be the first place to start for me - download everything you can. There's a Toyota wesite where you can download all that info I'll try to get it for you if you want it.

Anyway, I would work my way from the relay to the back checking voltage, seeing if there's a drop, & inspecting for corrosion. Also check for continuity, and the resistance of the wire between the relay & fuel pump. There may only be two or three junction breaks in-between the relay and the pump, but disconnect at each point and check from there (for voltage, corrosion, continuity, etc).
Obviously there's got to be corrosion or a damaged wire somewhere in there. Unless there's a resistor used (There's a fuel pump resistor on my 4th gen), you should have full power at the pump. Once again, you are guessing without diagrams.

Good luck!

 

[4x4runrfan]

if you could send me those diagrams that would be very helpfull.........thanks.

 

[A/V1]

if you could send me those diagrams that would be very helpfull.........thanks.

Sorry, I should have been clearer. What I meant was I could get you the website to download the diagrams. Unfortunately it's not free... But definitely helps. A 2 day subscription is $15. Month is $75. Used to be $10 & $50.


https://techinfo.toyota.com/techInf...Oc%3d&TARGET=$SM$https://techinfo.toyota.com/