Hot Wire/Jump a fuel pump? - Toyota 4Runner Forum

aa010175 · 01-01-2023, 12:38 AM

I have fuel leakage from the injectors to the fuel railings. 4 or 5 of them are leaking. I would like to replace the bad O-rings and then test out the fuel railings and pressure prior to putting the whole upper engine back together and again finding out it’s still leaking. Is there anyway to activate the fuel pump without the engine running? Thanks Dave

rcvxl24 · 01-01-2023, 02:44 AM

Quote:

Originally Posted by aa010175

I have fuel leakage from the injectors to the fuel railings. 4 or 5 of them are leaking. I would like to replace the bad O-rings and then test out the fuel railings and pressure prior to putting the whole upper engine back together and again finding out it’s still leaking. Is there anyway to activate the fuel pump without the engine running? Thanks Dave

Yes, if you have an extra battery laying around (car, lawnmower, etc) you can hook the leads up to the fuel pump and jump it.

Sent from my iPhone using Tapatalk

gamefreakgc · 01-01-2023, 08:28 PM

There is a way from the diagnostic port but it has been a very long time since I have done it on a Toyota. +B is the fuel pump power wire you just have to ground it and I don't know which is the diagnostic port ground. Be sure to have some spare fuses on hand as if you get it wrong the fuse will blow.

aa010175 · 01-01-2023, 08:57 PM

Do you mean the test port that it’s under the hood? I found B+. Are saying to just ground it out and the fuel pump will run? Thanks Dave

gamefreakgc · 01-01-2023, 09:34 PM

Quote:

Originally Posted by aa010175

Do you mean the test port that it’s under the hood? I found B+. Are saying to just ground it out and the fuel pump will run? Thanks Dave

Yes the Test/Diagnostic port under the hood. I just don't remember which is ground. You'll hear it run if it works. Like I said though, don't strand yourself and make sure you have replacement fuses. E2 used to be the ground on old Toyotas but I didn't see one labelled as such last I checked. You'll ground it by running a paper clip or small section of wire from +B to the ground wire on the diagnostic port. I suppose you could try just connecting it to the ground right there on the side of the intake and see if that does it.

Once you have the correct ground turn the key to "On" but don't start the engine. You should hear the pump run if it works.

aa010175 · 01-01-2023, 09:47 PM

Quote:

Originally Posted by gamefreakgc

Yes the Test/Diagnostic port under the hood. I just don't remember which is ground. You'll hear it run if it works. Like I said though, don't strand yourself and make sure you have replacement fuses. E2 used to be the ground on old Toyotas but I didn't see one labelled as such last I checked. You'll ground it by running a paper clip or small section of wire from +B to the ground wire on the diagnostic port. I suppose you could try just connecting it to the ground right there on the side of the intake and see if that does it.

Once you have the correct ground turn the key to "On" but don't start the engine. You should hear the pump run if it works.

Thanks so much for the information. I will give it a try and report back. Dave

aa010175 · 01-01-2023, 11:24 PM

Here’s the photo I found to use’s.

gamefreakgc · 01-03-2023, 03:20 PM

Quote:

Originally Posted by aa010175

Here’s the photo I found to use’s.

Did jumping those terminals work? Toyota must have changed their diagnostic procedures at some point.

phattyduck · 01-03-2023, 05:53 PM

On OBD-I Toyotas, jumpering Fp and B+ in the diagnostic port (same connector still used on the gen3 4Runner on the intake manifold) would power the fuel pump with the key ON. I'm not sure if the connections are still there in the connector on the 4Runner. Otherwise the fuel pump will only be powered with the key in START or the engine is actually running.

-Charlie

loneshepherd · 04-16-2023, 07:01 PM

Did that work? my 97 5VZ 4R doesn't have a pin to use in the Fp slot.

Site Navigation