EFI Fuse repeatedly blowing....HELP !!

[MKIIISupraGuy]

OK so some of you know the issues I was having after gettting my motor back in, and with the alarm triggering and what-not. I had the car running but when I went to drive it I got several miles from the house and it stalled out on me. I have found that the efi fuse keeps blowing and I can't figure out why. It blows as soon as I try to crank the car. I know it's probably a short, I just don't know where. Please help, I really would like to be able to drive my Supra again, it's been almost 2 months.

 

[Mynes_3]

Check to see if your o2 sensor harness is grounding anywhere on or near the turbo cause thats what happen to me and i found put that the harness was grounded.

 

[airhead04]

^this

 

[fonz87]

Check to see if your o2 sensor harness is grounding anywhere on or near the turbo cause thats what happen to me and i found put that the harness was grounded.

that or unplug your CPS plug and plug it back in. i didn't have the CPS plugged in and went to start it, and the EFI fuse blew on me. you probably have a bad 02 sensor.

 

[MKIIISupraGuy]

Wow I would never have thought of that, I will check it out and post results

 

[MKIIISupraGuy]

Ok the O2 harness was not touching and made sure it was routed via the 2 retainer clips. I unplugged the cps connector and then plugged it back in. I hit the key and...it blew the fuse.

 

[ihiryu]

I remember there's another harness that also causes it to blow, I think it's for EGR? I remember doing a search via google by typing "site:supramania.com "EFI Fuse" and it came up

 

[MKIIISupraGuy]

Thanx yea I been reading all the previous threads. So far everything talked about I have already checked.

 

[jetjock]

Yeah, a common chafe point is near the EGT where the harness can contact the manifold. If it's popping the fuse when the key goes to start it and, assuming it's not hard shorted somewhere else, it could also be the fuel pump circuit. You might want to gently move the harness around and see if that stops it. If not there's always the light bulb trick.

Btw it's impossible for the CPS to be involved...

 

[northwestsupra]

if im reading the electrical diagrams it could also be
vsv for intake
vsv for EGR
ISC valve
02 sensor
check connector
MAF
Radiator fluid level switch
Ground point on left fender

 

[jdmfreak]

When I had this problem in my truck I bought a 20 amp circut breaker fuse it saved me a fortune in having to replace fuzes....turn on ignition breaker trips turn off ignition wait a few seconds breaker auto resets good to try again...

Sent from my DROIDX using Tapatalk

 

[MKIIISupraGuy]

Yeah, a common chafe point is near the EGT where the harness can contact the manifold. If it's popping the fuse when the key goes to start it and, assuming it's not hard shorted somewhere else, it could also be the fuel pump circuit. You might want to gently move the harness around and see if that stops it. If not there's always the light bulb trick.

What's the light bulb trick?

Btw it's impossible for the CPS to be involved...

See that's what i was thinking, I knew I was'n t losing my mind lol

When I had this problem in my truck I bought a 20 amp circut breaker fuse it saved me a fortune in having to replace fuzes....turn on ignition breaker trips turn off ignition wait a few seconds breaker auto resets good to try again...



Sent from my DROIDX using Tapatalk

Yea I know how they work, but it does'nt fix the reason it's blowing....

 

[jdmfreak]

I know but it made trial and trial searching a lil cheaper ... my o2 sensor wire had landed on my exhaust I know you had already checked and it wasnt that. I just wanted to throw that little trick out there in the off chance you didn't know so you didnt end up with a coffee can full of dead blue fuzes

Sent from my DROIDX using Tapatalk

 

[JPsToyota]

Might want to look for just general rubbing on your harness, maybe where it goes through the firewall or other points in close contact with metal.

Could it be the fuel pump wiring on that fuse?

 

[toyotanos]

I have seen many wire harnesses pinched at intake manifolds- I would check around the upper and lower intake manifolds since many of the things in that area are powered by the EFI circuit.

 

[MKIIISupraGuy]

I know but it made trial and trial searching a lil cheaper ... my o2 sensor wire had landed on my exhaust I know you had already checked and it wasnt that. I just wanted to throw that little trick out there in the off chance you didn't know so you didnt end up with a coffee can full of dead blue fuzes

Sent from my DROIDX using Tapatalk

thanx I appreciate the input

Might want to look for just general rubbing on your harness, maybe where it goes through the firewall or other points in close contact with metal.

Could it be the fuel pump wiring on that fuse?

I guess it could be, I'm no expert though. I know its not the firewall entry point though

I have seen many wire harnesses pinched at intake manifolds- I would check around the upper and lower intake manifolds since many of the things in that area are powered by the EFI circuit.

I have'nt looked there yet, but it's next on the list. I have the harness routed back just like before I pulled the motor. It amazes me that I might have missed one little detailed turn at the intake manifold, and it cause all these problems.

 

[hvyman]

The light bulb trick is much cheaper than buying a circuit breaker. It works excellent as well. Just add wires to the stock headlight on the power and ground prongs and insert the wires into where the fuse is. Turn the key to on and the light should be on. Move around the harness and if it goes out then you found where the problem is. (iirc been a while)

 

[Nick M]

You can also put a test light between the ground cable and terminal. When the light goes out, you found the short. Remove the fuses one at a time to narrow the circuit.

 

[jdmfreak]

The light bulb trick is much cheaper than buying a circuit breaker. It works excellent as well. Just add wires to the stock headlight on the power and ground prongs and insert the wires into where the fuse is. Turn the key to on and the light should be on. Move around the harness and if it goes out then you found where the problem is. (iirc been a while)

How do you keep the car in crank mode while your checking the harness??

Sent from my DROIDX using Tapatalk

 

[3p141592654]

With the IGN on, just wiggle the harness looking for rub points that blow the fuse. The starter is just causing the engine to move around, and you can usually get the same effect by moving the harness.