Blowing EFI fuse under hood when climbing. (1 Viewer)

[TN_LandCruiser]

Recently I was out wheeling some rocks and had the truck approx 30 degree angle when it suddenly died. After some searching, found that the EFI fuse had popped. I replaced it and it ran fine. Well since then I have probaby put 300 road miles on it with no issue...except when I went out wheeling a few weeks ago, I was climbing a rock ledge and blew 5 fuses before I got to the top. Seems like when Im in 4 low and give it any sort of gas, it pops. Again that was on some pretty extreme inclines...

Well several highway miles and no issues later, actually forgot about it and went wheeling again...this time, even the slightest incline seems to pop the fuse. Actually ran out of fuses and had to start pulling them from things like stereo and wipers just to get home.

It does it whether the CDL is engaged or not...only thing I havent tried it to find out if it does it in 4H too...but Im normally not climbing anything in 4H.

Anyone ever have this problem and or have any idea's what it could be? Thanks!!!

 

[BenMara]

is always the EFI fuse? sounds like its grounding some were along the harness fuses just save the wiring harness

 

[TN_LandCruiser]

Nope...its always the exact same 15a EFI fuse. Nothing else has blown. I even tried changing it to a 20a and its still blows just as fast.

 

[The Nak]

...its grounding some where along the harness...

I concur.

Nak

 

[Michael Hanson]

The wiring has gotten hard and brittle under your fuse box I bet. I had to rewire mine, Toyota used too small wiring under the fuse box. At least its worth a look, Mike

 

[Gumby]

I seem to remember a wire by the EGR tube that gets chafed too.

 

[Ebag333]

I even tried changing it to a 20a and its still blows just as fast.

Simply upping the fuse size usually falls in the category of "a really bad idea".

(You probably already know that, but it had to be said. )

 

[Michael Hanson]

Toyota makes a repair for this by swaping in new spades and wires for the EFI to plug into.Get the short ones and up-grade to 12 gauge tin coated marine wire. Mike

 

[TN_LandCruiser]

Simply upping the fuse size usually falls in the category of "a really bad idea".

(You probably already know that, but it had to be said. )

LOL...yeah, I knew that...but I needed to get out of the woods and thats all I had left...had blown the rest of my 15a fuses.

 

[Grolar]

Did you have a look underneath the engine? I had a loose wire in the undercarriage that touched the driveline and blew the EFI everytime I was braking. Looks much like your problem.
Thanks to Mud, that was diagnosed from afar and fixed. A $1 repair.

 

[TN_LandCruiser]

Did you have a look underneath the engine? I had a loose wire in the undercarriage ...

Grolar, Can you be a little more descriptive? That would seem to be a viable solution, but how did you find a lone wire? Was it something specific?

 

[TN_LandCruiser]

Toyota makes a repair for this by swaping in new spades and wires for the EFI to plug into.Get the short ones and up-grade to 12 gauge tin coated marine wire. Mike

Michael, can you give me a little more detail about this? Im by far an electrical guru. What harnass? Where does it connect?

Where is the EFI connection located?

 

[MoJ]

Anyone ever have this problem and or have any idea's what it could be? Thanks!!!

Unless I'm missing something your problem sounds like the very well known EFI wiring issue that is present with 91-92 FJ80's with the 3FE. IIRC it happens during high temperature situations. Crawling in 4L would certainly fit. There's a fix for it...here's one thread.

https://forum.ih8mud.com/80-series-tech/229877-efi-fuse-blowing.html

Use the search feature and you'll find several others. Try searching various combinations of EFI 3FE FUSE WIRING, etc. Years ago it was a common topic for 3FE owners. I haven't seen it brought up as much lately.


Good luck.

 

[Grolar]

Grolar, Can you be a little more descriptive? That would seem to be a viable solution, but how did you find a lone wire? Was it something specific?

Well, this was quite straightforward when the rig was lifted: a loose (+) wire was rubbing the steering column under the truck and got the metal exposed. Every time I was braking, the wire touched the ground and the EFI fuse blew. Someone here dug up a pic of the same problem at the time (fall 2006 I think) wondering if it's still around?
Also, my rig is a 94. Don't know if this kind of design flaw is relevant to 3FEs.
Good luck.

 

[jonheld]

Popping fuses under motor torque is not a comon symptom of the 3FE EFI wiring issue. It is certainly possible that there is a short in the fusebox, but I would expect to see that almost always, not in specific conditions.

Considering it only happens when in low range under load, I would suspect a chaffed wire somewhere. The motor moves a whole lot more in low range than it does in high and the body would be flexing as well in the given situation.

The EFI fuse feeds a host of items: "The load side of the EFI relay feeds +12 to the ECU (EFI on logic), all 3 VSV valves, both O2 sensors, the ISC valve, pin 8 on the Check Connector, and the load side of the circuit opening relay which feeds the fuel pump when the motor is running."

A short to ground anwhere in this system will pop that fuse.

 

[TrickyT]

I'd start by checking the O2 sensor wiring for a frayed wire. I've seen more than one truck with an O2 sensor cable that rubs against the chassis under torque and blows the EFI fuse.

 

[Grolar]

I'd start by checking the O2 sensor wiring for a frayed wire. I've seen more than one truck with an O2 sensor cable that rubs against the chassis under torque and blows the EFI fuse.

I second that. The 02 sensor wire was at fault in my case as well.

 

[Sc0-]

What he said, I remember the thread where the EFI fuse kept popping because of the 02 sensor wire was grounding out...

 

[Michael Hanson]

I agree with all of the above.however I find that the wiring under the exterior fuse box is too small and ages quickly due to the heat of the engine.I rewired under my fuse box and highly recomend it.

 

[elhombre]

I third that. Wheeling with a friend and he had a fuse blow after climbing over a steep hill also. Seems that a stick that was at the top off the hill jammed up into the O2 sensor wire and shorted it out. Dumb stick.