EFI Fuse Blowing -- Ideas? (2 Viewers)

[NorCalDoug]

Actual trip detais will follow later...but here's the situation...
My rig is at a Lexus dealership in Las Vegas (Lexus was the closest dealership and it was being towed there).

EFI fuse is blowing. Any ideas on where to look for shorts, chaffed wires, etc.?

Morgan Fletcher used to have a great write-up that illustrated what he went through in a similar situation -- I thought it was on birfield.com but the last time I looked, the tech portion of the site was non-existent. Anyone have this write-up?


The fuse blows as soon as I turn the key in the ignition.

As for what led up to the issue, we had just come off a road and were airing up. I connected my compressor to the battery, aired up my tires, disconnected the compressor, then walked over to another rig. When I returned, the rig was dead.

I had a similar problem with the EFI fuse blowing on the last rubicon trip, but that time, it "self corrected" -- we replaced the fuse a couple times and the problem went away.

 

[clownmidget]

Doug,
this was posted on the Lexus owner's list a while ago and is worth checking:

"I have had no major problems at all with any of my rigs -- well, that's not necessarily true -- with the '94 I had a problem with a section of wire coming from my O2 sensor. The insulation had rubbed off from 100k miles of vibrating against the firewall (one of the very few dumb design features). However, it was not a problem until I had the O2 sensors replaced. The mechanic had pulled the wire a bit when he reconnected everything. It became positioned in such a way that the exposed wire would occasionally come in contact with bare metal. This caused my EFI fuse to short out. Once we figured out what the cause of the problem was -- it was a very easy fix."

Good luck.

 

[NorCalDoug]

Thanks Mike.
I had some exhaust work done before I left for the trip, so that could be a good place to start looking. The rear O2 sensor was unplugged/reinstalled for the work.

I tried to trace it up through the engine compartment, but couldn't locate any actual chafing -- that said, it was getting dark when I checked that again and it was tough to see.

BTW, I think that's my post from that Lexus site

 

[yep]

Please be sure to post the root cause once it is known- it is KILLING me to know.

I must have missed the conversation regarding your recent exhaust work while we were "investigating"

Glad you made it home Safely- finally! (dumb a$$ tow-truck driver)

I look forward to the list of suggestions that get posted here...

-David

 

[spartan]

I recently had EFI fuse melt down. Socket and fuse actually melted. Happened during a downpour with deep water etc.

Replaced fuse and everything worked. Could not find any chafed wires.

The only thing amiss was that the fuse box was not assembled properly leaving an open gap along the bottom of the plastic pieces where they join together.

Corrected assembly of box. Completely cleaned and relocated EFI fuse contacts to new location. Greased contacts. No problems since.

Good luck.

 

[LEXUSBEN]

o2 sensors are probably a good start. I will mention that I have seen the fuel pumps on p/u and 4runners cause efi fuse to blow. Sometimes its intermittant and sometimes its not. Fairly easy to diagnose just unplug fuel pump at tank and see if fuse pops again.

 

[clownmidget]

Doug,
The wire routing for the fuel pump might be a good place to check especially the area where you'd normally unplug it when replacing the fuel filter. Your sliders or something else may have crimped a wire there?

 

[e9999]

sorry to hear this, Doug. Hope that didn't affect the trip too much.
Hope it works out quick.

 

[Darwood]

Doug, the one thing I wanted to try Saturday was to disconnect pin outs from the ECU until we found one that wouldn't blow the fuse when it was disconnected. That way you could isolate the system that had the trouble, however this could take some time since there are what over 100 pins in the ecu?

Anyway I still feel for you. How's Shelby doing?

note to self, get a wiring diagram manual.

 

[clownmidget]

note to self, get a wiring diagram manual.

definitely! and this makes me want to invest in the obd-II reader diagnostics kit for the laptop.

 

[rockclmbr]

Hang in there Doug. It was very frustrating to have all this knowledge in one place and not be able to fix it. This is very unlike our luck and group of great people. I am anxious to find out the root cause/fix also.

 

[NorCalDoug]

Doug, the one thing I wanted to try Saturday was to disconnect pin outs from the ECU until we found one that wouldn't blow the fuse when it was disconnected. That way you could isolate the system that had the trouble, however this could take some time since there are what over 100 pins in the ecu?

Anyway I still feel for you. How's Shelby doing?

note to self, get a wiring diagram manual.

That would've taken a LONG time.

Shelby's doing fine. A bit of an ear infection...looks like she had it before the trip. That explains why she was complaining about pain in her ear -- I thought it was likely due to the elevation change and her ears not equalizing.

If you're interested...I have a EWD for a 97. I think I'll pick up the Lex. version...for those little idiosyncrasies.

 

[mickey_rubicon]

there is a bundle of wires going into thre fire wall by the heater control valve near the intake manifold area it is for starting and ignition, it is prety hot in those parts; I had a nasty short there until I re-wired it and put heat resistant tape around the wire caging. If need I can post a picture where to take a gander.

 

[Darwood]

That would've taken a LONG time.

True, but we could have isolated it to the most likely suspects. I would have liked to pull at least the injector pin outs to eliminate those.

Shelby's doing fine. A bit of an ear infection...looks like she had it before the trip. That explains why she was complaining about pain in her ear -- I thought it was likely due to the elevation change and her ears not equalizing.

That's good that she's fine, albeit with an ear infection. So are you also in Vegas?

If you're interested...I have a EWD for a 97. I think I'll pick up the Lex. version...for those little idiosyncrasies.

Yep I'm interested. I'll buy it off you. Of course we already had this conversation didn't we.

 

[NorCalDoug]

...So are you also in Vegas?

No, not in Vegas anymore. Got picked up at 6:30PM. Driver didn't want to try to make it over the pass to Vegas on Saturday night -- I had to spend the night in Pahrump -- got the last room (literally) in town. Sunday morning consisted of driving toward Vegas, the flatbed's serpentine belt getting shredded; waiting for another flatbed; getting to Vegas; renting a car and driving the 10 hours home...trying desperately to not fall asleep at the wheel
Yeah...it's been an "interesting" couple of days.

...Yep I'm interested. I'll buy it off you. Of course we already had this conversation didn't we.

Yep...it's waiting for you. Whenever you're ready.

 

[NorCalDoug]

Am told by the dealership that I have a bad fuel pump and that's the cause of the EFI fuse blowing.

They suggested I grab ankle and hold on tight for a new fuel pump...I countered with a call to CDan...Dan's the man...but we all knew that already.

(to Lexus of LV for stealership prices)

 

[Cruiserdrew]

So how much? You can PM if the number is too large to fit in this space! Glad, though, that's all that is is. I'll be up this evening with your tire unless things go to ground here at work.

 

[NorCalDoug]

So how much? You can PM if the number is too large to fit in this space! Glad, though, that's all that is is. I'll be up this evening with your tire unless things go to ground here at work.

They gave me a $1350 estimate -- parts/labor.

Aprox $650 for the diagnosis and the install of the fuel pump. I knew that would be fairly high due to the Lexus glitziness and the higher shop rate...I'll eat that without too much complaint...not that I have much choice in that...

They wanted $700 for the fuel pump.



As for the tire...someone should be home, you can still leave it in front of the larger garage door, next to the large rosemary bush.

 

[clownmidget]

Oh, that hurts! And I still carry my original one with me since I replaced it with the supra one - I knew I should have gone up there Friday night!!!!!!

Glad you got it fixed but still make sure you don't have some bad wires leading to your fuel pump getting cooked.

 

[Beowulf]

Morgan Fletcher used to have a great write-up that illustrated what he went through in a similar situation [ .... ] Anyone have this write-up?

Doug,
It looks like the problem has been identified but I have a fairly clear memory on the details with Morgan's EFI fuse issue. (Other poster mentioned O2 sensor and that was Morgan's problem though there are more details...) FWIW, Morgan felt the problem was specific to the 93-94 models due to the routing of the wiring.

Let us know as this saga proceeds.

... Later ....

Found it! http://www.birfield.com/~morgan/tech/2nd_O2_wires.html

-B-