‘93 FZ80 Engine shuts down randomly only after it’s warmed up… (2 Viewers)

[Andrew Bluemel]

I gave my 2 cents on it being potentially the wiring harness by the firewall because I THOUGHT that is what was causing my cruiser with similar symptoms to randomly die, as I was getting the truck to run again when jiggling the wires against the firewall. It must have just been a very random coincidence as I just spent 3 not very fun days replacing the whole harness and am having the same problem. I also just replaced my fuel pump as I figured since it only happens when it’s warm and the poor original pump has been feeding a supercharger for the last 30,000 miles that it might make sense. Nope. At this point all my fuel stuff is up to date so now I too am starting to look more closely at each specific sensor. Anyways, just thought I would share my update this has been a good thread to keep me questioning my truck and it’s good to see it seems you are slowly closing in on what your problem is.
Cheers!

 

[Nbndallastx]

Sorry for the crickets this week…I was out of town for work all week but huge developments on the solve - we worked on it this afternoon, no shutdowns this evening…still need to test drive over this wknd to confirm…trying not get too excited! More to come…

 

[Nbndallastx]

Ok - 3rd day of test drives and running the 80 hard…no forced shutdowns, since the fix

This was the issue, after 5wks of troubleshooting…PO had rigged a janky metal screw for ground within the fuel sending unit! It had rusted so bad that it had intermittent ground and would cutout…also the wires from the pump weren’t protected and the crimped looked old so we reconnected them and shrink wrapped them too!

When I first replace the pump February 2022 I didn’t notice the DIY ground and did question the wires connection but didn’t think twice about it, once the rig was buttoned up…also transparently didn’t know as much about cars as I do now…I know it’s only been a year but I know much more now lol. In reality, I think this was always my issue in the tank…

I’m guessing the intense Colorado trip was the final straw that broke the camels back when we got back. I couldn’t run the car once at temp for more than 7-8mins before it would short out and engine would die…

anyways huge thx to anyone who commented on this thread I’m still a noob mechanic but so happy I didn’t take it to a pro shop and really appreciate the journey to learn this rig’s system…until the next issue, cheers !!!

 

[RodrigzCrzr]

Wow!
That’s great you kept at it. It always seems to be the little things that make a big impact on function.
Glad you found it and made the necessary repair.

 

[billymagg]

Ok - 3rd day of test drives and running the 80 hard…no forced shutdowns, since the fix

This was the issue, after 5wks of troubleshooting…PO had rigged a janky metal screw for ground within the fuel sending unit! It had rusted so bad that it had intermittent ground and would cutout…also the wires from the pump weren’t protected and the crimped looked old so we reconnected them and shrink wrapped them too!

When I first replace the pump February 2022 I didn’t notice the DIY ground and did question the wires connection but didn’t think twice about it, once the rig was buttoned up…also transparently didn’t know as much about cars as I do now…I know it’s only been a year but I know much more now lol. In reality, I think this was always my issue in the tank…

I’m guessing the intense Colorado trip was the final straw that broke the camels back when we got back. I couldn’t run the car once at temp for more than 7-8mins before it would short out and engine would die…

anyways huge thx to anyone who commented on this thread I’m still a noob mechanic but so happy I didn’t take it to a pro shop and really appreciate the journey to learn this rig’s system…until the next issue, cheers !!! View attachment 3129800

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Nice job of sleuthing your 80's fuel/electrical system.

 

[Nbndallastx]

Wow!
That’s great you kept at it. It always seems to be the little things that make a big impact on function.
Glad you found it and made the necessary repair.

So true and thx! Glad to have my 80 back!!

 

[80t0ylc]

Ok - 3rd day of test drives and running the 80 hard…no forced shutdowns, since the fix

This was the issue, after 5wks of troubleshooting…PO had rigged a janky metal screw for ground within the fuel sending unit! It had rusted so bad that it had intermittent ground and would cutout…also the wires from the pump weren’t protected and the crimped looked old so we reconnected them and shrink wrapped them too!

When I first replace the pump February 2022 I didn’t notice the DIY ground and did question the wires connection but didn’t think twice about it, once the rig was buttoned up…also transparently didn’t know as much about cars as I do now…I know it’s only been a year but I know much more now lol. In reality, I think this was always my issue in the tank…

I’m guessing the intense Colorado trip was the final straw that broke the camels back when we got back. I couldn’t run the car once at temp for more than 7-8mins before it would short out and engine would die…

anyways huge thx to anyone who commented on this thread I’m still a noob mechanic but so happy I didn’t take it to a pro shop and really appreciate the journey to learn this rig’s system…until the next issue, cheers !!! View attachment 3129800

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View attachment 3129802

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So it did turn out to be electrical and fuel at the same time, bad ground caused the fuel starvation. Wow, way to hang in there! That's the way tough problems are solved, through persistence. The quote, "persistence and determination, alone are omnipotent" has always haunted me since I first saw it:

 

[Nbndallastx]

Just wanted to update the group here, for ppl who aren’t on IG, day #5 no engine shut downs since the fix! 3 of the 5 days were +200 miles round trip commutes to San Antonio- no issues

 

[robnicko]

Just wanted to update the group here, for ppl who aren’t on IG, day #5 no engine shut downs since the fix! 3 of the 5 days were +200 miles round trip commutes to San Antonio- no issues

great to hear & even better that no spark was produced within the tank when low on fuel and heaps of vapour around !!

 

[jbee]

Just wanted to update the group here, for ppl who aren’t on IG, day #5 no engine shut downs since the fix! 3 of the 5 days were +200 miles round trip commutes to San Antonio- no issues

Congrats!!
Glad to hear it was a poor repair that took the truck down and not some longevity issue lurking in all of our rigs!!
Great job on this!

 

[Nbndallastx]

1.5week update…

So for the last 11days I’ve been driving the fzj80 to San Antonio which is almost 200miles round trip each day from Austin…so since the repair we’ve done over 2000miles no issues until yesterday!

Yesterday morning it was 60ish degrees at 6am and the pump wasn’t getting power even with the “+B & FP” jumper…check out the link for video.



But…once the temps rose all day at 5pm, same day, I tried turning over the car and fired right up!

My guess is my fuel pump bracket is too rusty and with cool weather it’s not conducting electricity very well…is that what y’all think given this update?

I’ve ordered a new fuel pump bracket from Toyota part # 23206-66900

Talk to me Goose…thoughts???

 

[Nbndallastx]

I suggested this because it’s a quick test without tearing a bunch of stuff apart. Providing 12V directly to the fuel pump bypasses the whole fuel pump logic that comes from the ECU and forces the fuel pump to run. This assumes power to +B which can easily be checked with a meter, should have 12V with key on. Doesn’t necessarily mean the resistor is the problem. It may also be a way to get the truck running if it won’t start.

One thing to keep in mind is jumping the fuel pump means you have power with key on and not just when cranking/running. Worse case is you get in an accident with the pins jumped, rupture a fuel line, and the pump keeps pumping fuel.

I went through a similar issue with my SC400 where it would just die while driving. Jumping FP and +B always allowed it to start. I tracked the problem to the fuel pump ECU which I replaced and that solved the problem. The SC ECU is a little different than the Land Cruiser resistor but similar. In the SC world, many run with the fuel pump ECU bypassed, meaning power to the fuel pump with key on.

well just tested +B and now not getting 12V with the key on

CEL is lighting up, so not an ERI Relay issue

Thoughts? going through the fuses currently...

 

[Nbndallastx]

well just tested +B and now not getting 12V with the key on

CEL is lighting up, so not an ERI Relay issue

Thoughts? going through the fuses currently...

really weird...i disconnected the fuseable links to inspect them...they looked great (they're brand new a month old)...put everything back together and it fired right up?

maybe a bad connection and when i messed around with the wires it sorted stuff out...anyways, we'll see how the rest of this week goes...

 

[Nbndallastx]

It’s been a few months and just wanted to confirm that the new OEM sending unit had solved all my random shut off issues to date!

the culprit was the electrical connections in the sending unit…first the ground but also there was corrosion on the leads inside the epoxy - I tried to reseal but didn’t work. Took a ton of troubleshooting and didn’t know what I didn’t know.

Anyways just wanted to wrap up this tread with a bow