FJ80 no spark problem

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Something just popped into my dusty head. Has the battery been disconnected for any length of time since the start of all this trouble?

What I'm getting at is that it's possible the ECU is stuck in some stupid state due to the spike in voltage. It has a capacitor back up that will keep the current memory state for about 15 minutes or so. It might be worth disconnecting the battery for an hour or so just to see if that makes a difference.

Contact the folks who have done engine swaps from a 3FE and try to borrow a known good ECU. Contact cruiserparts.net and see if they have a 3FE ECU out of an FJ80 for sale. The ECUs from an FJ62 are a different part number IIRC. I might still have my spare in the garage somewhere. If I do you're welcome to use it for troubleshooting.
 
I have just swapped the alternator for a new (2nd) rebuilt unit. I got the spec-test sheet from the rebuilder, and it shows good output. The first one they tested and sure enough almost 20 volts max so they admitted the regulator must be at fault. I've gone back over all conections again with contact cleaner and then some dielectric grease. I left the battery disconnected for the whole day in hopes that the above post might work but no luck. I am getting a signal to the cold start valve but now loking at the diagram I see that that is controlled by a seperate time switch, and not the ECU. Is there one injector electrical plug that is easiest to get at? I was thinking that if I have a signal to the injectors, then the problem may be a dead coil. The sensor that has broken is either the efi water temp sensor, or the start injetor time sensor, as far as I can get from the diagram. I'll pull it on monday and take it to toyota for a new one. I may put a new coil in it just to see, and am wondering if anyone has a good ecu to loan, rent , or sell. I'll post an add in the wanted section. Does anyone know if the guys from up-n-over are still here? They're not far and have a barn full of cruiser stuff. Thanks for the help this far, Seth
 
So before posting again, I've done a fair amount of searching here and on other yota sites. Here's where I'm at, and a few things I've found elsewhwere (may need to be confirmed). The relay and all fuses and grounds are good. The distributor pickup reads proper ohms, so should be good. 12 volt to the B+ test terminal and the power lead to the coil-ignitor, key on. still no check engine light, and I cant get the light to flash any codes with the paper clip trick. I found that on other toyota vehicals, if the ignitor or airflow sensor get fried they can take out the CEL, can anyone confirm? Oh, I also have no signal to the fuel injectors. I read that on OBD2 toyotas, if the ecu doesnt get a signal back from the coil-ignitor, it will shut down the fuel injectors. Maybe that's my problem, I've also read that on some cars, the ecu will shut down if the check engine light is disabled. Maybe mine is burned out and this is the case? I've locared a few ECUs, and will pick up a new coil in the morning. If you can think of something here that rings a bell, please let me know. It's always things like this that get you familiar with all of the little sensors and relays, NOW I know what they all do. Thanks again, Seth
 
Seth;
U mentioned that the first alternator tested for 20 volts output. I'm going to guess that will fry the input to the ECU. Hate to say it, but a new ECU [or known good one] is the order of the day.

...
 
esde said:
I found that on other toyota vehicals, if the ignitor or airflow sensor get fried they can take out the CEL, can anyone confirm?
Click to expand...

Don't know from firsthand experience, but I doubt it. The AFM is a simple pot that tells the ECU the position of the plate. The ECU provides a fixed voltage to the AFM and TPS from pin 1 (VC). The AFM also has a thermistor for air temp.

I suppose it's possible that the ECU went into "Fail safe" mode and shut down spark and injectors. Either way swapping out a coil/igniter combo is easy and quick. The ECU is not difficult to get to either. I wonder if the lack of a CE light despite the EFI circuit functioning is the tell tale sign of this?

Good luck and keep us posted.
 
Tried the new coil and ignitor assemblies, and no luck. I found a computer in the DC area, and it should be here in the morning. Cost me $175 including next day UPS. They have it listed as out of a running truck, I'll cross my fingers. Seth
 
To close this thread, the new used ecu fixed the problem. It started and idled slowly at first, then picked up a few rpm and smoothed out. I plugged the old coil and ignitors back in and they work fine. I'll probably return the ignitor and keep the new coil as it does seem to idle smoother with it than the origional. I opened up the dead ecu just to see if anything was visibly fried and yes, there is one diode that melted right off of the board. It is labled T S5225 1-G and is a black tablet slightly smaller than an altoid. I will post a pic showing its location, labled position D105 on the board. I guess that if someone finds this post in the future, it is safe to assume:
If you have no check engine light but have power to the ecu, pull the 4 screws on the ecu cover and check diode D105.

Maybe this is the weak link that will burn out because of an overcharge-high volt situation. I may attempt to pick up a new diode and see if the board can be repaired, if it can be I'll update this. Many thanks to this board for all of the good info and advice that can be found, there is no better place to find cruiser tech IMO.

Seth 92 FJ80, 71 416 Unimog, 2003 Camry
IMG_2232.webp
 
jonheld said:
Leave the new coil/igniter in place and keep your originals as spares. I lost the igniter on mine and it is fairly common on older 3FEs.

Glad you're all fixed up!
Click to expand...

Good to know, Thanks.
 
Hey Jon and Seth,

I had them re-open this thread as I am living the dream so to speak. Details 91 FJ80 stock unmolested 3FE, 254k...:princess: was driving it yesterday went over RR tracks and it died. Thus far have done all the tests that Jon points out. I have 12v feeding the fuse/relay panel, I have 12v at the B+ pin, still no check engine light. Swapped out a relay from my 97...just in case and it was parked next to it, still no CEL. I am off to get it towed home now, as the joy of troubleshooting at the side of the road is well...you know. The only other thing I noted is that one the fuses up near the + battery post fuseable links was blown. Other than that a rebuilt alternator (by local reputable shop, rebuilt my original, Ploeners down in Wilmington) was dropped in back in October and was working flawlessly. So, I don't think there is an issue there. When I get it home, I will check the wiring from fuse to relay more closely and open up the ECU and look at the diodes. Any other thoughts ?
 
Hey Jon,

I tried all the procedures...and then I pulled the ECU and opened it up just before lunch. It is exactly the same as Seths...D105 completely melted off. Dropped and attached itself to the cover. Making me wonder a few things. Seth lives nearby and had his alt rebuilt (possibly the same outfit that did mine). Although, since October when I installed it, when I drive the grey wagon, which is like 95% of it's use, I always eyeball the gauges and have not noticed anything other than normal ops. That's not to say it couldn't have had a spike when :princess: was driving. I am going to look for a diode and replace it...although something else could have fried in a less dramatic fashion. I'll be looking for a good used ECU as well. I'll update this as to the outcome of the diode replacement and new/used ECU hunt as well. Maybe Schmuck has one laying around.
 
That would be a pretty wacky coincedence if it were true. If Gary doesn't have one Jason from Cruiseryard.com probably does.

Good luck and let me know how the repair goes. If you get into a jam, I think I still have an extra from a 92 buried in a box somewhere in my garage. IIRC it works fine.
 
Yes that would be wierd. I've sourced an ECU out of a 92. It will be awhile before it arrives. In the interim, I'll hunt down a diode and replace the fried one and report back, although I think that is the tip of the iceberg in the ECU...we'll see. Reading back through this...it is truly uncanny. Seth hasn't been on board since 2009, but I did try to send him an email. I'd like to know who rebuilt his 1st (and 2nd) alts and how long did no. 2 rebuild last or did it eventually cause any of the same issues. I am considering pulling this alt off and sending it back to the rebuilder and having it checked out before I plug the replacement ECU in there. Thats about it for now. Crazy stuff.
 
Paging Dr. Held...
Well I was all fat stupid and happy finding the "cause of my problem was the fried diode D105". That was until Friday on my way home from work. Turned a corner shudder and died. No restart. CEL illuminated when ign was turned to the on position, so I figured the D105 issue hadn't resurfaced. So after two months the grey wagon has left me stranded again about a mile from home. ECU relay wasn't noticeably hot but after the :princess: rescued me I snagged the relay out of the 97 just in case. Not the relay. So, after getting it drug home, I was off to eat some mexican food and have some cold beverages. So, around 3 today I found the motivation to go out and investigate. Popped the hood, eyeballed some things and then turned the key. Started right up....Not enjoying paying towing bills, I decided to let it sit in driveway and run for a while. After an hour or so went out and checked it...it turned itself off. And it will not restart. I'm going to let it cool for another hour or so and then see if it restarts. Any ideas ?
 
Did you ever consider your distributor? Have you checked it? If you are getting the proper voltage to it, I would test it and see if it is operating properly.
 
All things are to be considered at this point including distributor and coil/ignitor. So far I haven't had a chance to get back to it. Only new info is that after it died in the driveway again, I let it sit for 2-2.5 hours went back out, turned the key and it restarted. So, it is a rather strange occurence that seems to be linked to run time. When I get back to it, I will fire it up in the driveway....let it run until it dies then start with the basics...check for spark at the plugs and fuel arriving. Based on that outcome, I'll go down the path thats indicated. I am thinking it is electrical related not fuel related due to the fact it seems tied to run time. ie. something is heating up and causing an ignition cut out. Maybe get to it some this weekend.
 
I had a bad fusible link at the battery which looked good (outside) but wire was making intermittent contact; replaced all of them and fixed my starting problem.
 
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