80-series 93' Crank no Start unless I reset ECU (Computer) (1 Viewer)

[Rudyoc23]

Hi all, first time posting, many times visited. I have an issue with my 93 FJ80. Every week and a half to 2 weeks, the rig will not start. It does this only after it has sat overnight. I remove the EFI 15 amp fuse and the EFI relay for a few minutes to reset the ECU (Computer) and then it starts fine for another week and a half to 2 weeks. Has anyone come across this intermittent problem? Any suggestions on how to fix permanently?

Thanks, RC

 

[Marco Lau]

Welcome
Can you explain the no start issues in details?
BTW your 93 is a FZJ80.

 

[Rudyoc23]

Welcome
Can you explain the no start issues in details?
BTW your 93 is a FZJ80.

Yes, correct, my mistake. I always search it as FJ80, ha.

It happens randomly. It starts fine for days until randomly one morning it will just crank but won't start. The first time it did this to me, it sat for weeks because I could not figure it out. Tested fuel pump, changed out fuel pump relay and it would not start. I reset the computer by removing the relay and fuse and it started. Now it has does this to me about 10 times now and I temporarily fix it by resetting. Works fine, until it doesn't, and I have to reset.

 

[voodu3]

Do you have cel with the key on?
Does the cel ever flash?
Have you tried to see if there are any codes in the ecu?
My guess is it’s an electrical problem or failing ecu.
Have you checked your grounds and the condition of your wiring harness?

 

[jonheld]

Yes, correct, my mistake. I always search it as FJ80, ha.

It happens randomly. It starts fine for days until randomly one morning it will just crank but won't start. The first time it did this to me, it sat for weeks because I could not figure it out. Tested fuel pump, changed out fuel pump relay and it would not start. I reset the computer by removing the relay and fuse and it started. Now it has does this to me about 10 times now and I temporarily fix it by resetting. Works fine, until it doesn't, and I have to reset.

All that is needed to reset the ECU is to remove the 15 amp EFI MAIN fuse. Removing the relay does nothing as far as the ECU is concerned.
As stated above, the CEL should be illuminated with the key in the ON/RUN position before cranking the starter. No CEL=no start. The most common reason is failing fusible links off the positive battery terminal. It is also possible that simply reseating the EFI relay allows it to make better contact with the terminals in the fuse box. If that's the case, then tighten the female connectors.