I have a 93 fzj80. I was idling last Sunday in my yard while I was loading up for a day out wheeling. When I came back to the rig after 5-10 minutes or so it was no longer running. It would cranked over but wouldn't start. So staring with the easy stuff I stared going through fuses with my fluke. The EFI fuse measured open. Upon removal the fuse went flying out of my hands. When I picked it up is was noticeably deformed from heat. Long story short I went on mud later that night and came across @scrowley post:
First time my 80 has let me down/towed
following this I was sure I would have had something similar. After I replaced the fuse the rig started just fine. It ran rough at idle for a minute or two but went back to normal fairly quickly. I felt the EFI fuse after several minutes of running and it was hot, also the EFI relay was almost too hot to touch (the round metal one). After reading @scrowley & @landtank 's thread(s)I removed the fuel pump relay, burnished the contacts and tried running it again. No change in running and the fuse and relay are still getting very hot. I purchased one of those harbor freight fuse testers to monitor the current that the EFI fuse was seeing:
30 Amp Automotive Fuse Circuit Tester
I observed when I would turn the Key to the on position but not crank it there was .3 amps on the testers display. When I crank the engine and it starts the current rises quickly to 8 amps then climbs to about 14.9 amps in seconds. Then as the rig idles down to approx 650 RPM's the current on the EFI fuse slowly drops from the 14.9 to about 12 amps after several minutes.
I am going to make a list of all the circuits that the EFI fuse supplies and try to see if I have a poor connection somewhere along the line or if I can disconnect some of these downstream sensors, relays etc. to see if the high current draw drops down. The problem is likely a connection somewhere that has degraded. Unfortunately, I think disconnecting some of these items will cause the vehicle to shut off and prevent me from identifying if they are the source of the high current draw.
FWIW I measured my wife's 80 EFI fuse current at startup like I did on mine mentioned above and observed it to climb to 8 amps and stay there indefinitely +/- a couple tenths of an amp.
Good thing I bought that EWD. It has already saved me a few times lets hope it helps again.
First time my 80 has let me down/towed
following this I was sure I would have had something similar. After I replaced the fuse the rig started just fine. It ran rough at idle for a minute or two but went back to normal fairly quickly. I felt the EFI fuse after several minutes of running and it was hot, also the EFI relay was almost too hot to touch (the round metal one). After reading @scrowley & @landtank 's thread(s)I removed the fuel pump relay, burnished the contacts and tried running it again. No change in running and the fuse and relay are still getting very hot. I purchased one of those harbor freight fuse testers to monitor the current that the EFI fuse was seeing:
30 Amp Automotive Fuse Circuit Tester
I observed when I would turn the Key to the on position but not crank it there was .3 amps on the testers display. When I crank the engine and it starts the current rises quickly to 8 amps then climbs to about 14.9 amps in seconds. Then as the rig idles down to approx 650 RPM's the current on the EFI fuse slowly drops from the 14.9 to about 12 amps after several minutes.
I am going to make a list of all the circuits that the EFI fuse supplies and try to see if I have a poor connection somewhere along the line or if I can disconnect some of these downstream sensors, relays etc. to see if the high current draw drops down. The problem is likely a connection somewhere that has degraded. Unfortunately, I think disconnecting some of these items will cause the vehicle to shut off and prevent me from identifying if they are the source of the high current draw.
FWIW I measured my wife's 80 EFI fuse current at startup like I did on mine mentioned above and observed it to climb to 8 amps and stay there indefinitely +/- a couple tenths of an amp.
Good thing I bought that EWD. It has already saved me a few times lets hope it helps again.