I really need some help diagnosing an intermittent problem on my '92 FJ80.
It currently has 217k, and I've owed and maintained it for the past 7 years.
Early this year I started having a strange, very intermittent problem. While driving, RPM suddenly drop to almost nothing but the engine does not die. After a few seconds RPM comes back and the truck runs like normal again. It "feels" like it's lost fuel, then suddenly comes back. There does not appear to be any rhyme or reason to the issue, it has happened in cold weather, hot weather, freeway speeds and surface streets.
I've recently replaced the fuel sock, fuel pump(while I was in there) and fuel filter. I also tested the AFM and TPS per the FSM and they both checked out. None of these things fixed the problem.
Fast forward to Tuesday. After getting home from a 45 mile drive, I jumped back in to run a quick errand. Truck fired right up drove about 50 yards sputtered and died. Cranked it a few to and got no start. I pushed it to the side of the road cranked it again and it fired right up. At the time I talked myself into thinking this happed due to being low on fuel and being backed up on an incline (wishful thinking).
Last night, it happened again. This time in traffic on the freeway. I was able to coast it to the side of the road but this time it would not start. I started going through possible problems. Key on, CEL on solid, so EFI is good. Cracked the banjo on the fuel return line, cranked starter, no fuel. Jumpered the fuel pump, cranked starter, got fuel! I tightened up the banjo bolt and limped it a 1/4 mile to a parking lot at the next exit. There I pulled the jumper and tried to start it again and it fired right up. After starting and running it for a few minuets a few times, I drove home without issue. I went out first thing this morning and it started right up.
I have no idea how to diagnose this nor how to know when it's fixed. There are a few threads here that describe a similar issue but none of them describe a resolution. I'm hoping some of you guys will be able to help.
It currently has 217k, and I've owed and maintained it for the past 7 years.
Early this year I started having a strange, very intermittent problem. While driving, RPM suddenly drop to almost nothing but the engine does not die. After a few seconds RPM comes back and the truck runs like normal again. It "feels" like it's lost fuel, then suddenly comes back. There does not appear to be any rhyme or reason to the issue, it has happened in cold weather, hot weather, freeway speeds and surface streets.
I've recently replaced the fuel sock, fuel pump(while I was in there) and fuel filter. I also tested the AFM and TPS per the FSM and they both checked out. None of these things fixed the problem.
Fast forward to Tuesday. After getting home from a 45 mile drive, I jumped back in to run a quick errand. Truck fired right up drove about 50 yards sputtered and died. Cranked it a few to and got no start. I pushed it to the side of the road cranked it again and it fired right up. At the time I talked myself into thinking this happed due to being low on fuel and being backed up on an incline (wishful thinking).
Last night, it happened again. This time in traffic on the freeway. I was able to coast it to the side of the road but this time it would not start. I started going through possible problems. Key on, CEL on solid, so EFI is good. Cracked the banjo on the fuel return line, cranked starter, no fuel. Jumpered the fuel pump, cranked starter, got fuel! I tightened up the banjo bolt and limped it a 1/4 mile to a parking lot at the next exit. There I pulled the jumper and tried to start it again and it fired right up. After starting and running it for a few minuets a few times, I drove home without issue. I went out first thing this morning and it started right up.
I have no idea how to diagnose this nor how to know when it's fixed. There are a few threads here that describe a similar issue but none of them describe a resolution. I'm hoping some of you guys will be able to help.