Weird idling issue... carb or electrical system?

[Ollie88]

Hey guys,

So I went out for some light off-roading with my '78 FJ40 this afternoon, everything seemed fine until the engine suddenly died. When trying to fire it back up, I turned the key but nothing happened (the starter was n around). So when I opened the hood it turned out that the aftermarket power-steering system had gotten quite hot (I was driving in 1st and 2nd gear going up a steep hill with lots of curvy turns), it had built up so much pressure that it was spitting out oil over the battery and a few other wires.

I then let it cool down, cleaned up the power steering oil and it fired right up again so I continued my trip. But after a couple of minutes the engine shut down again, time after time. I couldn't keep it running idle within keeping my foot on the gas. I check the idle screw / idle speed, turned the screw all the way in but no difference. I was able to drive it home in the end as highways in higher gear were not an issue, but it wouldn't idle.

When I came home it would suddenly run idle again...! for about 1-2min and then without touching the gas the engine just died right when I tried opening the hood again.
So I'm really confused now, is this a carb problem or do you think it has anything to do with the electrical system as well?

I would assume that even though something short-circuited it would either just run or not run at all, but if it;s the carb: how can it suddenly not run idle anymore? Think this can't be a timing or carb setting issue since I can't believe the settings would change without touching it? Also hard to believe it is the intake gasket as it would surprisingly run idle again when I came home....but then died after 1-2min

Would appreciate any input where I should look!

 

[Ollie88]

Been searching the forum already and wondering whether it could be the idle solenoid? Could it be that it has gone bad due to a short-circuit?

It's weird but I've also seen some sparks coming off the fuse holder board left from the driving seat...

 

[JohnnyC]

If you thinking it’s the fuel cutoff solenoid is being shorted someplace … unplug it put 12v to it and ground the other (it’s been awhile I think there’s two wires to it) then see if it still does it

When it dies what is your fuel level like?

 

[Ollie88]

Hey guys, so the problem persists:

- runs well for the first 20min, then when the engine has warmed up well it won’t idle anymore
- fuel cutoff solenoid is working, I did see the o-ring has a small crack and might be leaking (could that cause an issue?)
- choke pulled has no effect, not when cold nor when it’s warm
- idle screw works, I have turned it all the way in but barely idles when warm (when it’s cold it idles high) and engine dies all the time when eg stopping for a light

Anyone knows what the issue could be?

 

[Ollie88]

Well, it’s fixed! My mechanic had replaced the ignition rotor, all spark plugs, the ignition coil and 2 of the 3 fuel filters but the problem remained exactly the same. It just wouldn’t idle, engine would die all the time when slowing down for a light and ran very rough.

I then took of air filter, sprayed a whole of carb cleaner to check for vacuum leaks (no leak) and took off the fuel shut off valve and also sprayed carb cleaner into the idle circuit. I think the little o-ring might have gotten stuck somewhere since it didn’t come out when I removed the cut off valve/solenoid.

I then also replaced the 3rd fuel filter in between the 2 seats and the engine ran like never before! Perfect idling

Thanks anyway guys, problem solved!