Stumbling, Sputtering Issue FJ60

[akunes]

FJ60 Noob here. After reading through countless threads on the stumbling, sputtering issue, I'm quite honestly overwhelmed.

My LC is an 86. It was garage kept and barely run the last 10 years. 173k miles. The carb was just rebuilt.

It's been running like a dream the last 3 weeks. Yesterday out of the blue, it started hesitating and stumbling in 3rd and 4th gear on flat while throttling.

I took it to a local mechanic today and had them give it the once-over. They drove it and couldn't replicate the sputtering. Based on their report:

-low transmission fluid
-missing breather from valve cover to air cleaner
-hose at water outlet kinked
-P/S hoses, lines: seeping a little
-Clutch fluid level - a bit dirty

They didn't do any work outside of mentioning the above.

Appeared to be riding great and 20minutes into my drive home, it nearly stalled out driving up a hill. The mechanic did say for an extra $140, they'll do an engine diagnostics check if it happens again.

Any recommendations on next steps? I don't want to run up a tab at numerous mechanics telling me they can't replicate the problem. I'd like to do the work myself, but truly have no idea what to do here.

Any recs would be greatly appreciated.

I noticed a disconnected wire here: (not sure if that has to do with anything)

 

[OSS]

It's very likely (I'm thinking 100%) a fuel delivery issue. The engine is intermittently getting starved of fuel.

Although the carb was rebuilt, the process of removing the fuel line and replacing it could have dislodged crud in the line to end up in the carb. Again.-intermittently blocking the main jet.

I would :

1. Drain the gas tank to make sure it's not full of crud.
2. Blow out the fuel line from the engine compartment fuel pipe back to the tank with low pressure air and fuel cap off.
3. Replace the fuel filter regardless.
4. Replace the fuel pump if its 10 years old or older
5. Try again.

If it's still hesitating under load, there's likely crap in the carb.

 

[Seth S]

Even before you drain the gas tank I’d try replacing the fuel filter and cutting open the old one to look at the element. You could also try a redneck rebuild on the carb to see if that clears out the issue.

Question: when the stumbling happens can you accelerate out of it? Meaning can you go heavy or light on the pedal and get away from the hesitation?

 

[akunes]

It's very likely (I'm thinking 100%) a fuel delivery issue. The engine is intermittently getting starved of fuel.

Although the carb was rebuilt, the process of removing the fuel line and replacing it could have dislodged crud in the line to end up in the carb. Again.-intermittently blocking the main jet.

I would :

1. Drain the gas tank to make sure it's not full of crud.
2. Blow out the fuel line from the engine compartment fuel pipe back to the tank with low pressure air and fuel cap off.
3. Replace the fuel filter regardless.
4. Replace the fuel pump if its 10 years old or older
5. Try again.

If it's still hesitating under load, there's likely crap in the carb.

Much appreciated!

 

[akunes]

Even before you drain the gas tank I’d try replacing the fuel filter and cutting open the old one to look at the element. You could also try a redneck rebuild on the carb to see if that clears out the issue.

Question: when the stumbling happens can you accelerate out of it? Meaning can you go heavy or light on the pedal and get away from the hesitation?

Thanks. I can't accelerate out of it. It just wants to die if I continue to stay on the pedal.

 

[akunes]

Even before you drain the gas tank I’d try replacing the fuel filter and cutting open the old one to look at the element. You could also try a redneck rebuild on the carb to see if that clears out the issue.

Question: when the stumbling happens can you accelerate out of it? Meaning can you go heavy or light on the pedal and get away from the hesitation?

Swapped out the fuel filter yesterday. The old one seem pretty gunked up. Drove fine yesterday. Hopefully that was it. Thanks.

 

[Seth S]

consider picking up a few extra filters in case they clog up quickly. If they do then would be good to drain the fuel tank and flush the lines as @OSS recommended.

 

[g-man]

white wire for carb cooling fan?

 

[morganism]

Is it idling rough? if so, check EGR stuck open.