Irratic idle when hot after sitting...

[REZARF]

Howdy-

Just returned from three weeks away from my cruiser (don't know if that is part of this or not).

We are having 95 degree days here in Denver, I drove my cruiser yesterday for about 10 miles (it ran fine) and after I tried to restart it, I was running it was idling at around 400 to 800 rpm really rough, if I drove it on the road, it smooths out without hesitation.

This is only happening right when I start it up after driving it for a while.

Any suggestions?

Thanks, I swear this board has kept my cruiser on the road more than any other source of info.

Rezarf <><

 

[spotcruiser]

Stock exhaust manifold? Do you have a carb cooling fan that works? My stock '78 will do as you mention when the cooling fan is not working. The heat from the exhaust manifold, via the intake manifold, appears to cause boiling at the carb and erratic operation. It was especially bad when the truck had the California "thermal reactor" exhaust manifold, which retained more heat (replaced it with a Federal exhaust manifold when the reactor gave up the ghost).

Never have that problem with my '76 that has headers (no physical contact between the base of the intake manifold and the exhaust manifold, as in a stock rig).

 

[REZARF]

Thanks for the response,

I have headers but I don't have a carb fan. I was thinking a vacuum leak, but then I think I would always have the rough idle.

Any thoughts?

Rezarf <><

 

[Pin_Head]

I agree that is sounds like the carb is overheating and the fuel boiling. The reason that this doesn't happen when the engine is running is the air flow through the carb cools it.

 

[2badfjs]

vapor lock and HOT! HOT! HOT!

WELCOME BACK DREW!!!!

 

[REZARF]

Thanks Jim, good to be back. We should begin talking sliders again

Can a carb fan be retro-fitted to a stock 76? What is involved?

Thanks again for the help.

Rezarf <><

 

[DSRTRDR]

maybe send it to Mark Algazy or Jim Chenoweth?

 

[bsevans]

Thanks Jim, good to be back. We should begin talking sliders again

Can a carb fan be retro-fitted to a stock 76? What is involved?

Thanks again for the help.

Rezarf <><

Does a 76 have louvers on the driver side panel? If it does, then you can mount a factory fan. You would need the thermocouple and bracket that the circuit board uses to turn the fan on and off. You could make your own control using a type K thermocouple and a circuit from Omega that converts the thermocouple output to an on/off state to control a relay. And, yes, it sounds like vapor lock, which was enough of an issue on earlier FJs that Toyota added the carburetor fan and control system. My vehicle would have a very hard time starting after running it hear in southern AZ and then parking. I fixed the fan circuit and have had no problems since (over 15 years)

 

[Rick '79 FJ40]

Does a 76 have louvers on the driver side panel? If it does, then you can mount a factory fan. You would need the thermocouple and bracket that the circuit board uses to turn the fan on and off. You could make your own control using a type K thermocouple and a circuit from Omega that converts the thermocouple output to an on/off state to control a relay. And, yes, it sounds like vapor lock, which was enough of an issue on earlier FJs that Toyota added the carburetor fan and control system. My vehicle would have a very hard time starting after running it hear in southern AZ and then parking. I fixed the fan circuit and have had no problems since (over 15 years)

I don't mean to hijack this thread, but I have been wanting to get my carb fan working, too. My rig had headers when I bought it, but the fan and control unit are still there. I think I just need the thermocouple. Is there any info around on how to hook one back up after installing headers? I'm not 100% sure the control unit works. I unhooked it when I forst got the truck because it seemed to be draining the battery. I may just need to replace it with the Omega unit.

I would appreciate any help you guys can give me.