Carb fan fixes

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On the trail, noticing my rig is "dieseling" when I shut it off and no carb fan kicking on---what are best things to check first?

TIA
 

Gretsch

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What engine? 2F? De-smogged or factory? Assuming 2F, I would check the Emissions Control Computer. It controls both the carb fan operation and the Idle Control Solenoid, which cuts off fuel flow to the carb after shut off (among other things) thus preventing the "dieseling" you speak of OP. Sometimes the solder joints to the wiring harness on the EC wear out and no longer make connection. Maybe the harness plug came off (unlikely). Or the EC could just be shot. Does it idle OK? All guesswork without some deets on your truck. HTH.
 

OSS

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The emissions manual is your friend

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Before we go down a rabbit hole that you will find to be deep and twisty…what is the current state of your engine. Is it likely that it hasn’t seen any real maintenance in the past 30 years beyond the basics like oil changes, filters, and ignition components? Or have you meticulously maintained everything and done all new gaskets and hoses and seals on a regular basis? Is the carb the original and has it ever been rebuilt?
 

Spike Strip

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Easiest thing to check first: The wire coming from the fan to the thermo-switch under the rear of the intake is a ground. Check the wire first to see if it's intact and still connected to the switch. If yes (or even no) and the green connector is still there, or not, with key on engine off, ground that wire and see if the fan runs. If it runs, then it's the switch or wire. If not, then possibly fan or something in the fan circuit. Apply 12v directly to fan to check.

Smogged? Desmogged?
 
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It is a stock 2F, still has factory smog. Think everything was refreshed and dialed in about 12 years ago, seems like yesterday.

I'll look at the items you all suggested., thanks!!
 
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BATTLECRUISER OPERATIONAL

Thanks to all, also @mongoose2231 for literally saying look for burnt out carb fan wire hanging there... found carb fan wire hanging beneath Cruiser (view from below, looking up).
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Based on some mud posts decided to just ground to frame (hack I guess, but I will chock it up as a win).
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Worked well ---sweet, cool air, aaah! Glad those ornamental fender vents are good for something other than looking pretty. One Vodka Tonic difficulty level.

Had to wait for the carb fan to turn off - took more than 20min, less than 30 -- during waiting +3 Vodka Tonic

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Spike Strip

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I put a piece of oven-wire insulation over the section that near the manifold to prevent from happening again. But Vodka Tonic kinda makes one flame-proof, too.

Cheers
 

ToyotaMatt

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I put a piece of oven-wire insulation over the section that near the manifold to prevent from happening again. But Vodka Tonic kinda makes one flame-proof, too.

Cheers


i personally craft these the traditional TOYOTA way by hand with pride ,,,,,,,,,, :cool:



oven wire insulation ....:rolleyes:


do we need to have another " that talk " again Alf 🤔



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I’ll be a little surprised if the carb fan fixes a dieseling problem.
 
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I’ll be a little surprised if the carb fan fixes a dieseling problem.
I’ll expand my thought process for the OP. The carb fan is ultimately needed to help cool the carb after shutdown and reduce or eliminate vapor lock…where fuel basically gasifies in the lines. So dieseling occurs before the carb fan ever turns on usually….if the carb fan does run 🤔 while the engine is running then it might help. Usually though dieseling is a result of small leaks inside the carb or carbon buildup in the combustion chamber. Or a fuel shutoff that’s not shutting off. So the truck keeps running after the spark is removed.
 
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Thanks for the detail. I won't be able to test drive until the weekend, so have to wait to see how it behaves.
 

Gretsch

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Or a fuel shutoff that’s not shutting off.

This was my suspicion. I understood the carb fan to be controlled via relay through the EC and since the ICS is controlled as well by the EC thought maybe there was a correlation for both issues in the EC. Obviously it was much easier than that with a busted wire so good there. Guess the dieseling was just coincidental based on what OP was doing with the truck at the time. But would appreciate any clarification on the carb fan control. Does that sound correct? Asking for a friend. :)
 
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This was my suspicion. I understood the carb fan to be controlled via relay through the EC and since the ICS is controlled as well by the EC thought maybe there was a correlation for both issues in the EC. Obviously it was much easier than that with a busted wire so good there. Guess the dieseling was just coincidental based on what OP was doing with the truck at the time. But would appreciate any clarification on the carb fan control. Does that sound correct? Asking for a friend. :)
Sounds correct. I don’t know if the carb fan will turn on when engine is running or if it’s engine off only? I haven’t done any googling or diagram reviewing to answer this for myself yet.
 

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