Starting problems with 66 CJ5 w/YF carb

My 66 CJ5 f134 with yf carb is starting to give me a currious starting problem. Twice in the last 2 weeks after otherwise running fine, I shut it off for 10 minutes and it won't start. Smells like gas when you first start cranking but no visible signs of flooding around the carb. Spark is good at the plugs and battery is strong and new. But you can crank it forever without firing or even sputtering. Wait 20 minutes and it starts up and idles fine.

Anybody experienced this? Is it possible the carb is flooding internally and the 20 minutes gives it time to evaporate?
Eddy

 

Still looking for any ideas on this problem.

 

I would guess vapor lock. 20 minutes would be enough time for fuel to re-condense. All fuel lines are away from hot-spots?

Mark

 

I'm gonna say "hot soak" condition.
cause is engine heat.
after the engine is shut down, afterboil or engine heat increases, no coolant flow.
The cyl head absorbs this heat (along with the rest of the engine)
this heat is also absorbed by the carb
as temp increases, the fuel expands
fuel trapped in the fuel line (or fuel bowl) expands and builds pressure
it then can blow through the needle/seat inside the carb and/or overflow causing flooding or
"hot soak" condition.
check needle and seat for foreign matter, make sure it shuts off properly
check float level, or lower slightly for insurance
make sure carb has thick fiber insulator ( minimum 1/2") between carb base and head.
make sure fuel line from pump to carb is metal and away from heat sources; not pushed up/rubbing against the head or block
if all this fuel is indeed "boiled" away, it could well indeed be vapor lock

 

Thanks for all these leads. I'll check on this.
Eddy

 

Good point JP- I was not really familiar with this "condition" but it makes perfect sense.

 

Jim,
I think you're right about needing that 1/2" gasket as a heat insulator, mine only has a paper thin one and eveything else checks out ok. Where would you go to find one that thick?

Eddy

 

try Napa or local parts house
probably won't find it under vehicle application though
need to browse thru their carb base insualtors and gaskets
and match it to yours, bolt pattern wise