hot hard starter

my 75 starts right up when the engine is cold!
but it tends to idol very fast for about 1 min
and then when i step down on the accl it will idol okay.
also when the engine is hot and it shut it off
and try to start it again,
it has to turn over several times
before it will fire and run.
what do i need to do?
thanks
dave

 

What motor are you running? And what carberator?

 

Most non fuel injected engine have a fast idel when they are cold it works with the automatic choke. Starting problem when hot could be a lot of things, need more information.

 

running a 258 str six
think carb is stock!
starts great when cold.
even when 5-10 degrees out!
but when hot....not so good.
and it sputters for a few seconds
after it starts.
dave

 

I usually check the condenser first for bad hot starts (because it is easier and cheaper to do). If it isn't that then you may have some carb issues to check out. It could also be coil or other issues.

 

Make sure your choke is working.

 

will check choke
and put in new plugs
thanks
dave

 

Mine has a 304/MC2100, but my mechanic gave me this explantion for the same symptoms, and it is the best one I've heard yet:

Very small leak in the carburator. This causes a little bit of gas to leak down into the manifold/cylinders when the jeep sits. By the time the engine has cooled down the gas has evaporated, so there is no effect, but when you leave it sitting for just a short time (10-30 minutes), the gas is still there. The gas that has leaked into the engine is causing a "flooded" condition. The motor has to turn over a few times to clear the gas/fumes out of the system. The quickest cure is to floor the gas pedal and hold it. This opens up the top of the carb allowing more air in to lean it out and resolve the problem. Don't pump the pedal because this operates the accelerator pump in the carb and puts more fuel in the engine making everthing worse.

I have no idea whether this is actually what is happening, but it fits my symptoms to a "T", and the suggested solution works well.

Good luck,

JMT

 

75 258 should have the fuel return line at the fuel filter, which then returns fuel to the tank.
Some folks eliminate this and plug it off.
What can happen, it will cause a "hot soak" condition which is described by Code Red above.
After a warm engine has been shut off, the fuel remaining in the lines and/or fuel filter can/will expand; this will push fuel through the needle/seat of the carb, causing flooding.
If your fuel filter has the 3rd return outlet, make sure it's not plugged. If when taking the fuel hose clamps loose, fuel under pressure squirts out, you may have found your problem. The return nipple on the filter should be rotated to the top of the filter, above or on top of the fuel outlet; this prevents a siphon condition, which some folks say can occur.
If you don't have the return line, due to a PO or other reason, you might try rigging one up; it should help.
AMC V8s used fuel return lines as well, so this applies to them also FYI.