Cranking after driving

[Cohammer]

302 with a 2100 carb that has electric choke . After going for any short ride when I turn off engine and go back to crank it after about 10 minuates it acts like all the gas has leaked down and is hard to start . I have had 3 different carbs on it and it does it with every one . It seems to crank best if I turn it over for a few seconds and then pump the gas I am afraid it is not going to crank sometime . Any idea why it would be hard start after warming up ?

 

[piecrazy4]

What is your current ignition setup if you have a failing coil or improperly set points it can still start OK cold and be hard to start hot

 

[badmuttstang]

Could be a heat soaked carb and vaporizing the fuel as well would cause the same symptom

 

[rguest3]

Same problem with 3 different carbs? Don't blame the carbs just yet.

Try a 1/2-1" phenolic spacer between carb and intake and see if this helps.

 

[Master Chief]

Could be a heat soaked carb and vaporizing the fuel as well would cause the same symptom

Did the factory use spaces to prevent this? I run Edelbrock intake & carb. Experienced the problem of the OP, installed their spacer (http://www.summitracing.com/parts/edl-9266) and my issue went away.

 

[badmuttstang]

Did the factory use spaces to prevent this? I run Edelbrock intake & carb. Experienced the problem of the OP, installed their spacer (http://www.summitracing.com/parts/edl-9266) and my issue went away.

Yes jut not phenolic

 

[Bhall75]

I had a "77 with stock 302 and Eldebrock 4 barrel that did the same thing. I went through the electrical system (electronic ignition) and engine and never figured it out! I have a 5.0 EFI now and it is a dream... I assumed it was vapor lock but was never able to diagnose.

 

[jckkys]

Holley makes this insulating carburetor mounting gasket.

http://www.summitracing.com/parts/hly-108-52

This has both conductive and radiant heat insulating features. Heat vaporizes liquid fuel and the vapor being heavier than air, fills the intake. When you attempt to restart, open the throttle slightly and hold it there. Fresh air is needed to dilute the over rich mixture in the intake. Then cranking a second or two should allow the engine to fire up.

 

[Rustytruck]

Its normally the fuel boiling off and then condensing in the intake. When you first go to restart the condensed fuel floods the engine. Ford added a thick carb gasket with rings where the studs were so you couldn't over torque the gasket and bend the carb flange. This helped some. In the later owners manual you will read a hot start passage telling you how much to push the throttle while cranking to get the best hot start.

http://www.carburetor-parts.com/Motorcraft-2-Barrel-Flange-Gasket_p_2486.html

 

[Cohammer]

Hard start

I am running a ready to run electronic distributor set up and it does seem to help if I can figure out by pure luck how much to mash gas when starting . It has about a 3/4 spacer under carb . Maybe I go back to the manual choke and see if that helps .

 

[jckkys]

Apparently Rusty and I were writing the same reply at the same time.I find pushing the throttle about 1/4" to 1/2" to let some air in, works best after heat soak. Remember DON'T pump the accelerator after just opening it a little. Pumping pours more gas into an already flooded engine. Learning to drive carbureted engines is part of the answer to complaints many new owners have.

 

[blubuckaroo]

If you have the section of fuel line between the mechanical pump and carb too close to a heat source, the fuel trapped in there between the pump check and carb inlet valves can expand and even vaporize when the engine shuts off. That expanded fuel has to go somewhere. It usually pushes past the needle valve in the carb, overfilling the carb and flooding the motor.


X2 Rusty & jckkys,
My owners manual has instructions on starting the engine that has already been warmed up. The manual say to open the throttle slightly while cranking.
Stuff like this happens more when it's hot out.

 

[66BlueGoose]

Check your fuel / air mixture at idle, if it's running rich, heat soak will make it worse.

Ditto on jckkys cracking of the throttle when hot, just a slight depression on the gas petal an mine starts right up.

 

[Cohammer]

Sounds like the slight press of the petal is the way to go I will try that for a while .

 

[Rustytruck]

Apparently Rusty and I were writing the same reply at the same time.I find pushing the throttle about 1/4" to 1/2" to let some air in, works best after heat soak. Remember DON'T pump the accelerator after just opening it a little. Pumping pours more gas into an already flooded engine. Learning to drive carbureted engines is part of the answer to complaints many new owners have.

Yes at the same time but I type slow, proofread read slow and your to the east of me so your day starts earlier than mine. So you win but at least we agree.