hard start/long crank after sitting for about ten minutes.

[kwood]

1971 ford bronco with 6cyl 200. Engine will not start after sitting about ten minutes.it will start with long crank times and finding proper throttle position. I have been adjusting timing. when set to factory setting it runs like crap and has a steady miss at 1/2 to full throttle.

 

[Thatbroncokid]

Probably heat soak in the carburetor. Fuel is getting too hot and boiling in the carb. Phenolic spacer for the carb should help lots. I had this same issue and it helped me a lot.

 

[nvrstuk]

x2 on the gas boiling out of the carb, hence the long crank time.

Try this. After you park for 10 minutes, pull the air filter off and move the throttle a few times while looking down the throat of the carb. (ENGINE OFF). You should be able to actually see the gas squirting into throat of the carb IF there is any gas left in the bowl.

IF the fuel bowl is dry, then the gas is probably boiling out. Very common on the Edelbrock 4bbl's

 

[DirtDonk]

Hey kwood, welcome to classicbroncos!
Have you had this one a long time, or is it just recently purchased? Have a history of how it runs and how long it's been since a tune-up in other words?
Any performance mods to the engine?

First thing I would do if I didn't know it's history would be to give it a full tune-up and check for vacuum leaks and how consistent the timing is.
This way you will know if you need to start going down the road of avoiding heat-soak, vapor lock, and other maladies that can sometimes plague old vehicles.

And speaking of old... If this is a new-to-you Bronco, do you know how old the gas is? Maybe you're just running on old gas, or bad gas.

Good luck.
But for sure check for vacuum leaks the next time it's running. If you're not familiar with the many techniques, sound off and we'll run 'em down for you.

Paul

 

[kwood]

Thank you for all the input. I have owned this bronco three years. recently the coil went out. I replaced it with the Pertronix coil and electronic ignition, and it also has an electric inline fuel pump.

 

[blubuckaroo]

I've had gasoline boil over into the intake manifold. There are things you can do to help keep the heat away from the carb, but the heat in the engine compartment alone is enough to cause this.
What's worse, is a six cylinder has the exhaust manifold directly under the carb.

 

[Pa PITT]

... DID IT ALL START AFTER THE ELEC PUMP WAS ADDED... BACK WHEN I HAD MY PARTS STORE . I had issues with elec pumps having too much pressure & pushing fuel over the needle & seat .... HENSE Also causing the ... LONG STARTS OR AKA SAME AS THE FUEL BOILING OVER. Find a way to check your fuel pressure.. on that old 6 cyl 3 or 4 lbs will suit it better but we found most new fuel pump put out about 6 or 7 lb's of pressure... IF YOU Can find a regulator to drop the pressure back to about 3 . go for it.

 

[MarsChariot]

Another thing that helps is to use the old technique of opening the throttle slowly to halfway. No pumping first or the problem will be made worst. Sounds like you are doing this correctly, but sometimes you need to be extra careful not to get too vigorous with moving the throttle or you still end up dumping in more fuel. This is from another vehicle, but it outlines the old carburetor method.