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302 dying at warm highway speeds

I have a 1978 F150 with a 302. I replaced the starter and battery. My problem is when the truck warms up, and I'm going moderate speed (50 mph), the engine sputters, jumps, and then dies. I will take anywhere from 10 to 20 minutes to get it to turn on. Please help so I don't drop tons of money into stuff I won't need.

Thanks
 

DNFXDLI

The Token Canadian
Staff member
When it dies, check to see if you are getting fuel by looking down the carb and pulling on the throttle linkage...it could be the module like the other guys said but you might be having a fuel delivery problem as well.

I had a 78 Bronco that did this and it was fuel.
 

jebadiah04

Rooster Snorkler
849
27
Definitely make sure when it dies that the accelerator pump is squirting fuel. My k5 did that. Took me a while.to figure out.

Next thing I'd check is the ignition module then coil. Just take them off and run into oriellies or such and they will test for free. Make them test a few times so they warm up since it's failing when warm
 

Beach66Bum

Moderator
Top Poster Of Month
Here's a pic
image357.jpg
 
Last edited:

jebadiah04

Rooster Snorkler
849
27
Me no see pic
 

DNFXDLI

The Token Canadian
Staff member
Here Roy:

image357.jpg
 

Big Jim F150

73-79 Ford Trucks Rock
Besides your coil and Duraspark II control module, also check your distributor, to see if your pickup wheel is going bad, or is bad I had that problem with the pickup wheel in my distributor on my 78 F-150 Ranger Lariat Trailer Special with a 351M / 400 engine. Check that out, also the Duraspark II control module can go bad, but when they go bad the truck won't start at all. I had learned that on a 77 F-350 Custom with a 351M engine. When it would crank and wouldn't start I knew it was that control box, and they're not all that expensive about 25 - 30 dollars for one, and they're not that hard to change out, also check your connections, and make sure they're clean and tight. For a bad connection can cause your problems also. Hopefully you find this rather helpfulsmilieFordlogo smilieFordlogo
 

Fellro

Moderator
Staff member
I had a ignition module play games on a 79 Mustang I had, be cruising just fine, then out of the blue just die. Give it a bit of time, fire right up like nothing was wrong and go for a while again. Definitely need to verify it has fuel when it does die though, as the cap could possibly be not letting air in, and then build a vacuum in the tank.
 
You have received all the right suggestions. But as it is intermittent, you will have to do a diagnosis when the problem exists. First determine if it is fuel or spark. As was suggested, when it happens, look in the throat of the carburetor and move the throttle. If you see fuel squirt, then the problem probably is spark. It sounds like it could be temperature related. For fuel problems look for fuel pump, tank venting, vapor lock, cracked fuel lines, or congested filters. On the spark side look for coil, distributor, broken or badly connected primary wires, or the most likely, the control module. Mine once quit out in the AZ desert. Fortunately I had a spare. If you're running a semi-conductor controlled ignition system ALWAYS CARRY A SPARE. Try to do a good diagnosis instead of just changing parts. In the long run it will save you money. :wavey:
 

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