My son's '81 D150 /6, 727 A/T started chugging and stalling during short (10 minute) rides. We thought it might be a cooling problem, got hot, but it's not spilling into reservoir. He was able to get it started and then drove about a block and a 1/2 in reverse to get to a save spot. Wouldn't go anywhere in drive. Happened a 2nd time when I "tested" it while hot and same thing happened to me. I'm thinking it's vapor lock. Fuel line goes over the valve cover and does get a bit hot. Poured a little gas into the carb to get it started and home.

We then played with the choke and mixture on the carb and reset the timing. Air filter was changed, checked the fuel filter and no clogs. Plugs are all clean and properly gapped and dry. Oh, and there's also an electric fuel pump running as well. Still mystifying. We did clip a few wooden clothespins on the metal fuel line to dissipate the heat and it seams to be running ok now, Test drive at night, and then an 11 mile trip in stop adn go in 95 degreee heat. What are we missing as far as a diagnostic problem? It's good for now, but what's causing the chug-chug-chug and no gas problem.

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'74 Duster
'74 Valiant

just a few questions:
Are you sure you have fuel to the carb when the problem happens?
Do you have a 1bbl?
Did this just start happening when it got hot out?

It sounds like it could be vapor lock if you have a good fuel supply.
I would reroute the fuel line to the front of the engine and get one of those thick gaskets for the carburetor to manifold.

good luck!

Wooden clothespins do not dissipate heat, that is an old wive's tale.
Best fuel line material and routing is per the Fuel line mod. Metal pump-to-carb lines tend to transmit a lot of heat to the fuel.

Have one fuel pump, not two. An electric one isn't needed, just a properly-working mechanical one, and if there's trouble with an electric pump upstream of the mechanical one, it'll restrict fuel to the mechanical pump and create vapor lock for you.

The carb gasket must be the 3/8" thick variety.

And...the carb must be in good condition!

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