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1950 Plymouth special deluxe not starting when hot


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Hello my 1950 special deluxe is not starting for a while after it’s hot it starts after cooling down.

If I move the timing then it starts even when hot but the car runs hard and engine is racing but it doesn’t get to shifting speeds. I will appreciate any input on what to do If anyone has had this experience

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Engines need three things to run








Which is missing?


We can't tell you that, only you can tell us.


Once you sort out which is missing then, maybe, we can help you find the issue.

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I had the same symptoms.  It turned out the coil was slowly failing.  Plus, a bit of vapor lock - I changed coil and wrapped fuel line that runs near the manifolds with insulation designed for fuel lines.  Problem solved.

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I had a similar issue but always thought it was the ethanol crap gas.


I took off my carb and found out hat there was a 1/4 pool of gass sitting i the top of the intake manifold.


When I took the air horn off the carb I discovered that the issue was the float. It had developed a home in the brass float and I could hear gas inside the float. The gas was then making the float sink and cause extra gas to flood out the carb and made it so hard to start.  I put in a NOS brass float and now the car starts right up even when hot after driving it and then getting back in for a restart.


A very small issue that caused my hot starting pbm.  Just took sometime to figure what to look for to diagnose the pbm.


Rich hartung


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It’s not uncommon to have this problem. The ethanol gas boils at a lower temperature than the old gas did so it’s essentially boiling out of the carb. Many of us have added an auxiliary electric fuel pump that can be used to push gas through the carb to combat the problem.

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From experience,  my engine had the same symptom.  Many people will tell you it's vapor lock.  It's more likely to be perculation.  These engines are 700 pound heat sinks. After sitting under hood Temps raise with radiators and engines both contributing heat to the situation.   Fuel in the float bowl boils and over flows causing a flooded engine.  When thus happens try a wide open throttle start.  Slowly press the gas pedal to the floor and hold before engaging the starter.  If it starts but blows black smoke for a few seconds, this confirms raw fuel in the intake.  You can correct the majority of this symptom by lowering the float a couple 32ths under factory spec.  This will help give the fuel in the bowl some room to expand into.  I recall some late 70s Datsun models had a amall fan from the factory that blew air toward the carb float bowl.  Guess it was their way od dealing with a similar problem.


Edited by greg g
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I illustrated the fuel boiling theory in a YT video I made. I was convinced that winter fuel boils at a lower temp. I am not a chemical engineer, I cannot prove it. A hot spring day, with winter fuel at the pumps still, or left in your fuel tank, add a heat-sink hot engine. Then turn it off for 10 mins. Try and restart it.  You’ll likely experience what I found. While parked, raw fuel was percolating out the idle jet just below the throttle valve. Sitting and pooling in the intake manifold. 

Yes another guess.  It is fun to participate in these threads and share our experiences. 

Honestly I’d be inclined to throw a new $15 6V coil at it.  Rock auto. They’ve worked very well for me. 

Edited by keithb7
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Everything mentioned, thus far, is a possible culprit. Most usual, that comes to mind, is gas boiling over into the intake. Had that myself; using non-ethanol helps a bit. It still does it, but just not so much :)

Easy to check, warm-up the car, shut it off, wait 10 minutes, take off the filter - do you see\hear gas leaking into the intake? That's it.


However, as mentioned, it could be anything... More information needed here.

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This is a topic hit on every summer. Even with new electric fuel pumper Booger can experience the same hot car no start issue....Corn gas does not touch Boogers lips..

and when a coil STB it stops (to my understanding) .I like Keiths 2 cents and try a new/hot coil. Hell for $15 youll have a back up

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