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My WC56, T-214 engine has got me scratching my head and I would appreciate some advice on how to fix it. It starts no problem and burns clean. At low temperatures it idles no problem. When it has fully warmed up it keeps cutting out and will not idle?

First thing to check is that the choke is fully open
After that it could be the condenser or coil

Ernie has good advice...
To rule out the coil, see if the coil is hot when this is happening. Put an ice pack on the coil to cool it down and see if the problem clears up.

I would replace the condenser anyways. They are cheap.....

Guys, many thanks for the advice, much appreciated. Will give it a try!

.... and you do have the original heat shield mounted above the fuel pump, between it and the exhaust manifold, of course?

I have changed the condenser and points (while I had it all out), the coil is running warm but not hot. I will get another condenser to rule that out. The choke seems to be functioning normally but how would I double check this without opening it up? Something that could support the choke not functioning 100% is the smell when it is hot, it smells like there is unburnt fuel coming out of the exhaust.
I have checked and there is no guard between the fuel pump and exhaust manifold. Could someone please steer me to a picture of one? So this would be preheating the fuel which would cause it to not combust properly?
Thanks again for the views and suggestions, much appreciated.

Here is what the heat shield looks like. It is similar to the one (D) in the picture below. This one is on an M37:

Thanks for the picture, have double checked and do not have this between exhaust manifold and fuel pump. I will get one and fit it. I would never have guessed this in a million years, why would warm fuel cause the engine to no idle when hot?
Thanks again,
Max

Max

It seems you are getting problems when the engine is "warm" which should not affect the fuel under normal circumstances. If you get the problem when the engine is "hot" (does not need to be boiling) say sitting after a long run, climbing hills or driving slowly in a parade on a hot day it could well be vaporisation of the fuel.

That shield is very important in these circumstances as the radiated heat from the manifold will raise the pump temperature to a point where the fuel turns to gas. Once that happens the pump will "wheel-spin" as it is designed to pump liquid not gas. So you now have bubbles coming through in such quantity the actual fuel flow is insufficient to keep the float level at the right height on a running engine.

The shape of the shield is important as it does two jobs. It stops radiated heat and redirects airflow from the fan across the pump.

Quick permanent fix for any vaporization problems - buy a $20 electric fuel pump and put it in line near the tank. Also saves the battery after a long period in the garage by filling the carburetor before you engage the starter instead of relying on the mechanical pump to use up 15 cranks to get the fuel up - or having to open the engine bay and hand pump if you have a lever model pump on your vehicle.

Lang

Lang,
When the engine is cold or warm it idles no problem. It is as you say after an extended run that the problem occurs. It still runs at higher revs but cuts out at idle. The engine is not boiling but running at its max temp. I will look to put the heat shield on for now and consider the electric fuel pump for a later date. Will let you know how I get on. Would never have guessed this.

Many thanks,

Max

As I understand it the primary problem is when the engine is hot and the truck is stationary, or moving very slowly, such as in a parade. The fuel moves slowly though the system and vaporises, or part vaporises in the fuel line and fuel pump, so the pump just can't do it's job.

Standard equipment on these trucks was minimum of a fuel pump heat shield, late trucks had a radiator shroud that aided cooling ( plus airflow past the pump ) and I have seen people insulate the fuel line past the block and up to the carburettor too. Obviously modern shiny metallic plastic coated insulation would look hideous, but I'm sure you could fined suitable fuel line insulation that would look appropriate.

Finally a good flush of the radiator, preferably when outside the truck and upside down, would always be good for the cooling system generally.

Thanks Gordon, would never have guessed this in a million years, great to have access to such a wealth of experience.

Max

As Gordon says, at higher speeds there is greater fuel flow and the fuel does not have as much time to sit in the pump to turn to gas. The pump is also moving much faster with the higher revs so if it is vapourising even say, 50% efficiency, over a cold situation is enough to keep up with the engine.

Insulating the fuel line after the pump is a waste of time. If the pump is still cool enough to be working but vapourisation is happening in this upper section of line there is still the required fuel going into the carburetor. The bubbles will just vent to air (and normally reliquify because the carburetor is cooler) and the needle will ignore the gas and remain open to allow the solid fuel to flow. The pump is everything!

If you have a very hot engine sitting switched off - the Ford V8 was bad for this - the carburetor can get so hot the fuel in the bowl vaporises and the float level drops making starting hard. If the pump is cool enough it will fill the bowl in a couple of turns and all will be well. If the carburetor got hot in the Ford the stupid position of the pump will guarantee that also will get hot so you are stuffed. Luckily the old Dodge is not nearly so susceptible with the pump lower down not subject to rising heat, not having to lift so high and having a shield to protect from the radiation.

As I said get an electric pump and everything can vaporise to its hearts content but the fuel will just keep coming.

Lang