STRUGGLING!! Fuel Delivery Problem....'54 DeSoto Flat 6

[BloodyKnuckles]

Sooooooo.....I've been struggling with a fuel delivery issue for years with my wife's '54 DeSoto flat 6 251. It has another new mechanical fuel pump (..5th one), rebuilt 1 barrel Carter Ball&Ball (..rebuilt 3 times), all new 5/16 steel line from the tank forward, super clean tank and a heat shield on the fuel pump.

Here is the symptom. During the warm months it will run fine while driving but if it sits idling or is shut off and sits it will not run. It will have to cool almost completely before it will start and run.

I have worked the accelerator pump during this time and no squirt. I have pulled the top carb horn and found the bowl to be dry. I have pulled the line from the pump to the carb and it is dry but the fuel bowl is full. The fuel lines are as far from a heat source as possible yet they are very hot.

I am getting gas to the pump but for some reason, when hot, it won't make it to the carb.

None of this problem is evident in the cooler months.

I would rather run a mechanical fuel pump but would it be best to run a really good electric pump?

Now, for a side note, my '51 Plymouth has a flat 6 with a mechanical fuel pump and 3 carbs and for 7 years never this issue.

Any input would be very much appreciated.

BloodyKnuckles

[claybill]

i have fuel problems too. and only in one of my 3 cars.!

i found that there might be toooo much fuel in the manifold, so i hold the accelerator flat to the floor, no pumping, and it usually starts. this allows the max amount of air thru the carb without the squirt of the pump.

vapor lock...clothespins...?????????? i doubt it.

after sitting for a few months the slow turning 6v starter wouldnt encourage the fuel pump to pull fuel...so i primed the carb and it started right up....so i installed a new pump and it pumps easily . i checked it.

I had idle/stalling problems while driving one night and had to drive home with the dash throttle open 1/2 way to keep it from dying out. next day i completely cleaned the carb..seems better now, starts in a snap. we will see... in this case i assume that there was some crud clogging up the jets....

and i have another problem next thread.

bill

[captden29]

Bloody, i had the same issue on my 54 windsor. i moved the fuel line from the pump to the carb as far from the exhaust manifold as i could. that solved it. i have the fuel filter at the carb with the glass bowl and you could see the fuel bubbling in there. it is all about the engine heat. when the engine runs cooler there is no problem. i got a tubing bender and some new line and bent it in some crazy ways so it is as far from the hot engine as possible. capt den

[55 Fargo]

Bloody, i had the same issue on my 54 windsor. i moved the fuel line from the pump to the carb as far from the exhaust manifold as i could. that solved it. i have the fuel filter at the carb with the glass bowl and you could see the fuel bubbling in there. it is all about the engine heat. when the engine runs cooler there is no problem. i got a tubing bender and some new line and bent it in some crazy ways so it is as far from the hot engine as possible. capt den

I have noticed the same thing Capan, would somefuel line insulation do the trick, rather than moving the fuel line away?

I have my fuel lines a good distance away fromthe manifolds, but maybe not enough....

[meadowbrook]

My D34 sometimes suffers from this. I think it could also be the fuel boiling within the carb. As you know it sits on the intake and that is on top of the exhaust manifold. It could be your heat riser flapper may stay open even after warmup and allow some exhaust to warm the area below the carb too much.

Maybe this heat transfers into the carb and you get the fuel in the float chamber boiling away. Lots of folks in this forum have mentioned this possibility and I was initially skeptical (sorry ), but it makes sense.

I once actually saw fuel leaking out of the carb after a hot run, like it was boiling and being spit out.

I plan on checking the riser position when the car is hot to see if it is solidly on the closed position or if it can move back to the open position. Maybe the spring needs to be repositioned.

[TodFitch]

Is there an insulator (non-metallic) between your intake manifold and the carburetor? If not, should there be one that is missing?

[claybill]

the bottom carb gasket is usually the fiber thick on....right.?

[38plymouth]

I had the same issue one summer. I put my heat shield back on and moved the line as far away as possible from the manifold. I also added a plastic see thru fuel filter between the pump and carb. It's never happened to me since.

[BloodyKnuckles]

Just to keep you guys up to speed

I do have a phenolic spacer under the carb. I have relocated the fuel line from the intake. I really thought of building a shield of some kind for the fuel line. I have also tried a heat sleeve over the line.

I picked up a very good electrical fuel pump that I need to try.

I'm going to install it now.

We'll try that for now.

Thanks guys.

BloodyKnuckles

[54Illinois]

Good luck, I would like to hear the results as well!

[claybill]

hi bloodyk....tell me more about the electric fuel pump? source, cost, type.??

bill northern ill.

[Cpt.Fred]

hey bloodyknuckles,

i'm running electrical on mine and re-routed the fuel line to avoid engine heat.

instead of going all the way around the front end,

i let it run up the driver's side a-pillar and then all across the firewall.

when i installed the tube headers i was too scared of the heat there to use the normal way.

but it's still strange, and i think you might have done everything already...

so, good luck with the e-pump. try and let it run against the float bowl valve

with open carbs, to check if it can hold back the pressure! i'm running 0.3 bar

on mine without needing a flowback line.

strange enough i'm also having engine trouble here, most likely fuel as well, but that's a different story...

so, good luck and take care!

Fred

[austinsailor]

Two things you can try to make sure fuel is the issue. Octane booster, like you would use for a hot rod, will also boost the boiling temp of the gas. This works in my 48 B1B that has the same problem. My 40 Dodge sedan has only had this problem once, at the end of a parade in high 90's heat.

The other is av gas from the airport. It has a much higher boiling point. Cost more, but will solve your problem.

Electric fuel pump will do it, or a squeeze bulb from an outboard will get you going by refilling the line and carb.

[claybill]

good idea...i'll try the octane booster, the head for my 'test hill'..

bill

[BloodyKnuckles]

What I have done was installed an electrical fuel pump at the tank and vintage pressure regulator before the carb. I am running through the mechanical pump. So far so good.

I had the fuse for the pump blow and sure enough the problem came back. I really think the isssue is a worn cam lobe.

Thanks for the help guys.

BloodyKnuckles