Fuel boiling at fuel pump
 

I drove my 47 tudor today on the first really hot day of the year. Outside temperature was 90. My engine temp never got above 180. I experienced vapor lock so severe my electric pump would not clear it out. When I opened the hood I could hear gas sizzling, popping and bubbles in the sediment bowl. I run a phenolic spacer on the carburetor. I believe the vapor lock to be at the pump. 89 octane pump gas. What do I do about this problem?

Re: Fuel boiling at fuel pump
 

I had the same issue till I installed a adjustable electric fuel pump , Made adjustments till I was able to achieve enough pressure to overcome vapor locking .
Vic

Re: Fuel boiling at fuel pump
 

My fuel line used to run along the chassis adjacent to the exhaust - fuel came out near boiling at the pump. Line now runs along the driveshaft tunnel - problem solved

Re: Fuel boiling at fuel pump
 

The car and engine is all stock except dual exhaust. I'll insulate the fuel line from the tank to mechanical pump and see if this helps.

Re: Fuel boiling at fuel pump
 

Seth, with my '47, the issues is with the fuel line from the pump to the carb. I put a piece of heat shield insulation on the line....the ends heat shrink to hold it in place and am "testing" the process now. Like you, the engine temp never went over 150*, but I could not hold my hand on the fuel line!! My electric pump was able to push through the block, however.

Good luck...Dick.

Re: Fuel boiling at fuel pump
 

Was there any corn in that fuel?

Re: Fuel boiling at fuel pump
 

Yes the typical 10% blend 87 octane.

Re: Fuel boiling at fuel pump
 

Hi Seth, No help here sadly. Any time I've had the issue I used cold rags applied to FP and lines under hood, combined with waiting.

I hope I don't take this off track here. But I'm curious under what conditions the '47 quit running? Were you driving at the time, or had you stopped and turned it off, and the issue happened when restarting?

Re: Fuel boiling at fuel pump
 

Seth, I have the same issue on my 35 fordor when ambient temperature is in the 90-100° range, and my car stops moving. I'm using a '47-'48 glass bowl fuel pump, and the glass bowl is located very close to the left side head and intake deck. This area seems to be out of the normal airflow, and more prone to being in a heat pocket. At times I can see the alcohol boiling/bubbling inside the glass bowl. This causes a pressure buildup in the gas line, most likely both to and from the fuel pump, which stops the gas flow. I can overcome this quickly by placing a rag soaked in ice water directly on top of the fuel pump and the gas lines coming into and out of the fuel pump. 2-3 minutes of this and the engine will restart and I'm on my way. One thought I had to overcome this problem would be to make a 1" aluminum spacer, that would locate between the pump and intake manifold, and change to the longer FP rod. This would bring the fuel pump bowl 1" higher from the heated engine, and possibly more inline with the air flow. In addition, maybe add a heat shield between the bowl and engine, or come up with some method to direct cooler air on the fuel pump and glass bowl. Some of these ideas came from G.M./George Mitchell's experimentation and testing done several years ago.

Re: Fuel boiling at fuel pump
 

Vic: Could you help us ALL out, and publish the make and model of the "adjustable fuel pump". We are all entering the same time of year that "vapor lock" seems to be prevalent. Thanks

Re: Fuel boiling at fuel pump
 

An old trick - though not exactly permanent - was to put a wooden clothes pin on the fuel line, as it, in theory, sucks some of the heat out of the fuel and allows for it to remain somewhat cooler.
Not exactly permanent, but not entirely bogus, either. But it IS just about the cheapest fix you'll find! ;)

Re: Fuel boiling at fuel pump
 

I siphoned the ethanol blend from my tank and put non-ethanol in, I am lucky to have two stations that sell non-ethanol within two miles of me.

Re: Fuel boiling at fuel pump
 

Seth
Install an electric pump inline near the tank. Make up a return line to the tank with a pressure regulator from a tee between the mech. pump and carb. The recycling fuel will be less prone to boil.
None of this is original or stock, but may work.
Bruce

Re: Fuel boiling at fuel pump
 

Old wives tale.

Re: Fuel boiling at fuel pump
 

My old wife said the clothes pin worked because it altered the airflow pattern and created a alternating low and high pressure system vortex that brought in an arctic air mass from the north and kept the fuel line cool.
You tell her she's wrong....I dare ya!

Re: Fuel boiling at fuel pump
 

Does Illinois even sell gas without corn???

Re: Fuel boiling at fuel pump
 

Does Illinois even sell gas without corn??

Don't know, but you can buy corn without the gas.
Bruce

Re: Fuel boiling at fuel pump
 

Jeff,

It was a lot of "city" driving. Stop and Go. I had stopped at Alex's house to assist him with his '35 tudor. When I fired it back up after a half hour of sitting I made it a 1/4 mile and she was locked up tight.

Re: Fuel boiling at fuel pump
 

I have done some reading on this subject. I feel that here in Illinois we have the worst gasoline in the U.S.

JM35Sedan is right on. I need to do the following:

1. Raise the boiling point of the 10% ethanol blend.
2. Cool the fuel near the mechanical pump and the line to the carburetor.

I was reading some discussion on an AACA forum about this topic. I can insulate the fuel lines near the pump and the carburetor to help deflect the heat. This will help keep the fuel cooler.

Some folks are adding a 5% blend of Kerosene or Diesel fuel to a tank full of 87 octane, 10% ethanol gas. This will lower the octane rating of the gas. However, they claim since our flathead V8's have a lower compression rating that it will not "Knock".

For now I am going to insulate my fuel lines and try to figure out a way to deflect heat away from the mechanical pump. I have a phenolic carburetor spacer already. I really hate that all of these attempts take away from the originality of the car but that it what it seems like it has come to if I want to drive and enjoy my V8's in the summer time.

Re: Fuel boiling at fuel pump
 

Seth, the heat shield material I used for the line from pump to carb is made my DEI and I got it at our local Auto Zone. It's the right diameter and comes with the heat shrink tips to keep it in place. I haven't fully tested it yet, but at least when I touch the line (inside the shield) it's not hot....so here's hoping!!

Dick.

P.S. Chap, I think your wife's clothes pin theory is spot on!!!