Fuel boiling at fuel pump

Lawson Cox
I had bought the adjustable electric fuel pump from a local auto parts store about 25 years ago. I since have sold the truck , but I am sure a guy could go their favorite parts store and even order one , or go on line. I am sure they are still available .
Vic
 
RKS.PA said:
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!!!
Click to expand...

I have some of this heat shield material ordered. I'm going to insulate the line from the tank to the mechanical pump. Then the line from the pump to the carburetor. Then test it.
 
JT FORD said:
Does Illinois even sell gas without corn???
Click to expand...



JT-


Here in NW Illinois non-ethanol is pretty readily available. On most pumps, the 87 and 89 will say "10% ethanol added" and the highest octane (91 or 93) will either say "no alcohol added" or just say nothing.


Not sure what the availability is down south where Seth is.
 
jagnweiner said:
JT-


Here in NW Illinois non-ethanol is pretty readily available. On most pumps, the 87 and 89 will say "10% ethanol added" and the highest octane (91 or 93) will either say "no alcohol added" or just say nothing.


Not sure what the availability is down south where Seth is.
Click to expand...

You can only find "pure" gas around me where there is a lake or marina near by. I tried to buy pure gas in bulk but non of the local fuel suppliers sell it. It also does not remedy what to do when you are away from home on a tour and need to fill up. I have some fuel line insulating material on the way. I'll try this and find a method to deflect heat away from the mechanical pump. I'll report back with my findings.
 
Seth Swoboda said:
You can only find "pure" gas around me where there is a lake or marina near by. I tried to buy pure gas in bulk but non of the local fuel suppliers sell it. It also does not remedy what to do when you are away from home on a tour and need to fill up. I have some fuel line insulating material on the way. I'll try this and find a method to deflect heat away from the mechanical pump. I'll report back with my findings.
Click to expand...


Bummer. I guess that's one advantage of N IL. (Another being a few degrees cooler) ;-)
 
Do any of you guys block the exhaust crossover for the intake? I just pulled my manifold off and blocked it because the fuel was boiling in the float bowls. Haven't run it yet though.
 
revkev6 said:
Do any of you guys block the exhaust crossover for the intake? I just pulled my manifold off and blocked it because the fuel was boiling in the float bowls. Haven't run it yet though.
Click to expand...

I think this will help. Although I'm not sure it will completely remedy this situation.
 
Another thought is the heat soak the fuel pump takes after you have driven on a hot day and shut the engine down. The heat soak is causing fuel to boil at the pump. How do you combat that problem? We can take steps to keep fuel cool while running but what do you guys do when you park and the engine does not have enough time to fully cool to a point that the fuel is not vaporizing?
 
Seth, you've posed a very interesting question. The heat soak or sink does heat the pump as it sits after shutdown. But it seems to me that it's the vapor block "lock" that's in the lines before and after the pump that's keeping fuel from getting to the carb. The pump pumps as the engine turns over, but the fuel in liquid form can't get past the vapor barrier. That's why the electric pumps give that extra push necessary to break up the vapor barrier.

So the point you've raised is that the hot pump also vaporizes the gas so it can't move fuel in liquid form up the line toward the carb, despite the fact that it's "going through the pumping motions".

I'm interested, too, in hearing what others do...in addition to the ice packs, clothes pins etc.

We have the perfect setting here in southwestern AZ to test almost all solutions to dread vapor lock stranding!!!

Dick.
 
revkev6 said:
Do any of you guys block the exhaust crossover for the intake? I just pulled my manifold off and blocked it because the fuel was boiling in the float bowls. Haven't run it yet though.
Click to expand...

I just pulled my block offs (some flat tin with ears, hightech stuff :)) out to heat my carburetor more here in a colder climate. When I lived in the south (sub-tropics) I installed them to slowdown overall heat to the carburetor. Never had an issue.

Since I'm in the cold north, it takes my carburetor 20-30 minutes to heat up the carburetor to really preform well, find myself messing with the choke for a few miles. So out they go. Guess I'll see.



.
 
Last edited:
Seth Swoboda said:
Another thought is the heat soak the fuel pump takes after you have driven on a hot day and shut the engine down. The heat soak is causing fuel to boil at the pump. How do you combat that problem? We can take steps to keep fuel cool while running but what do you guys do when you park and the engine does not have enough time to fully cool to a point that the fuel is not vaporizing?
Click to expand...

This is exactly what happened to me while driving my 35 fordor sedan back home from Tulsa Oklahoma a few years ago. It was scorching hot traveling the Interstates, but I had no problems with VL until my car stopped moving in traffic backups, or when I pulled into a gas station and stopped the engine. When I restarted the engine, it would run okay until the gas in the carburetor was depleted. As soon as the the engine compartment cooled down, the engine would start again and run fine.
 
Last edited:
I never saw this installation, so this is a second hand report of a vapor lock solution: A friend reported that he had used a 1/8" fuel return line back to the tank, to provide a constant replenishment of cooled fuel to keep the pump free of vapor lock. To me, that seems like a good idea to prevent stop-light vapor lock, but a lunch stop would put you back to square one.
 
There have been several past threads on using a return line. Can't remember if they were on the Barn or HAMB.
 
.... I was going to ask if you run a glass bowl pump, I see you do run a sediment bowl fuel pump.
 
ford38v8 said:
I never saw this installation, so this is a second hand report of a vapor lock solution: A friend reported that he had used a 1/8" fuel return line back to the tank, to provide a constant replenishment of cooled fuel to keep the pump free of vapor lock. To me, that seems like a good idea to prevent stop-light vapor lock, but a lunch stop would put you back to square one.
Click to expand...

You will need an electric fuel pump at the tank for the return line to do its job. I had a vapor lock condition on a hi-performance hemi engine that experienced vapor lock even with an electric fuel pump at the fuel tank pushing 92 octane fuel to the engine. I ended up installing a fuel return line which solved the vapor lock condition. I chalked it up to the fact that the fuel line acted as a heat sink where it was mounted on the chassis and since the fuel “deadheaded” at the carb there wasn’t enough airflow over the fuel line to keep up with the heat buildup of the fuel passing thru it which led to the vapor lock condition.

What is interesting regarding our Ford vehicles is that I’ve never had a vapor lock on the truck and after reading this thread think that the reason is the fuel tank in the tonner is in the cab with a relatively short fuel line from the tank to the pump so there isn’t as much chance for heat buildup in the fuel lines as on the passenger cars and the airflow thru the engine compartment on the truck is also more unobstructed with very large openings in the inner fenders to allow air to flow past the engine.
 
I believe G.M. was experimenting with a return line at one time. There are a lot of technical things to consider when engineering a return line. Perhaps G.M. may chime in here and opine?
 
The former owner of my '47 installed (1) the foam & foil heat shield wrap on the gas line leading to the mechanical pump, (2) an electric Airtex emergency/starting pump at tank, and (3) substituted a six-blade truck fan for the stock four-blade fan .... it moves a lot of air thru the engine compartment but is noisy at high rpm i.e. in first and second gear.
 
Seth Swoboda said:
We can take steps to keep fuel cool while running but what do you guys do when you park and the engine does not have enough time to fully cool to a point that the fuel is not vaporizing?
Click to expand...

Hi Seth, On days when I'm concenred about vapor lock, I park with the hood open when I know I'm going to be moving again soon.
 
I'm going to make a very uneducated assumption. So octane is around 89-91 now. In the 30's around 50-60? How much could that make a difference to it's stability?



Non Eth has been good to me however.
 
Tinker said:
I'm going to make a very uneducated assumption. So octane is around 89-91 now. In the 30's around 50-60? How much could that make a difference to it's stability?



Non Eth has been good to me however.
Click to expand...

Tinker, Low octane has its own set of problems, but in this modern world, we're dealing with another set of problems that comes with the oxidants incorporated in gasoline to improve air quality. The condition that affects us most is the high volatility of gas today. Just look at it crosseyed and it evaporates, leaving you with an empty carb bowl, or a vapor locked fuel pump.
 
You must log in or register to reply here.
Back
Top