Fuel boiling at fuel pump

[Seth Swoboda]

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?

[Vics Stuff]

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

[Jembow]

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

[Seth Swoboda]

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.

[RKS.PA]

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.

[5851a]

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Was there any corn in that fuel?

[Seth Swoboda]

Originally Posted by 5851a

Was there any corn in that fuel?

Yes the typical 10% blend 87 octane.

[VeryTangled]

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?

[JM 35 Sedan]

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.

[Lawson Cox]

Originally Posted by Vics Stuff

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

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

[Brad Hole]

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!

[corvette8n]

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.

[cmbrucew]

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

[Lawson Cox]

Originally Posted by Brad Hole

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!

Old wives tale.

[chap52]

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!

[JT FORD]

Does Illinois even sell gas without corn???

[cmbrucew]

Does Illinois even sell gas without corn??

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

[Seth Swoboda]

Originally Posted by VeryTangled

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?

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.

[Seth Swoboda]

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.

[RKS.PA]

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!!!

[Vics Stuff]

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

[Seth Swoboda]

Originally Posted by RKS.PA

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!!!

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.

[jagnweiner]

Originally Posted by JT FORD

Does Illinois even sell gas without corn???

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.

[Seth Swoboda]

Originally Posted by jagnweiner

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.

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.

[jagnweiner]

Originally Posted by Seth Swoboda

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.

Bummer. I guess that's one advantage of N IL. (Another being a few degrees cooler) ;-)

[revkev6]

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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.

[Seth Swoboda]

Originally Posted by revkev6

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.

I think this will help. Although I'm not sure it will completely remedy this situation.

[Seth Swoboda]

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?

[RKS.PA]

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.

[Tinker]

Originally Posted by revkev6

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.

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.



.

[JM 35 Sedan]

Originally Posted by Seth Swoboda

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?

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.

[ford38v8]

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.

[JSeery]

There have been several past threads on using a return line. Can't remember if they were on the Barn or HAMB.

[Tinker]

.... I was going to ask if you run a glass bowl pump, I see you do run a sediment bowl fuel pump.

[expavr]

Originally Posted by ford38v8

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.

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.

[Seth Swoboda]

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?

[Drbrown]

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.

[VeryTangled]

Originally Posted by Seth Swoboda

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?

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.

[Tinker]

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.

[ford38v8]

Originally Posted by Tinker

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, 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.

[Seth Swoboda]

Originally Posted by Tinker

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,

You have a valid and important observation. Our engines, at least in a flathead Ford 1953 and older, have relatively low compression. The fuels we use now have higher octane ratings. The flathead will run on and was designed for lower octane fuel. I mentioned before that I was reading some AACA forums on this topic of vapor lock and lower boiling points in gasoline today. Some of these guys who were driving prewar Cadillac's and Packard's were adding a 5% kerosene blend to a tank full of 87 octane gasoline to increase the gasoline boiling point. They found that because of the lower compression ratios their engines were able to run on the 5% blend of kerosene without experiencing engine knock. Some of these guys claimed it helped reduce or eliminate their vapor lock issues.

[tubman]

Originally Posted by VeryTangled

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 used to do that too, before I got my Optima battery, and it worked. People would walk up and look in expecting to see some chromed over monster engine with lots of finned aluminum parts. They'd walk away with an odd look on their faces.

[ford38v8]

Originally Posted by Seth Swoboda

Tinker,

You have a valid and important observation. Our engines, at least in a flathead Ford 1953 and older, have relatively low compression. The fuels we use now have higher octane ratings. The flathead will run on and was designed for lower octane fuel. I mentioned before that I was reading some AACA forums on this topic of vapor lock and higher boiling points in gasoline today. Some of these guys who were driving prewar Cadillac's and Packard's were adding a 5% kerosene blend to a tank full of 87 octane gasoline to reduce the gasoline boiling point. They found that because of the lower compression ratios their engines were able to run on the 5% blend of kerosene without experiencing engine knock. Some of these guys claimed it helped reduce or eliminate their vapor lock issues.

Seth, with all due respect, I think you have it backwards about the boiling point of gasoline. Today's gas is highly volatile, which means that it vaporizes (boils) at a lower temperature. I hadn't heard of adding kerosene to affect the volatility, but it does sound like it might help that issue, but what does it do to the octane?

[Seth Swoboda]

Originally Posted by ford38v8

Seth, with all due respect, I think you have it backwards about the boiling point of gasoline. Today's gas is highly volatile, which means that it vaporizes (boils) at a lower temperature. I hadn't heard of adding kerosene to affect the volatility, but it does sound like it might help that issue, but what does it do to the octane?

LOL, yes I did and I corrected it. I was inhaling too many gasoline fumes I guess

Adding kerosene will lower the octane rating, slightly. I don't know how to quantify the reduction in octane rating adding a 5% blend of kerosene to say 10 gallon of gasoline. Obviously that is 2 quarts of kerosene in 10 gallon of gas. It was the observation of the AACA guys that it did not cause engine knock. Their thought was it lowered octane to perhaps 85.

[revkev6]

I just went and looked at the msds sheet for lucas top end lubricant and guess what, it's listed as 60-100% paraffin aka kerosene.... so...

[Seth Swoboda]

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Originally Posted by revkev6

I just went and looked at the msds sheet for lucas top end lubricant and guess what, it's listed as 60-100% paraffin aka kerosene.... so...

Well that is interesting. Now, how does the price of the Lucas top end lubricant compare per quart to straight kerosene?

[revkev6]

Originally Posted by Seth Swoboda

Well that is interesting. Now, how does the price of the Lucas top end lubricant compare per quart to straight kerosene?

not well

[G.M.]

I put a small fuel return back to the tank right after the pump. I used
if I remember about a 1/16" orfice hole to restrict the amount returned.
To much return will starve the engine at high speeds. The return allows
cool fuel to flow through the pump at idle cooling the pump. One picture
shows parts to have a temperature controlled fan blow air on the pump.
The other picture shows the return line into the filler neck. The return
line has been on for a number of years and still works. I tried 4 times
and pictures didn't upload, will try to add them later. G.M.

[NealinCA]

Bringing this up, as I experienced this yesterday. I drove 40 freeway miles with no problem, then drove through town, stop light to stop light, then pulled into the In-N-Out Burger drive through line. Idled for 10 minutes, engine temp got up to 200 and it shut down, would not restart. I rolled into a parking spot, pulled the line at the carb, cranked it over and no fuel out of the pump. Let it sit for 30 minutes with the hood open and it fired right up like nothing was wrong. This is the 2nd time I've experienced the problem, but 1st time I've pinpointed no fuel from the pump to carb.

It's a 59AB, with the glass fuel bowl style pump, 2 97's with 1/4 phenolic spacers on an Edelbrock regular hi-rise intake, with the heat risers plugged.

Has anyone come up with a magic solution? I didn't think about taking the ice out of my drink and cooling the pump, but there has got to be a better way...

Thanks,

Neal

[Tim Ayers]

Originally Posted by NealinCA

Bringing this up, as I experienced this yesterday. I drove 40 freeway miles with no problem, then drove through town, stop light to stop light, then pulled into the In-N-Out Burger drive through line. Idled for 10 minutes, engine temp got up to 200 and it shut down, would not restart. I rolled into a parking spot, pulled the line at the carb, cranked it over and no fuel out of the pump. Let it sit for 30 minutes with the hood open and it fired right up like nothing was wrong. This is the 2nd time I've experienced the problem, but 1st time I've pinpointed no fuel from the pump to carb.

It's a 59AB, with the glass fuel bowl style pump, 2 97's with 1/4 phenolic spacers on an Edelbrock regular hi-rise intake, with the heat risers plugged.

Has anyone come up with a magic solution? I didn't think about taking the ice out of my drink and cooling the pump, but there has got to be a better way...

Thanks,

Neal

Neal:

There was fuel in the glass bowl when it wasn't coming out of the line?

Tim

[hotrodart]

The magic solution is to not use ethanol laced fuel......it has a low boiling point compared to real gasoline. Also, my understanding is that fuel in your area is particularly poor in quality.......at least according to folks who live there.

[NealinCA]

Originally Posted by Tim Ayers

Neal:

There was fuel in the glass bowl when it wasn't coming out of the line?

Tim

Yes, fuel bowl was full. And tank was filled 20 miles prior.

[1931 flamingo]

Put in an elec pump (flow thru) near the tank and use it to prime the fuel pump.
Paul in CT Interesting that it got that hot idling in the food line??

[Aarongriffey]

I had horrible vapor lock problems on my ‘46 V8. Especially in stop and go traffic on hot days.
I went back to single exhaust and never had the problem again.
This week I am installing a new gas line on a ‘46 Mercury with dual exhaust system.
The fuel line was two inches from the left exhaust pipe and the electric pump was four inches from the rear of the left muffler.
I am putting the new fuel line on the OUTSIDE of the left frame rail to lessen the chance of heating the fuel and vapor locking.

[shoe box Jack]

cloth pins worked for me. Jack.

[shoe box Jack]

clothes pins worked for me. Jack.

[demingboy]

Many years ago vapor lock was caused by moisture in the gas tank. Only way to cure it was remove tank. Drain all fuel and let it dry. Probalby not the same problem but back in the late 60,s it worked for me.

[ford38v8]

Originally Posted by 1931 flamingo

Put in an elec pump (flow thru) near the tank and use it to prime the fuel pump.
Paul in CT Interesting that it got that hot idling in the food line??

This is precisely when it gets that hot, when the flow of fresh air under the hood slows to allow temperatures to rise. Compare your temperature gauge while on the highway to when you exit and wait at a traffic signal.

[Ken Henry]

I have had issues in the past depending on where a fuel filter is installed, with inadequate delivery when the filter was between the mechanical pump and the fuel tank. I think that the pump has an easier time pushing fuel through a filter than pulling it through... Ken