Vapor Lock Quick Recovery Tool

[Old Henry]

I've been plagued with vapor lock on this 51 Custom I'm trying to sell for a friend and, until I get Shewman's check valve flex hose I came up with this idea to get back on the road when the engine died after a short stop.

I got a short piece of soft hose.



With the inside diameter the same as the outside diameter of the gas filler neck. (Doesn't look like it in this picture but it is.)



Then pushed the hose down over the filler neck.



And blew.



Works great.

I thought I'd have to really huff and puff to pressurize the tank but couldn't even get one full breath in before I couldn't blow any more in. Then held the pressure as long as I could to make sure the fuel pushed up the fuel line, through the pump, and filled the carburetor float bowl. Then, got in and started it up and drove away.

If this was my car I would immediately install an electric backup fuel pump back by the tank like I did on my 47 but it's not. Hopefully, when I get Shewman's flex hose the fuel will quit draining out of the pump and solve the problem.

[Bassman/NZ]

Dont inhale them fumes!

[WestCoast]

that works but an electric fuel pump installed the fuel line will over come that problem with a push of a button or throwing a switch, but im lazy

[Old Henry]

Originally Posted by WestCoast

that works but an electric fuel pump installed the fuel line will over come that problem with a push of a button or throwing a switch, but im lazy

No doubt. That's what I did on my 47 but am not going to do on this car of a friend I'm just trying to sell and get out on the road enough with For Sale signs on to be seen.

[JSeery]

Does it have a vented cap on it?

Edit: I see we have already been down that road, but it sure acts like a vacuum build up in the tank!

[WestCoast]

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ok Old Henry, sorry , I didn't see the "for a friend" part

[Old Henry]

Originally Posted by JSeery

Does it have a vented cap on it?

Edit: I see we have already been down that road, but it sure acts like a vacuum build up in the tank!

It definitely isn't a vacuum build up because I can pressurize the tank with this hose, push gas clear to the carburetor and fill it, the engine starts and runs until the fuel in the carb is gone then dies, even with not gas cap on at all. So, the brand new pump isn't pumping after awhile even when I've just pumped gas through it and filled it full of gas!

[ford38v8]

Henry, No pump will pull gas if there is no integrity in the fuel line. The smallest air leak will shut down the pump's draw. This will not show up as a fuel leak, either.

An electric pump in a car with a bad fuel line is just a band aid, and in fact, will pressurize the line which will then show any pinholes if present.

[flatheadmurre]

Im loosing all the details spread into different threads...
But if you simply put your tumb at the intake of the pump and it doesnt have a good suction you either have a faulty backvalve, a crack in the diaphragm or the pump being warped or not tighten enough to seal against the diaphragm.
If you have a pump with rubber backvalves they deform from the alcohol in the new gas and start working strange.If its a brand new pump just get it replaced.

[4dFord/SC]

"Well, officer, I was just trying to start my car...."

[dwaynec]

If it only runs until the fuel bowl runs dry I don't think it is a vapor lock problem. IMHO it is a pump issue either because the pump is bad or a vacuum leak.

[Blu Dice]

X 2

[Old Henry]

I have just replaced the entire fuel delivery system from the tank to the carb brand new; fuel line from tank, flex hose, fuel pump, fuel line from pump to carb.

The main characteristic of the problem that is like vapor lock is that the problem is only when warmed up. I parked it at a restaurant yesterday in the shade, 75° ambient temperature, and it still had the problem. So, all I can come up with is a bad brand new fuel pump. We'll see what Shewman's check valve flex hose does when it comes. If that doesn't work the new fuel pump will go back to C&G for another to try, unless someone knows of a better source for a fuel pump?

[expavr]

Could the problem be with the pushrod in the block that activates the pump being worn to the extent that the pump's stroke isn't long enough to provide the correct pressure to the carb? Its been a while since I tinkered with a mechanical fuel pump but as I recall if the lever in the pump just flutters instead of making a full stroke the pump won't generate enough fuel pressure to the carb.

[Old Henry]

Originally Posted by expavr

Could the problem be with the pushrod in the block that activates the pump being worn to the extent that the pump's stroke isn't long enough to provide the correct pressure to the carb? Its been a while since I tinkered with a mechanical fuel pump but as I recall if the lever in the pump just flutters instead of making a full stroke the pump won't generate enough fuel pressure to the carb.

I've had that suggested and have thought about it but I would think that if that was the problem it would be consistent through all circumstances, not just trying to start when warmed up. The pump works great under all other conditions at all speeds. It tests OK with plenty of pressure and flow as well. Very bewildering.

[expavr]

Originally Posted by Old Henry

I've had that suggested and have thought about it but I would think that if that was the problem it would be consistent through all circumstances, not just trying to start when warmed up. The pump works great under all other conditions at all speeds. It tests OK with plenty of pressure and flow as well. Very bewildering.

Have you tried placing a wet sponge/rag on the fuel line at the low point where it breaks up the firewall? I had a similar vapor lock issue on our RV which wouldn't start or would cut off when the fuel line got hot. By trial and error I found that by placing a wet sponge on the fuel filter which was located about 1/2 way down the chassis from the tank cured the problem. The other thing I noticed is that this vapor lock phenomenon only happened when the level of the gas in the fuel tank dropped below 1/4 tank from which I concluded that the cooling effect of a larger volume of fuel somehow contributed to vapor lock free operation.

[Tinker]

Craig, You crack me up man!!!

[Richard in Florida]

Originally Posted by Old Henry

...unless someone knows of a better source for a fuel pump?

Absolutely, based 100% on wonderful personal experience.

Then and Now Automotive

www.then-now.com

Mike Casella is a genius with these old pumps, and he's not out to pay off his boat with your bill.

[Old Henry]

Originally Posted by Tinker

Craig, You crack me up man!!!

As Donald O'Conner used to say, "Make 'em Laugh!" https://www.youtube.com/watch?v=TklrBmHo7Do

Just think how funny that looked stuck at an intersection after the light turned green alternating waiving the traffic by and blowing into my magic blue hose?

[Old Henry]

Originally Posted by expavr

Have you tried placing a wet sponge/rag on the fuel line at the low point where it breaks up the firewall? I had a similar vapor lock issue on our RV which wouldn't start or would cut off when the fuel line got hot. By trial and error I found that by placing a wet sponge on the fuel filter which was located about 1/2 way down the chassis from the tank cured the problem. The other thing I noticed is that this vapor lock phenomenon only happened when the level of the gas in the fuel tank dropped below 1/4 tank from which I concluded that the cooling effect of a larger volume of fuel somehow contributed to vapor lock free operation.

I have tried driving with all fuel lines in engine compartment and fuel pump wrapped in wet towels. No difference. Also run with tank full. It was actually worse after filling up yesterday. That makes me think it's something other than vapor lock - still some kind of mechanical problem. But what?