Gas suction problem(?)

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I am having some fuel problems with my 1930, Model A 7 passenger sedan. this car has run without problems for several years, in the mounains, in hot weather and at higher altitudes. It has a conventional fuel delivery system with an added electric fuel pump, that i only use to prime the carburator during starting and occassionally on hot days when there is a problem with vapor lock. Resently I have had some fuel problems which I thought was vapor lock. I turned on the electric fuel pump and the pboblem went away, only to come back within a mile or so. At this time the car basically stopped. After waiting several minutes I was able to restart the engine and continue on for about 1-2 miles when it started happening again. this continued for about 8-10 times until I was able to get teh car home. I have rerouted the fuel line outside the frame, insulated the exhaust line and also insulated some of the fuel line. The problems continue. You can see what looks like bubbles in the fuel bowl. I am suspecious if I might have an obstruction in the fuel tank/line/fuel pump but was interested if anyone has any specific ideas. Thanks.

[Author nameAuthor names are only available to PAS members.]

If the fuel is pulled from the tank from the top, the fuel pickup line might have a pinhole or a small crack in it near the top of the tank.. This hole or crack allows air to be pulled into the line along with the fuel pulled from the tank.

You may have to drop the tank and pull the fuel pickup tubes out of the tank to inspect them.

On my ’33 836, the pickup tubes in the tank had many small pinholes in the brass tubing.. I mad new pickup tubes from copper. The brass appeared to have corroded from the modern fuel mixtures we have to buy now..

Hope this helps.. Greg L.

[Author nameAuthor names are only available to PAS members.]

Hi Syd, stalled 8-10 times, what a nightmare. I suggest you start and run the car and while parked, slowly increasing the throttle while someone watches the fuel bowl. If it is pinholes in the fuel line, the bubbles should increase with RPM’s as fuel flow tries to increase, the fuel actually chokes down and the engine slowly drops in rpm and dies-running smoothly as it does. If that happens, inspect the fuel tank and system as Greg suggests. If someone is on throttle and as the car dies, it bucks, or surges or perhaps bubbles are less evident in the bowl, it may be a carb issue, such as sticking float, etc.

Best of luck troubleshooting-John

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I have found that the clamps on the gas line (rubber hoses) from tank to electric pump loosen with time and won’t hold a vacuum. Tighting will usually solve the problem. I had the problem with both 32’s.

[Author nameAuthor names are only available to PAS members.]

I have a Model A.They are not supposed to vapor-lock.Mine does.For

years,a good running A was fine mannered in the morning and prone to

die around 3PM on hot days.I applied various aluminum foil,clothes pins

and other vulgar remedies with some success,but the problem would return.

On Rodney Flornoy’s Tour I met a fellow A owner with the same problems.

He had applied space age tech around the gas line.As we were making

comparisons I touched my carb.It was very hot.I believe the gas was

boiling inside it.I’m not sure what the remedy is.

I believe that you are vapor-locking.Your gas line may be too close

to a heat source(gas line routing in past practice,may be too close for modern fuel).Use a heat gun that tells how many degrees an object is.I bet

your carb is trying to break it’s petroleum habit and get hooked on natural gas!I’ve been told that modern gasoline will turn into a

gaseous form at 76 degrees.I tried running a little diesel in my A,but

it didn’t change matters.Any other additives?

Tony Costa

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