Bubbling gas tank

[jtminor]

Bubbling gas tank - on a recent outing with my 1949 Ford F1 the engine kept stalling, finally on the last mile to home it started to run smooth again. When I pulled into the garage and shut the engine down I heard a bubbling sound. At first I thought it was the radiator , but it was the gas tank. After a few minutes I took the gas cap off, a great deal of pressure was released and the bubbling stopped. I have no idea what was going on, any suggestions.

[Terry,OH]

I believe the gas cap should be vented to prevent vacuum or pressure in the tank. I know 40 has the vented cap, I am not sure of 49.

[nelsb01]

1949 Ford passenger vehicles had vented gas caps. How do I know?
Lost my cap on a road trip, and used a plastic bag to cover the filler opening. A rubber band was around the edge to hold it on. At that next stop, the plastic bag had been sucked into the filler opening. Glad I used the rubber band to hold the plastic bag on -- or else it would have gone into the tank.
Try a vented cap and see if that changes things.

[jtminor]

Where can I get the correct vented gas cap ?

[deuce lover]

Here,V8 Ford Sales in Piedmont SC.Maybe Midwest Early Ford in Springfield OH has them also.

FUEL CAPSS LIKE ORIGINAL 32-48 PASS & 48-50 PU

• Year1932-1950
• Item#11C-9030
• Price$12.00EACH

[TJ]

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Originally Posted by deuce lover

Here,V8 Ford Sales in Piedmont SC.Maybe Midwest Early Ford in Springfield OH has them also.

FUEL CAPSS LIKE ORIGINAL 32-48 PASS & 48-50 PU

• Year1932-1950
• Item#11C-9030
• Price$12.00EACH

Napa Auto Parts also carries them. Part #703-1020. I think about the same price. I carry a spare in my tool kit.

[paul2748]

Drill a 1/16 hole in your cap

[jtminor]

What would happen if you drive without a cap on.....

[FortyNiner]

You would likely introduce a steady path for crud in the tank, have a ready source for fuel odor, and invite fumes to find an ignition trigger outside the combustion chamber.

[Lawson Cox]

Originally Posted by deuce lover

Here,V8 Ford Sales in Piedmont SC.Maybe Midwest Early Ford in Springfield OH has them also.

FUEL CAPSS LIKE ORIGINAL 32-48 PASS & 48-50 PU

• Year1932-1950
• Item#11C-9030
• Price$12.00EACH

That cap ain't "Like original" Originals do not have that unsightly "ring" around the outer edge". The entire cap has a smooth and gentle crown from top to edge.

[Lawson Cox]

Originally Posted by TJ

Napa Auto Parts also carries them. Part #703-1020. I think about the same price. I carry a spare in my tool kit.

That cap ain't "Like original" Originals do not have that unsightly "ring" around the outer edge". The entire cap has a smooth and gentle crown from top to edge.My 2¢.

[TJ]

Originally Posted by jtminor

What would happen if you drive without a cap on.....

You can also get a traffic ticket.

[Terry,OH]

Drake reproduces a vented gas cap for the 36-48/50 pick-up It appears identical to the original cap. His part number 18-9030 is somewhat misleading since the early cars did not use a vented cap. The idea of drilling a 1/16" hole in an unvented cap could very well work since that is what Ford had done. I believe the 49 filler uses a smaller cap than the earlier Fords, if so this cap would not work on the 49 car but would should work until 50 on the PU.

[joe 1950]

On my 50 cpe had the stalling problem the cap had plugged up wanted nice chrome one took the one off my Harley worked perfect so i went to my Harley dealer and bought another looks and works great but then again who can see it

[Flathead Fever]

Originally Posted by Terry,OH

Drake reproduces a vented gas cap for the 36-48/50 pick-up It appears identical to the original cap. His part number 18-9030 is somewhat misleading since the early cars did not use a vented cap. The idea of drilling a 1/16" hole in an unvented cap could very well work since that is what Ford had done. I believe the 49 filler uses a smaller cap than the earlier Fords, if so this cap would not work on the 49 car but would should work until 50 on the PU.

What then would vent the tank on a early car if it wasn't the cap? There "must" be a vent somewhere.

[TJ]

Originally Posted by Flathead Fever

What then would vent the tank on a early car if it wasn't the cap? There "must" be a vent somewhere.

As I recall it is vented through the early style gas gauge sender.

[Terry,OH]

Yes the earlier Fords vented the tank through the hydrostatic fuel sender and pick up 32-35. If a vented cap is used on these early cars, fuel often leaks in the area of the cap.

[jtminor]

Drilled hole in Cap, drove about twenty miles, then it stalled again, what do you think is going on...??
vapor lock?
Gas cap?
Dirty fuel line?

This has happened twice this spring.... drove perfect last fall...


Help

[FortyNiner]

Start with a check of the tank and lines.

[Terry,OH]

If it stalled after drilling the hole then remove the cap and see if there is still a vacuum or pressure in the tank. If there is then the hole you drilled is not venting the tank properly.