VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 39 won't run past ~25 MPH

Last week my brother, and his retired mechanic friend, reset points, carb float, checked manifold valve. Still ran the same. Then some innovation: removed gas line from fuel pump to carb. While manually pouring gasoline into carb, started, revved engine and watched fuel flow from fuel line. The flow remained unchanged. If it is a problem in the tank (such as debris being sucked down at higher flow rates) at higher revolutions the gas flow "should" have been weaker. They took the precaution of catching the flowing fuel into a container. My brother has medical tests this week but we are still on the malfunction.

I've got three fuel filters. One in the fuel pump,one before the carb., and one before the fuel pump. I can't see how it would hurt,other than some point deduction. A fuel tank 74 years old almost has to have some crap in the bottom. I drained mine twice using the valve under the tank. Good luck on solving the problem.

You can comfirm/eliminate the tank as the problem fairly easy. At the fuel pump, disconnect the line from the tank and install a fitting for a hose; put a gas can inside, no smoking, run a hose, fuel rated, from the pump to the can. Fire it up and see what you have now with no tank in the loop. At least you can start narrowing the source.

Someone mentioned plug wires, Did you install new wires? Use copper wire and not graphite plug wires.

New condenser? New not NOS.

New 6 volt coil? $15-$18 at your local parts store.

Try installing a 6volt electric fuel pump. Your cam may be worn and at higher speeds it wont be able to keep up under load.

At around 50 mph, my '31 starts to buck and I turn on the electric fuel pump and it stops bucking runs fine. No problem driving all day at 50-55mph.

Check the gas cap for vent holes. Make sure you have a vented gas cap on the tank.

I know it was mentioned, but have you dropped the exhaust. Mice can build nests or even baffles can come loose in mufflers and they can block the outlet.

...You mentioned you "reset" the points...You may want to start with a new set + a condenser and clear that possibility out of the picture...if that doesn't solve it then I'd be suspicious of a fuel blockage at the tank...happened to me...Good Luck and Keep us Posted...Kevin

A fuel blockage within the gas tank is very possible.