Stewart-Warner 240A fuel pump question

[Jim Rosenthal]

We are having trouble with the pumps in 1149, which lose prime as soon as you shut them off, and then won't reprime. The pumps run in parallel, drawing through a Spitfire selector valve from the two tanks. The pump outputs are then merged to go into a single fuel line, to the filter/regulator unit, which has a glass bowl, and from there to the Weber carbs. When you shut the pumps down, you can see the fuel filter bowl drain immediately.

I don't recall this happening before. Does anyone know enough about 240A pumps, which haven't been made since I think the 70s, to know if they have an anti-drainback feature in them? this is maddening.

 

[Davidmgbv8]

We are having trouble with the pumps in 1149, which lose prime as soon as you shut them off, and then won't reprime. The pumps run in parallel, drawing through a Spitfire selector valve from the two tanks. The pump outputs are then merged to go into a single fuel line, to the filter/regulator unit, which has a glass bowl, and from there to the Weber carbs. When you shut the pumps down, you can see the fuel filter bowl drain immediately.

I don't recall this happening before. Does anyone know enough about 240A pumps, which haven't been made since I think the 70s, to know if they have an anti-drainback feature in them? this is maddening.

Possibly an air leak on the suction side? Seen that happen on race cars with braided AN hose

 

Yes, I would suspect an air leak Jim. I run two 240As and, while the lines gradually empty after shut-off, the pumps prime up and fill the filter/lines within 2-3 seconds when switched back on.

 

[Jim Rosenthal]

Air leak on the suction side.... that makes sense, because an air leak on the pressure side would leak fuel... I'll see if I can find that..