Stomburg 97 accelerator pump

[qmdv]

Accelerator pump not working. Is the leather cup supposed to be tight inside body

[Bored&Stroked]

It will swell once it is in liquid. You should be able to disconnect the pushrod and test it by hand - you should feel the gas fluid and the slight pressure and see the squirts from the accel tubes. If it just pushes down with no observable drag, then check and see if the pumps have the little round/coiled spring underneath the leather cup. I've never had a problem with the leather ones. About the only other thing that can cause an issue is having the floats setup such that the fuel level is so low that it is not getting into the accel pump well. Let us know what you find . . .

[qmdv]

These carbs were rebuilt about 5 years ago. These projects seem to take a lot of time. I put them on the engine last January and the pumps worked well. Could see and here them squirt. Now you cannot. So I took one apart and it seems as if the leather is pretty loose in barrel. Not an expert on this but it appears that the leather does not do the pumping but seals off that chamber and the inner part of the pump does the pumping. These were new pumps five years ago. Rather than swell up in the gas it looks as if they have shrunk

[qmdv]

When you put the pump in the barrel it just drops in with no resistance. If you turn it upside down it just falls out. No resistance.

[Bored&Stroked]

You can buy new pumps from Summit for about $9 each - probably the easiest thing to do. If the leather has dried out, sometimes I've got away with soaking them in water a bit - but that was when I was in a pinch. I'd just buy new pumps.

[cmbrucew]

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Drop it in some MMO for half an hour. Should soften up.
Bruce

[qmdv]

MMO is considered by some to be magic. Know a guy with a very old airplane that has a radial engine. He puts in his gas tank at every fill up.