Re: 1956 Oliver 5.5 hp won’t start

[Buccaneer]

Yesterday I lapped the two halves of the original fuel pump shown in the photo,
as it had some rough machine marks and was slightly warped.
Tested the pump on the Oliver and it made no difference.
Today the new B&S style pump came.
I installed it and it started right up. Runs good at mid to fast
speed with fuel tank at normal height as it would be in the boat.
At low speed it coughs (starving for fuel) The impulse line on my
new pump is clear line, and I could actually see flame in the line
when it coughed!! Once is starts coughing it will die unless
sped back up. Sometimes it will start back up at "Start" range,
other times it needs a little choke.

I have the low speed needle as "rich" as it will go and it still coughs.
When I had the gravity feed tank on I don’t think it was coughing,
and the high and low speed adjustments were in normal range.
With the original fuel pump at times it would pump enough gas
to keep the engine running, but never at mid to low range.

Are these symptoms suggesting that I don’t have enough
crankcase suction at low speeds to supply sufficient fuel,
and hence, a scored piston or other malady?
It does have lower compression than I’d like to see, but
both cylinders are within 3 psi of each other.

Is it time to tear down the power head for inspection?

Thanks for your wisdom!

Prepare to be boarded!