Rick,
First of all, a carburetor does not have a diaphragm. It might have a
float bowl with a float in it, but no diaphragm. Replacing the fuel pump
diaphragm is probably the easiest thing you can do. Simply remove the cover from
the pump, remove the old diaphragm, install the new one and replace the
cover. Screwing with the idle and high speed jets is like doing brain surgery
on someone who simply has indigestion.
Trust me on this one. The fuel pump works off of vacuum that is created by
the internal workings of the engine. When he said it would only run on high
speed (throttle wide open) I knew exactly what it was. It's sucking gas
through the fuel pump into the cylinders, bypassing the carb. Ta Dah!
Rummy
In a message dated 8/27/2009 5:17:06 P.M. Eastern Daylight Time,
sloopblueheron at gmail.com writes:
Cool it, Rummy. This is a constant fuel velocity design that is running
full out. A simple idle control adjustment should be tried before major
surgery. If there is a diaphragm problem, the carburetor diaphragm (if
there is one) is a more likely culprit with gunk holding it down to let in
too much air. A detergent additive or a tank of high detergent gas could
solve it.
With these engines, the quality/stability of the engine oil is more
significant than the quality of the gas. I stick with OMC's products just
to be safe.
Rick
