Well, once again I'm stumped by fuel problems on mom's GT18. I cleaned the carb and put new gaskets and needle in it when we first bought the tractor. I also rebuilt the fuel pump that's on the side of the carb and replaced the fuel filter.
It ran fine for a couple weeks, but then started cutting out, etc. I replaced plugs, and points, and checked the fuel line for leaks--everything was fine.
I installed a low pressure electric fuel pump--again helped for a few weeks and then same problem again-- rough running, stalling out, sometimes black smoke coming form exhaust.
I removed the electric pump, and replaced the line from the crankcase to the pump. Also cleaned the gas cap and made sure it was venting. Also made sure the dip stick was sealing.
... it worked for about 3 months then the same problem started again.
Mom thinks that it might be a pinched fuel line-- which I will check out.
The only other thing I know that it might be is that it has somewhat low (85-90 psi) compression, but both cylinders are withing 10% of each other. Could low compression make it so the fuel pump doesn't have enough suction? I have 4 machines with Onan twins, and, with the exception of my GT 18, they all seem to be fussy this way.
I need to get this repaired today so I can get it back to mom this weekend. Any advice would be appreciated.