1998 yamaha 250hp wont start.. fire from prop

[robaloroger]

The motor is a sx250txrw. I just bought the motor and it has been sitting for a couple years. I cleaned the vst filter and the other fuel filter. The motor stumbles and backfires. I was looking at the prop and the last time it back fired I saw a 1' flame come out of the prop. I then disconnnected the battery and came here. This cant be normal. The compression is good and I have spark on all cylinders. The fuel pump in the vst was not turning on when the key was in the on position so i swapped it out with a 99 sx200txrx. I know the vst tanks are different but I heard the fuel pumps are the same. If I am wrong please correct me..

 

[multimech]

Re: 1998 yamaha 250hp wont start.. fire from prop

The fuel pump is not going to cause a flame out of the exhaust (prop). check your keyway on the flywheel and see if it has sheared, and the flywheel has moved. This will change the timing, which could cause a flame out of your exhaust. Check everything else if this motor has been sitting for a couple of years.