2004 Sportser LE DI Jetboat Misfire

[littleg15uk]

I just purchased a 2004 Sportster LE DI Jet Boat with low usage. First time out it ran great for 30 mins, then started to mis fire which progressivly got worse. I thought it may be the gas as it had been in since last summer although the boat was stored in a warm factory warehouse all winter, anyway totally drained the fuel tank. Checked and changed Spark plugs as they were really badly carboned up. Took it out again with fresh gas, once again after about 30 mins started to mis fire. The plugs are oiled up this time. Anyone had similar problems and how were they resolved?
Thanks. Gordon

 

[seadoosnipe]

RAVE valves...

Check your RAVE valves. They may need to be cleaned. If the guillotine slide valves get carbonized, they stick causing problems similar to what your describing. Yours are also driven off your compressor so check the air lines for blockage.

Another thing that may cause these conditions is the water regulator at the back of the exhaust. It looks like one of your RAVE valves but its a water regulator........make sure there is no blockage in the fitting underneath it and that the small water lines blow clear.

 

[littleg15uk]

still same problem

Well after 5 weeks at the dealership we finally got the boat back along with a huge labor bill yesterday, they checked things like Rave valves, fuel filters, fuel pressure, compression tested the cylinders, airline pressure, waterline pressure,oil pressure etc etc and still its just the same:boxing_smiley: Only thing they found was compression in both cylinders was only 100. So now its back again as they said they would refund labour if it turned out to be an engine fault covered by the B.E.S.T warranty but I honestly think they have no idea. Sounds like they pretty much checked what you suggested, any other idea's before I get an even bigger labor bill? Thanks.Gordon