SportJet 90 rev problem

[bastienlaf]

SportJet 90 rev problem

Hi everyone ! I am from Quebec and I am new on the forum looking for advice on my boat repair. Last week I bought a badass Thundercraft Typhoon with a SportJet 90 from a friend. I paid almost nothing for the boat, my friend who really don't have any mechanic skills thought the engine was dead. So i brought the boat home and began working on it. First thing first I hooked up the battery to a charger and let it charge overnight, the day after I tried to fire it up and TADAM!! nothing happened.. So I started looking for a problem which was not a big deal : I bought a new batt. cleaned the wiring connector on the starter, brushed every connectors and looked for broken wires. After a few hours it finally powered up, i got power on the starter, blower, radio.. everywhere, so I filled it up with gaz and took it to the lake, once I got on the lake i fired the engine which was running pretty good on idle, the problem was when I push the throttle lever, the boat start moving but I could not get the boats off the water it was doing maybe 10mph max, I felt the engine was having a bad time revving up. I made myself an adapter to hook it to a garden hose so i can run it out of the water.

Anyone ever face a similar problem? I just wanna know where to start with that engine,

What I know so far:

ENGINE : SportJet 90 S/N: OE100091
Stator: Red
Spark Plugs: Brand new good spark on all of them (not tested with a tester tough)
Fuel filter: Brand new
Oil Injection: Broken (From what I was told by the last owner) and it looks like it's an electric pump (not oem??)
Ride Plate: Looks good not bent seal in place

Any advice would be greatly appreciate!! I would love to drive it before it gets too cold (which is pretty soon in my country)
Thanks !

[bernie]

I would run it off a separate fuel tank like a 6 gallon to eliminate the boat fuel system from the problem. Might also be stretched fuel pump diapragam - has it ever had a fuel pump kit?

[bastienlaf]

I dont know if the fuel pump kit has been made or not. I think running it with a separate fuel tank is a good idea as there was old gaz in the tank and the fresh mix I filled the tank with was a bit rich in oil , about 30:1 . Do you think it can be the rev limiter or something else?