Thrust problems 120HP Force Jet

[jaimesahn]

I have a 1995 Sea Ray Sea Rayder 120 hp force jet. I put the boat in the water and discovered that i have poor acceleration. the tachometer under load stops about 3500 RPM and my speed is under 4 MPH. at full speed the boat should be close to 40 MPH at 5500 RPM. Nothing is clogging in the impeller and the wear ring is at a tight 30,000th where it calls for 25,000th. The boat mechanic stated that he did not have a clue what is wrong with this!!! Jaimesahn

 

[Frank Acampora]

Re: Thrust problems 120HP Force Jet

Well, if its not the jet drive, then it must be the engine!

Check compression ratio on all cylinders, check the carbs for full opening. Check for spark on all cylinders. Check timing for correct advance. If all these are OK, then check the entire fuel system from tank to carbs.