OMC 115HP TURBOJET Sometimes does not stay on, going very slow.

Joined
Aug 19, 2012
Messages
10
Hello, I have a omc 115hp turbojet motor on my 1996 sunbird 17', basically the motor turns on with starter fluid and then I turn on the electric fuel pump to have the motor stay on. My problem is that it does not always stay on when its in water, but outside of water it will always turn on and stay on. It always cranks, I put seafoam in the gas tank because I think its a gas issue, I just rebuilt the carburetor but still happens. Im lost here and I basically replaced anything ignition related, I do not have the airbox on the carbs, does this affect it? the spark plugs are new aswell, when it does stay on in the water it only clocks in at 7 mph with 3 people onboard. also sometimes the boat will only turn on in the water when i have the throttle open a bit. any suggestions are greatly appreciated.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,468
Ayuh,..... Welcome Aboard,.... Is the 115 Turbojet an Outboard motor,..??
 
Joined
Aug 19, 2012
Messages
10
ok even though no one is messaging back lol, I took my boat out yesterday to the keys and put the intake air silencer cover on the boat for the first time and now the boat turns on every times so now that issue is resolved, but the boat is still going very slow, i measured only 5 knots which is basically idle speed. my rpm gauge says im at 4500 rpm, at around 75% open throttle, im not sure what else it could be. Any suggestions????
 

rcmslm

Seaman Apprentice
Joined
Jul 13, 2014
Messages
32
Does it pop thru the exhaust when running?Did you check compression?
 
Joined
Aug 19, 2012
Messages
10
no i dont hear any pops, and yes i checked the compression and its fine, the motor works fine and the temperature is at 155 degrees, and it gets the right rpm, I have wake but its not going fast
 

sjbs

Seaman
Joined
Dec 22, 2011
Messages
69
Is the impeller in good shape? How much clearance between impeller and wear ring? Is reverse bucket going up all the way?
 
Joined
Aug 19, 2012
Messages
10
hey sjbs yea i figured it out, i looked up all the parts on the motor and noticed theres a coupler bushing between the motor and the jetpump, im 90% sure its the coupler because i literally checked everythingelse and checked all the specs because I have the manual. but its most likely the coupler because the symptoms sound like a bad coupler since it doesnt go fast on high rpm but on slower rpm it picks up a bit, so most likely the bushing is bad. the only thing is that coupler is $$$$$$ and hard to find, I saw one on ebay for $450 but I wanna look around first to find it cheaper lol
 
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