omc 115 runs rough loss of power....VRO?

[Hobie17]

good day....i have a Fling (14' jet-boat) with an OMC 115 tubojet, it ran fine at the end of the season, after the winter, it started right up on land and ran fine while wake-boarding, then while running full throttle, it bogged down and died, if fired right up, but ran very rough as though something was in the gas.....i changed the fuel (via a portable tank connected to a new fuel filter....pulled the carbs off, took them apart, they were both very clean.....it started right up, i thought the issue was corrected, but i tested last nite and again no power, runs rough, with 2 people in the boat i can get it to plane (plainfully slow, with lots of weight up front) but no where near the speed it should have.....i do notice that there is not much fuel in the filter so now i'm wondering if the VRO pump is shot?? - any help on this is much appreciated.....thanks!

 

[wilde1j]

Re: omc 115 runs rough loss of power....VRO?

Are you sure it's not overheating?

 

[Hobie17]

Re: omc 115 runs rough loss of power....VRO?

thank you for the quick reply, it much appreciated......it's not overheating....i was thinking it was the pump due to the small amount of fuel going into the filter....other than that i was thinking one of the fuel lines (from the filter 'out' to the carbs) could be clogged, however if that was the case i would think i would have found sludge (or something) in the carbs....so typically if the pump is bad would the engine start? and would it run rough? or is there something else i should be looking at?

 

[Dhadley]

Re: omc 115 runs rough loss of power....VRO?

Start with the basics. Check compression and spark first. If that's OK the it's time to look at the carbs.

 

[Hobie17]

Re: omc 115 runs rough loss of power....VRO?

sorry for the delayed thank you, been sailing ~~~~(\_~~~~ - looks like you made the right call, there is 0 compression in one cylinder, the others have 120-125 - since the engine runs, i changed the head gasket, hoping that was it but same problem with a new head gasket, compression = 0......there is no apparent scratches on the cylinder walls, the piston moves freely, everything looks normal.....any other possible causes, other than rings??

 

[wilde1j]

Re: omc 115 runs rough loss of power....VRO?

Broken ring(s), cracked cylinder, warped head are some possibilities.

 

[ezeke]

Re: omc 115 runs rough loss of power....VRO?

Sometimes you get lucky and loose a ring without scoring the cylinder.

Take the bypass cover off and take a look at the side of the piston, you may be able to see if the ring(s) look OK from that side. .