1995 150 HP Ocean runner won't go over 2500 RPM

I have a intermittant problem on a 1995 150 HP ocean runner that is driving me mad. The motor is lossing the top end RPM. Compression is 100 PSI +/-5 on all six. New plugs, rebuilt all six carbs. One of which had a problem of a missing bowl seal (BB like plug) and was leaking fuel. New bowl and new fuel line pump bulb. Old one was cracked after one season.

Launched boat and it ran normally at first, but at WOT it wouldn't get over 4200 RPM. One day later the boat was run approx 8 miles, WOT 5500 RPMs.

Boat sat for 5 days and now I can't get 2500 RPMs at WOT. Runs rough, it feels like a miss. No alarms of any kind. Could someone please point me in a direction to troubleshoot this? The pump in the fuel line never gets completely firm no matter how much it is pumped. But no fuel leaks from the carbs. I'm stumped.

Re: 150 HP Ocean runner won't go over 2500 RPM

Motor is going in to slow mode, could be many things like temp wire to close to plug wires, power pack acting up, loose ground wire. As for the primer bulb that should not get hard as it is under suction just make sure there is no air pocket where the plastic fuel filter is mounted on the engine, that will cause a lean situation.

Re: 150 HP Ocean runner won't go over 2500 RPM

If the motor goes into slow mode, don't you need to shut it off to reset? The motor will surge to 4000 RPM and back to 2500. The powerpack and optic sensor were replaced by the selling dealer last year just be fore I bought the boat.

Re: 150 HP Ocean runner won't go over 2500 RPM

I had the same problem last year on my 115. turned out to be corroded connector. Mine was on the port side brown and white wires from the temp sensor. Try unplugging the connector and running it just to test, bet it might jump up on plane for you.

Re: 150 HP Ocean runner won't go over 2500 RPM

Hey Zing,
Was your motor stuck in slow mode or was this an intermitant type of issue.

My problem is not 'slow mode' because the motor will be stuck at 2500 RPM then jump up to 4000 or 4500 or sometimes 5000 for a short time.

Also no temperture alarm and very good cooling water pressure 20+ psi at the WOT but low RPM.

I'm still thinking a fuel/carb/hose issue. I haven't look at it for over a week but I'll let you know more, when more is known.

It could be some air leaking hose caused by the 10% corn fuel we get today. Not sure if the motor was designed for that stuff.

John

Re: 150 HP Ocean runner won't go over 2500 RPM

Yes, Mine was a problem with the slow kicking in, though it might have been your issue too.