intermittent loss of power

[kiwi]

I have a 175hp V6 2 stroke (about 1995). For the last 6 months I have had a range of alarm problems which my dealer has worked thru. This has involved extensive cleaning of fuel system, replacement temp sensor, and replacement fuse holders in motor. The remaining problem is that after running at high speed say 4200-4600 rpm the motor starts to run rough and loses power, increasing to WOT gives about max 4500rpm vs usual 5200. Prior to the last visit to the dealer all the alarm indicators would start flashing when the buzzer sounds. Now there is no buzzer or flasing indicators, just the power loss and rough running. Problem seems intermittent or only arises after running at high power for a period (I'm not quite sure). The dealer mechanics are stumped. can you help please.

thanks
Tony

[TMD]

Possible vapour lock situation. The fuel is bubbling in the fuel lines. Put a clean hose in place and keep an eye on it.

Or

Check the fuel for water.

TMD

[kiwi]

thanks for the ideas. we did further checks and found that when the engine was down on power there was still plenty of fuel reaching each cylinder as shown by taking of the air inlet and looking into the throats when the engine was runnning.

Subsequent checks showed a poor electrical earth connection to the electronic ignition unit. Since fixing that the problem has not recurred. Fingers crossed!