Service mode

Dear Friends!

I have a Ski Nautique 1992 with a Ford 351 engine.
The engine is working well when it is cold, but after 5 or 10 minutes driving the service mode is activated. Under 2000rpm it is working well but over 2000 rpm the engine sounds bad and the power is gone.
The temp switch and oil pressure switch is OK.
I would be greatfull if you can help me.

Sven Svensson
Sweden

As mentioned the first thing to try is disconnecting the wires at the oil and temp switches not the gauge sending units. They are normally an open circuit and are grounded when a failure is detected so the protec is looking for an open. Next I would measure the 12Vdc that supplies the protec unit. You can measure it at the 12.5 breaker on the back of the engine. There is usually a glob of rubber insulation over the terminals. Just push the volt meter probe through until you see a voltage reading. The key needs to be turned on for this reading. It should read close to the battery voltage. If you have good voltage then remove the connector on the protec and clean it with alcohol and then try running it again. If the voltage is low then that may be the problem and you will need to make some wiring changes to bring the voltage up. Even if the voltage is low there is also the distinct possibility that you need a new ignition system but I would try the wiring changes first.