Now it looses power! 1985 Merc Balck Max 175hp.

[TampaBoater]

Ok, Today morning I went over all the wires that could be shorting, killing my motor as soos as I tilt down. Found some loose, and repaired. I also noticed that there was no wire going from the rectifier to the battery, took care of that. Now, I tried to take the boat out again, got to the water, launched, no probs. After about 8-10 minutes of cruising at around half throttle, the motor starts to slow down on its own, until it stalls, and shuts off. It's not gas, it's got a full tank, it's got a new batter, it's not stator (i think) because the engine does not quit running when I disconect the battery. What could be happening? After that, I tilted up again just a bit, and started the motor again, and ran good tilted up a bit. I am at a loss.
Any suggestions/Thoughts?
Thanks.

 

[ruder]

Re: Now it looses power! 1985 Merc Balck Max 175hp.

sounds like a over heat problem. may cool good at idle but not enough water at higher rpm, maybe impeller has developed a set or maybe you have a oil injection problem, when the motor quits is it hard to turn over right away before you let it cool down.

 

[SparkieBoat]

Re: Now it looses power! 1985 Merc Balck Max 175hp.

what ruder said and then you could do a compression test and spark check...also are you sure your carbs are clean?

 

[TampaBoater]

Re: Now it looses power! 1985 Merc Balck Max 175hp.

@Ruder. I did notice that the pee stream decreased when the motor started to stall. And yes, it becomes difficult to start the engine after it shuts off. The person I bought it from said the water pumps was fairly new. What should I do?

 

[CharlieB]

Re: Now it looses power! 1985 Merc Balck Max 175hp.

With the motor trimmed all the way down or at level and the motor dies, check for spark on each cyl to determine of you have an ignition problem, if spark checks out to be a hot 7/16 inch arc you can be pretty sure your problem is NOT ignition related.

When the motor dies can you hold your hands on the motor block for more than a couple of seconds? If you can hold on it isn't overheated.

It would hurt to test the temp alarm to be sure it works, simply ground the tan wire to the sensor on either cyl head with the key on, warning horn should sound.

That leaves the fuel system, time to clean and adjust carbs, rebuild the fuel pump.

 

[ruder]

Re: Now it looses power! 1985 Merc Balck Max 175hp.

If the motor is hard to turn over when it shuts downm change the impeller just to be sure and it may save your engine,