1992 60 hp Mercury 2-stroke limited to an idle

ericvd

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Oct 23, 2011
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Last week while duck hunting my 1992 60hp Mercury 2 stroke was running great at WOT, and then suddenly lost power like it has in the past when I have run it out of gas. I turned the ignition off to stop and I switched tanks(assuming it was out of gas). I later checked the first tank and found it had NOT been out of gas.

Connected to the second tank I started the engine and it ran it at idle for 60 seconds to make sure I had enough fuel and no air in the line. When I hit the throttle, it wouldn't accelerate. Ran fine idling, but would not get out of an idle. I've had outboards in the past that wouldn't run faster than idle if the oil was low, so I shut it off and checked the oil. The oil was the lowest I've ever had it (just below the tube gauge), but there was still oil in the reservoir(about an inch or more in the bottom of the reservoir). I carry 8oz. just in case and put it in. Now the oil is back on the tube gauge again up about 3/4".

After having been off for 5 minutes or so, I fired up the motor and buzzed WOT to my hunting spot at least a mile away - ran great. When it was time to leave 1 hour later, the engine could not get past an idle. It would act like it wanted to go and had the power when I slammed it down, but it was like the electronics was bringing it back down to an idle. Ran great at an idle. No beeping. No alarm. Water pumping strong. Just wouldn't run past an idle.

In case the oil pump was going bad, I hooked up my 15hp premix tank to ensure engine lubrication and to eliminate fuel line as the problem. This is a different (3rd) tank with a different fuel line. Same results. Idled great. Give it some throttle and it "wants" to go, but acts like someone else is throttling it back automatically.

The next day I tried the 60hp again on original non-mixed gas, hole shot got me out of the water like it normally does, and then 45 seconds later, it acted like someone was pulling down the throttle again. I swapped each of 3 plugs one at a time. Same results after each plug swap. I left motor off for at least 5 minutes, and fired up the motor and did another hole shot and got all the same power like before the problem, and then 10 seconds later, lost power down to an idle again.

Any ideas? Sensor? Coil(s)?

Do I just bring it to a mechanic?

Thanks,

Eric Van Dyke
 
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