Won't run over 2K rpm

[ntarver0568]

I have a 1998 Merc 150 offshore. I was out in it about 2 weeks ago and it was running perfect until I stopped and left the motor running, went to go again and it wouldn't run over 2500 rpm after that, but it ran like it was missing. I changed the spark plugs and the starboard side plugs were all wet with fuel and the port side plugs had carbon all over them. I ran it with the earmuffs on it after that and it worked fine until a put it in the water with a load on it. It does run much smoother now, but it won't go over 2000 rpm. I have checked the carbs and they are clean. Checked the plugs again and all 6 had a little carbon on them. Only thing that makes sense to me would be the coil packs since they run 1, 3, 5 and 2, 4, 6 and the 3 carbs run 1 and 2, 3 and 4, 5 and 6. Any suggestions?

 

[sschefer]

Re: Won't run over 2K rpm

I have a 1998 Merc 150 offshore. I was out in it about 2 weeks ago and it was running perfect until I stopped and left the motor running, went to go again and it wouldn't run over 2500 rpm after that, but it ran like it was missing. I changed the spark plugs and the starboard side plugs were all wet with fuel and the port side plugs had carbon all over them. I ran it with the earmuffs on it after that and it worked fine until a put it in the water with a load on it. It does run much smoother now, but it won't go over 2000 rpm. I have checked the carbs and they are clean. Checked the plugs again and all 6 had a little carbon on them. Only thing that makes sense to me would be the coil packs since they run 1, 3, 5 and 2, 4, 6 and the 3 carbs run 1 and 2, 3 and 4, 5 and 6. Any suggestions?

My guess is that the Rev Limiter/Advance module is bad. Check the wiring going over the top of #1 cylinder. Look for anything melted together. I've seen it where the heat gets to the wiring and it breaks down and shorts to the block. That's the wiring for the rev limiter/advance module and if it's shorted it will throw off the bias circuit on the switch boxes.

 

[j_martin]

Re: Won't run over 2K rpm

Stator or switchbox. Sort it out with a maintenance manual and a DVA.

hope it helps
John

 

[ntarver0568]

Re: Won't run over 2K rpm

It was the stator, thanks for the help