Engine not running under load. Help!

[Mielke]

I have a 2001 mercury 50 (oil injected) that will sit and idle, and rev up in neutral. Put it under load and it wont leave 2500 rpms and wont plane out. It just bumps along dredging. I was told it could be the high stator has went bad in it. Had a friends boat whose would do the same thing, and he just had a plug go bad so he was only running 5 cylinders. I pulled all 3 plugs yesterday and all were pretty burnt, but one was black as tar and smelled like gas. I replaced plugs but havent ran it yet. Hopefully im lucky and this is the problem. If it is high stator how much do you think im looking at? $$$ could it possibly be the high stator gone bad?

 

[Mielke]

It wont bog down and cut off. It just hums along dredging.

 

[MrWiskers]

Is this fuel injected or carburated? Your carburators may need to be cleaned.

 

[Mielke]

Carb. Boat cranks, idles and revved up too easy for that i thought. I talked to boat mech. Over by hopewell school in cleveland and he told me high side stator. Well what would be ballpark on getting somebody to clean them? This is my 2nd boat and never had one go to the shop before.

 

[Kirk]

I PMed Wrechin2 so he would know to look for your question.

 

[Mielke]

Thanks kirk.

 

[Fishheadspin]

mine did the same thing it was the powerpack..

 

[MrWiskers]

I had the exact same issues with my old Nitro and it was the carbs. Got them cleaned and it fixed the issue.

 

[SNUFFY]

sounds more electrical to me...when you put it in gear (under load)the spark advance comes into play. The stator is part of that system. The linkage between shifter and throttle work together for the spark advance so it possible could be linkage, but my guess is stator system.
New electrical stuff could be a few hundred dollars 2-500 but used can work just as well. Like most electrical stuff , it can be a gamble new or used.
Of course carbs can be tricky too, if you can eliminate them then go to electric. Should be able to test for electric with right equipment

 

[Punisher]

change the plugs and go from there,plugs are 2$ a plug

 

[Liveliner]

Have you changed propellers since it ran Normal? If so, you could be trying to turn too much prop.

 

[wrechin2]

It sounds like a stator from your description as many mercury stators cross over between 2500-3000 RPMS. Most of the time it will pull pretty quick to these RPM's and then hit a wall and most of the time will almost "sound" like it is running out of fuel. This is a CDM engine and the CDM's give quite a bit of trouble and requires special tools (or test parts LOL!!!) to check them out. If it is a carb issue then pushing the choke will MOST of the time cause the RPM's to increase.

Personally I would replace the plugs as suggested and go from there. If it still does not run properly push in the key to find out if the engine picks up or slows down.

IF you have access to a timing light connect it to each plug and watch it at a idle. If there is no "flashing" then there is no spark. If you have not spark on a cylinder at idle then switch the CDM with another cylinder and see if it follows the CDM. If you have "flashing" on all at a idle then have a helper to hold it and watch the "flashing" when it boggs. If a cylinder quits "flashing" then switch the CDM's and see if it follows. If it stays on that cylinder then it is going to be a stator or a trigger. 99 times out of 100 it is the stator.

A CDM is a Capacitor Discharge Module and is basicly a coil and switch box (power pack) built into one. This is what the spark plug wire is connected to. By moving them around you can figure out a lot. This ignition system consist of a CDM, Stator, and Trigger.

Just my .02......

 

[wrechin2]

BTW mercury list on that stator is $240.83.....

 

[Mielke]

Replaced plugs. Hitting choke on engine causes rpms to nose dive. So most likely it is stator. Boat is at shop now getting a real diagnostic test. Lol. Thanks everybody for the replies. I already knew it was an expensive stator. Just hope i dont get slayed on labor.

 

[Mielke]

Liveliner prop is merc original.

 

[procraft]

had the same thing on a johnson 150 it was a stator got a used one and had it put on for 98 and some change call mud creek they may have a used on