bad running mercury 50

[gwgautney]

I have my father in laws mercury 50elpto 2002 2 stroke. It's running bad at all times. Carbs have been cleaned. Fuel system appears to be good bulb pumps up and stays hard. Doesn't appear to have any air leaks. Used a gap tester and there is fire on all three cylinders. It runs bad like is missing or back firing constantly. Does it on the hose and in the water. When in the water it's does it all the way through the throttle from stop to wot. Where do I start. I feel like I have looked at everything that I know to look at so I'm stumped now. Thanks let me know if y'all need anymore information. Powerhead was removed not long ago to repair steering section.

 

[scamp12]

Check for a Intake leak. Sprak some wd40 around the reed plate if. The idle changes there you go .

 

[scamp12]

Spray wd40

 

[gwgautney]

Ok I will try that this evening

 

[yzf125]

You would be better off using brake clean or carb cleaner, you get better results and it will evaporate were the WD40 will leave an oil film on everything. Just my opinion.

 

[gwgautney]

Where is the reed plate is that directly behind carbs? I was trying to find a diagram but I don't have the sn with me all I have is model and can't seem to find the diagram for it with model number

 

[yzf125]

Its between the intake and the case.

 

[gwgautney]

Ok thanks

 

[gwgautney]

I checked intake for leaks this evening and found nothing. While I had the motor running I was checking some of the wiring around the motor. There are four wires on the starboard side of the motor that run up under the flywheel and run back to the back of the motor. I was messing with those wires and when I grabbed them and squeezed them making sure they were connected good the motor died. I cranked it back up and did the same thing and it died again. What are these wires and what do they do. Also they are not color to color. You have different colors on the harness from the flywheel than you do where they connect. Where can I find a schematic that tells me what color to what color to make sure my brother in law didn't cross anything up when he removed the power head.

 

[gwgautney]

The serial number for that motor is 0T425025 And it's a 2002 50ELPTO

 

[DavidMoore]

Sounds like you need to check everything is clean and tight and check all insulation for damage / shorts.
Attached is probably the diagram you need. For sue get the manual for your engine and all the info you need will be there.

 

[gwgautney]

Ok thanks that will help a lot. I haven't gotten a manual because it's not my motor. I thought it was going to be something simple but looks like I may have to pick one up.. Any other ideas why this motor is doing this if it's not the wiring?

 

[gwgautney]

Also it's there anything that would have caused this from pulling the power head? Maybe something they didn't do correctly upon reinstallation? My brother in law is a decent mechanic but I have had to go back and fix things behind him a time or two. Just wouldn't know what to check behind him

 

[yzf125]

Those wires sound like the stator wires, Yellow should be connected to Yellow, ( Charging ) Green White to Green White and White Green to White Green ( Ignition ). Check the sleeve shields for being melted and make sure there is dialectic grease on the connections.

 

[mlbinseattle]

Also, check each and every one of the nuts that secure each wire to the posts on the power pak and the coils. Sometimes, those look tight but aren't. Pushing on a wire lug can cause those nuts to become loose if it wasn't already tight enough.

 

[yzf125]

His motor has CDM modules with a plug connection.

 

[gwgautney]

The wires are purple brown white and black coming from under flywheel

 

[yzf125]

Those are from your Trigger and they go directly to your CDM modules ( Coils )

 

[gwgautney]

Ok I am getting fire to the plugs is it possible they are grounding out and throwing them out of order

 

[yzf125]

Are you sure they are connected correctly ? Could be firing the wrong cylinders if not connected right.