Need Advice!!

[abrown1434]

Hello All!
I need some help. First off I'm working on a 1986 Mercury 45hp classic 50 4cyl engine serial number 0A996271. Now a little history. This engine is on a bass tracker boat that I got from my dad. This boat means a lot to me from many memories and I want to get the engine running. The boat has set the last couple years and the last time my dad ran it engine was running very rough. Here's what I have found so far:
1. Trigger white wire burnt
2. Stator yellow charge wires burnt

I changed out the trigger and rectifier and currently waiting on stator to arrive (cdi) stator. I rebuilt the carbs fully and set floats etc. with muffs on engine starts easily and will run on its own but is erratic. Will not run in water bogs and dies. Pulled each spark plug made sure have fire on all cylinders by grounding plug to engine block I have spark to all cylinders. Here's we're it gets weird. Pull plug wire off cylinders 1-3 individually while running engine sputters and dies. Pull #4 wire and engine smoothed out. Pulled #4 spark plug very black sooty (brand new ngk plugs). Here's where I thought low compression on bottom cylinder #4. Checked compression (all) cylinders dead on the money at 120 psi!! I know I have spark all cylinders but I can't guarantee it's not intermittent. I don't have timing light so haven't checked timing. I need suggestions what could cause this issue. I know low side stator is bad my resistance readings were 11.5 M ohms with fluke meter. High checked in spec. Any help would be greatly appreciated.
-Aaron

 

[CharlieB]

Re: Need Advice!!

It is quite common for the yellow stator wire connectors to limit current flow, causing heating and discoloration of the wire at the connector. Some owners cut out the connectors and use butt connectors and solder to ensure a very good connection.

A may be a bit too late now, however, Ohm readings alone are not necessarily proof that a stator is defective, DVA testing is the most accurate standard.

Carb cleanliness may be suspect as well as fuel pump output. Rebuild kits are cheap.

A motor that seems to run/idle on the hose yet die on the water is often caused by a lean idle mixture on one or more cyls.

Years of non-use, plus the dying on the water indicate carbs. I highly recommend cleaning, using the rebuild kits with new gaskets.

Once finished adjusting idle mixture you may find most all of your problems cured.

Do you have a copy of the FACTORY service manual?

Check these links

http://1manual.com/Mercury manuals/Service_Manual_Index.html

http://forums.iboats.com/showthread.php?t=309079&p=2072211#post2072211

 

[abrown1434]

Re: Need Advice!!

Thanks for the info! I did rebuild the carbs so I do agree mixture probably off. You did get me thinking tomorrow I'm gonna check the sync again between carbs. It's possible there's some room with improvement there. Also thanks for info on stator wires. I'll keep that in mind when I replace the stator. I couldn't repair the old stator wires they were damaged beyond repair. I do need to invest in a manual. This engine has been a great one. My uncle purchased the boat new and I only recall one time it was worked on I believe for bad switch box. Take care.