Merc troubles.

[irishfan]

I have a 6hp merc 86/87 year. It has no spark at the bottom plug and runs rough. I think the switch box is bad for the coils. Not sure about any other problems. How much is the motor actually worth before I sink a bunch of $$ into it? Don't want to spend $400 and it only be worth $500.

 

[switchback]

Well not sure if this helps but I just sold a boat with a 86 9.9 merc on it. On one trip to the lake it quit getting fire. It ended up being the power pack inside with all the wires, not the coil packs. The mechanic said most of the time on mercs that is what the problem is. I looked on line and got the part new from Florida for $100. every boat dealer wanted double that.

 

[irishfan]

It is the power pack thats bad. Both cylinders compression check at about 85 psi. Should I even bother putting any money into it?

 

[cajuncook1]

It is the power pack thats bad. Both cylinders compression check at about 85 psi. Should I even bother putting any money into it?

If your switchbox/powerpack is bad and it is running on one cylinder then yes it will run rough(reduced power**only cylinder is contributing) and idle very poorly.

Couple of questions:
- Was the engine running ok prior to this. (powerpack can give out without warning)( IF it is the original power pack then it has given 22 to 23yrs of good service.
- If you were happy with the motor prior to all this, then I would say this investment is worth it. I mean can you find another reliable motor for $400 to 500 dollars. Most motors are of unknown quality that you might have to invest more money to get to run?

-Have you thought of replacing the power pack yourself?
Here is a link to Sierra brand switchbox/power pack for your motor.(it is a little over $100 there is also a Mallory brand as well for about the same price) (please please verify the correct type prior to ordering if that is what you wish to do.) You can certainly order from a Mercury dealer or online Mercury parts distributor.

https://www.iboats.com/mall/partfinder/?cart_id=074474413&gd_grid_id=1284&gd_poid=111811&gd_row=8&session_id=074989325

Now I will tell you that I have only repaired Evinrude/Johnson motors and I am not a mechanic, but the concepts are the same. I replace a powerpack/switch box on my 1978 Evinrude 55hp a couple of years back because it all of sudden ran at half power and idled rough and it was easy enough to replace the powerack. Just look at the replacement part and compare to your current one and use a digital camera to help remember where the wires connect.

Oh by the way 85lbs of pressure on cylinder for 6hp is fine and certainly within 10% of each other.

Good luck my friend,

cajuncook1

 

[irishfan]

I will probably do the work myself. A switchbox is pretty simple. I can order a needle and seat, carb kit and the switchbox for less than the repair shop would charge me for just a switchbox. Paid them $25 just to verify it was the switchbox and do a compression test. Cheaper than buying a switchbox only to find out I was wrong!!!!

 

[Johnny5]

How do you KNOW its the power pack, has someone checked the output voltage from the said pack to the coil, and it could be one side of the stator not putting out the voltage to the pack (stator and packs usually go out because of years of slight overheating) get a volt meter and poke around a little, trace wires and check both sides to see if the volts match

 

[irishfan]

How do you KNOW its the power pack, has someone checked the output voltage from the said pack to the coil, and it could be one side of the stator not putting out the voltage to the pack (stator and packs usually go out because of years of slight overheating) get a volt meter and poke around a little, trace wires and check both sides to see if the volts match

I checked the stator and the trigger myself. Switched wires to the coils and the problem moved. Took it to the local repair shop. They did a compression check and used the DVA on it to verify my findings Like I said, paying someone $25 to find out for sure is cheaper than buying the pack and finding out I was wrong. :mrgreen:

 

[Johnny5]

Its always cool tinkering and learning stuff then having a pro verify you were right in your findings, The trick is knowing how to be humble when your wrong Glad you got it figured out though. tight lines!