mercury 25- What Next???

[commonarcwelder]

I have a mercury 25 that quit in the water and would not start back up. Cleaned the carb. and entire fuel system. New hose and tank with fresh gas and oil. Starts up and runs but real bad. Will not smooth out in any RPM. Pulled both kill switch wires thinking one maybe grounding.....didnt cure the problem. Could this be a powerpack? Carburetor is clean; all circuits check out. What ya'll think? Before I sink the money in this thing.

 

[8075mercury]

Re: mercury 25- What Next???

Not sure what year you have, but I think the 25hp Mercury is a good motor.

My thoughts (some of this you may have done already)
*Get a factory manual, check ebay
*Check the compression, needs to be 100+psi
*I assume you are getting good spark on both plugs
*Make sure the carb float setting is correct and the fuel diaphram does not have pin holes.
*Check out the coils, trigger and stator with an ohm meter. Also make sure your coil wires are grounded well along with checking with the rest of the wiring for good connections and good insulation. Also make sure the trigger advance mechanism is working well.
*Check the small hoses that contact various parts of the powerhead for deterioration and thus leaks.
*Check the reeds by pulling off the carb and putting your hand over the carb opening. It should pressure and suck and you spin the flywheel.
*If all of above checks, I would guess the switchbox is highly suspect. I do not know of a good way to test the switchbox unless you have expensive test equipment.

Hope this helps. If you decide you do not want to fool with it, I might be interested in buying since I live in Opelousas.

Good luck.

 

[commonarcwelder]

Re: mercury 25- What Next???

Its a 2000 model.....Just replaced both coils with two known good coils. Same crap....Replaced carb. with a known good carb off a 98...Same crap. The 98' has a different pack though. Don't have a donor pack.

 

[commonarcwelder]

Re: mercury 25- What Next???

Is there any way to test the powerpack? Can the dealer do this? Thanks for the reply there 8075MERC.

 

[8075mercury]

Re: mercury 25- What Next???

If you went through all of the list above and everything checks out good per spec and you still have the problem, I would guess the switchbox. I looked in a factory service manual just now and if you only have conventional tools, like ohm meter, then you can use the process of elimination to rule out everything else but the switchbox. There is and a dealer should have the special meter to test the switchbox. However, I would compare the cost of getting the switchbox tested vrs just buying a new switchbox. I would check around on the internet or call Kenyon Power Boats in Fla.
Good luck.

 

[Laddies]

Re: mercury 25- What Next???

Before we can give you help on the test for the ign system we need the serial number or number off the switch box.

 

[commonarcwelder]

Re: mercury 25- What Next???

Before we can give you help on the test for the ign system we need the serial number or number off the switch box.

Ok.....I found a number - 855713... Thanks alot guys. I've got Mercury on the brain....was at work all day thinking about it. I know it is something in the ignition. Thanks again!!!

 

[Laddies]

Re: mercury 25- What Next???

Keith, this should be the test for your engine from CDI

 

[8075mercury]

Re: mercury 25- What Next???

Super good info ! Thanks !!

question:
DVA output is the same as DC volts, correct?

 

[Laddies]

Re: mercury 25- What Next???

No, DVA volts are AC volts captured with a peak voltage meter or DVA

 

[commonarcwelder]

Re: mercury 25- What Next???

Laddies, I do appreciate the info. I will test in the next few days and let ya' know what I find. Got home from work earlier and my wife and 5 year old both have strepth throat so I'll be fixing them. Thanks again....

 

[8075mercury]

Re: mercury 25- What Next???

Thanks for the explaination of DVA

 

[commonarcwelder]

Re: mercury 25- What Next???

Well switch box didn't check out. Ordered one yesterday. Will let ya'll know the results..... Thanks for the help!!!

 

[commonarcwelder]

Re: mercury 25- What Next???

Got the switchbox replaced today finally. It will idle now but it misses and backfires. Runs this way up until about 1/3 throttle. Any suggestions? Tried another carb off a known good running motor along with both coils. Thanks for the help!

 

[Laddies]

Re: mercury 25- What Next???

If the plugs and coils are good, I would pull the carb and manifoil cover and chech the reeds a chipped or cocked reed will chirp through the carb but at speed the engine will run well

 

[commonarcwelder]

Re: mercury 25- What Next???

Thanks for the reply. Gonna go pull it now. I was kinda' veering away from that idea being that there is no gas or air being exhaled out the carb. while running. I'm picking at straws now though.

 

[commonarcwelder]

Re: mercury 25- What Next???

Ok. I pulled the intake manifold and the reed cage. All the leafs look new. No spaces. I'm at a total loss. Whats most likely to go out; pickup coil or statorr?

 

[Laddies]

Re: mercury 25- What Next???

Keith, of the two I would pick the stator as it is two windings a high and low speed and the trigger is a single with a feed to the swich box off both ends. When you remove the flywheel check the magnet very closly for cracks or being loose they can give a person fits and this one is one of those deals Bob

 

[commonarcwelder]

Re: mercury 25- What Next???

Thanks Bob. I'm gonna just order a stator and see. Kinda' makes sense i guess. At low speed it misses and backfires. I've covered all bases; literally. Even though it tests out good; maybe it has a break somewhere that only effects it during vibration or at a higher voltage?? Thanks again!

 

[commonarcwelder]

Re: mercury 25- What Next???

I went out to the shop and inspected all ignition parts very carefully. On the pickup coil; the plastic around the epoxy (or whatever it is) is separated. Is this normal? It's maybe a 1/64". If that. I can open it up a little with my fingernail. I know I have seen them like that before from age. Think I should order a trigger as well as a stator? Thanks, Keith