1988 25hp

[joho5]

couple question.

1. how does the spark plugs work on this motor? It is the kind with no shank. NGK makes them. How does it fire?

2. this is my dads motor and it lately has been in consistent. We think it was running on 1 cylinder because it was running with no power and sluggish. Every once in a while it would kick up and run full out. It would just be all of a sudden. Could this be a the or a coil(s)?

reason I ask is because we took the coil cover off and they just basically fell apart. They were cracked and when we lifted them out of there they broke in a few pieces.

Does that sound relative to the conditions?

thanks

 

[Laddies]

Re: 1988 25hp

Changing the broken coils would be a good place to start, if that don't correct the problem get back and we will give you a ign. system test.

 

[OldMercsRule]

Re: 1988 25hp

couple question.

1. how does the spark plugs work on this motor? It is the kind with no shank. NGK makes them. How does it fire?


Joho I have three Merc 25s, I am still puzzeled about the third one and maybe we can help each other. The third one is the oldest the other two are 1996 and 1989. I bought the third one second hand and it had "surface gap plugs" in it which ran fine, the NGK web site shows the correct plug fer all 25 two stroke Mercs from 1980 on to present is BP8H-N-10 @ .40 Gap, (a cornventional plug with an air gap), the 20HP Mercs prior to this engine (1979 back) used surface gap plugs.

2. this is my dads motor and it lately has been in consistent. We think it was running on 1 cylinder because it was running with no power and sluggish. Every once in a while it would kick up and run full out. It would just be all of a sudden. Could this be a the or a coil(s)?

Yep.

reason I ask is because we took the coil cover off and they just basically fell apart. They were cracked and when we lifted them out of there they broke in a few pieces.

Does that sound relative to the conditions?

thanks

The engine I'm telling you about ran fine first on the surface gap plugs and subsequently on the air gap plugs I mentioned that I put in. I then lost the switch box which killed the lower cylinder. So I need to get a new one and replace it when I get back up there.

Does your Dad's 1988 have a round choke knob that you turn to increase cold start engine speed or a square choke with three positions?

Thanks. JR