87 9.9hp fuel pump problem maybe

[steve83073]

I have a 87 mercury 9.9hp when I give it full throttle it chokes itself out it seems but a half it runs but not like it should. I'm not sure what the problem is I think it might be the diaphram in the fuel pump but I'm not sure. And every now and the it will run at full throttle but will bog down after a bit. Can anyone tell me if they have ever heard or seen this problem I'd be forever greatful.

 

[mpinkstone]

Re: 87 9.9hp fuel pump problem maybe

Yea, I'm having the same problem with my 9.9HP too. Idles fine, starts great, and runs low to mid RPM great, but when you try to go any further it falls on it's face. I think I narrow mine down to the SWITCH BOX. When I spray the SWITCH BOX with a can of freeze it revs right up only to sputter again. I will know for sure when I get my new SWITCH BOX. Do a search on MERCURY 9.9HP WON'T ACCELERATE, to see my post, and if I find anything out I will under my post.
GOOD LUCK.