1992 Force 120 rough idle, exhaust issue

[Waltk]

I have a 1992 Force 120 that was stalling out when I put it into neutral or when I was pulling into the dock and tried to shift into reverse. I initially had both carbs rebuilt, which helped but did not fix the problem. It runs great wide open, only have the problem when I am at idle or slow speeds.
Thanks to other posts, I was able to troubleshoot the problem to a bad exhaust seal in the lower unit. The part number is F698735-1 but it is a discontinued item and I am having all kinds of problems finding a replacement part. The exhaust is filling up the cowling cover and choking out the carbs. I took the cover off and noticed the smoke coming up from the bottom of the engine. With the cover off, I have no stalling or rough idle issues.
My question is this, has anyone ever installed a blower into the cowling cover? If I cant find the part, I have to do something and my thought process was to put a small blower into the back of the cowling cover with some vents on the front. The concept is to draw out the exhaust fumes that are choking out the carbs.
Has anybody ever done this or heard of anyone who has? Would it cause more problems or would it help.

 

[jerryjerry05]

Re: 1992 Force 120 rough idle, exhaust issue

Post a pic of that part. It's possible there is a fix?
You might be able to fill the cavity with sillycone???
Yes you probably can rig something, possibly block the fumes off with foam rubber in the lower casing?
Blocking off the exhaust? Even putting a manifold on the carbs?
With a bit of jury rigging anything can be done??
Fill out the profile, location? You might be close to someone who can help?

 

[Capt. Steelhead]

Re: 1992 Force 120 rough idle, exhaust issue

I've been fighting this demon for awhile I decided on painting the the boat and dealing with it later well guess what I'm done painting. I have a '91 120 and it idles great at a 1000 rpm's but put the cowling on a just like you said it starves for fresh air. I was thinking of spray foam to tighten that gap between the rear cover and the main part that ties the lower unit it looks like a vibration seal but I can see right through it. For the fan idea, computer fans are 12v just a thought Something isn't right I rebuilt this motor it runs great once it leaves the dock but it is un-nerving when you don't trust it with the cowling on at the dock.

 

[foodfisher]

Re: 1992 Force 120 rough idle, exhaust issue

The part is NLA for me also. I just put the hose there without it. Works fine.

 

[Jiggz]

Re: 1992 Force 120 rough idle, exhaust issue

A pic will be very helpful.

 

[Capt. Steelhead]

Re: 1992 Force 120 rough idle, exhaust issue

If you have a fix that's great but I'm not understanding your solution please explain thanks, Paul

 

[jerryjerry05]

Re: 1992 Force 120 rough idle, exhaust issue

He posted and never came back.
Must have fixed his problem??
I was having the same problem.Both motors.
Turns out the exhaust bellows clamp was rusted and part of it was broken and letting gasses in the cowl.
I replaced with stainless clamps and problem solved.
No more stalling at the dock.

 

[Capt. Steelhead]

Re: 1992 Force 120 rough idle, exhaust issue

Yeah my clamps rusted to but it still works still good enough to seal in fact it's pretty tough to remove. The smokes coming from lower than that, I can watch it bubble up through the water inside the back cover. Thanks, Paul