1994 force 120 stalling issue

SteveinVA

Petty Officer 2nd Class
Joined
Dec 16, 2010
Messages
106
Ok done some research already. Found simiiar issues but no fixes. Motor runs on hose and in water with cowl off. Cowl goes on and it stalls shortly after. I have read exhaust leak but I dont know where to look. Also you would figure the inside of the cowl would get full of fumes and exhaust but mine doesnt smell at all? I have looked around the motor while it was running and nothing looked to be leaking exhaust wise. Im flabbergasted. Gonna have to get learnt up on these motors.... BTW new impeller and housing installed by myself.. you ever hear of a shop installing a new impeller into a cracked housing? Me either till I bought this boat. The PO had it done before I bought it. I actually picked it up at the shop afterward...I was always a DIY guy and that just adds to the case. Anyway any help would be greatly appreciated it.
Thanks
 

pnwboat

Rear Admiral
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Oct 8, 2007
Messages
4,251
Re: 1994 force 120 stalling issue

If it is an exhaust leak, it's usually item #27 the rubber boot in the diagram below. You have to remove the lower cover #22. 8 bolts go in horizontally that hold it to the lower leg, and 6 more bolts that go in vertically that hold it to the cowling. You have to take the cover off to access the 6 bolts.

Mercury, Mercruiser, Force, etc. - DRIVESHAFT HOUSING - 120 H.P.
 

MickLovin

Master Chief Petty Officer
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Feb 18, 2013
Messages
822
Re: 1994 force 120 stalling issue

Make sure there is nothing coming into contact with the air intake of the carbies when the cowl goes on, I have heard of foam on the cowl housing causing this.
 

SteveinVA

Petty Officer 2nd Class
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Dec 16, 2010
Messages
106
Re: 1994 force 120 stalling issue

Thanks guys, as far as the rubber boot goes I replaced it this winter along with items 26, 28 and 29. I had the motor off this winter, pulled the entire lower unit, replace items mentioned above and the impeller housing. As far as the foam I have reglued all the foam on the inside of the cowling, non of it is loose. I have been working on this since last fall, still doing the same thing as before?? Where else could the exhaust be leaking from?
 

jerryjerry05

Supreme Mariner
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May 7, 2008
Messages
17,923
Re: 1994 force 120 stalling issue

On the parts diagram right where the #1 is shown on the diagram is where a lot of motors leak exhaust.
Underneath the power head is a part called a spacer there's a gasket there it will leak in the same area.
Fill a squirt bottle with 50/50 gas and TCW-3
Use it to spay into the carb as you run it.
The idea is to make it smoke as much as you can.
Remove the cover.
Make it smoke.
Look for the exhaust.
My motors are 26 this year.
Last year the port one started doing the same thing.
The clamp on the rubber exhaust boot was rusted through and would leak exhaust.
I checked the other motor and it was bad too, just not leaking.
 

SteveinVA

Petty Officer 2nd Class
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Dec 16, 2010
Messages
106
Re: 1994 force 120 stalling issue

I'll give it a shot this evening. Could I just disconnect the fuel line at the hull and run into a bottle with the same mix?
Thanks Jerryjerry05
 

SteveinVA

Petty Officer 2nd Class
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Dec 16, 2010
Messages
106
Re: 1994 force 120 stalling issue

# 30 is definitely not in the best shape. I've pulled it out, one side is smashed up. Its in now, just not a tight fit. I figured that was just to keep water from riding up. I've looked around for a replacement but couldn't find one available.
 

Jiggz

Captain
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Oct 23, 2009
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Re: 1994 force 120 stalling issue

The smoke test sounds promising. Use a flashlight to have a better look at the smoke source.
 

SteveinVA

Petty Officer 2nd Class
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Dec 16, 2010
Messages
106
Re: 1994 force 120 stalling issue

On a plus note, I've also got water in my lower unit,... SO things are looking up:facepalm:
 

MickLovin

Master Chief Petty Officer
Joined
Feb 18, 2013
Messages
822
Re: 1994 force 120 stalling issue

Hopefully it is only a driveshaft seal you need to replace look for just that part first, it may be cheaper than all those seals which you may not need.
 

jpwilly

Petty Officer 3rd Class
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Jun 15, 2011
Messages
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Re: 1994 force 120 stalling issue

Yip looks like an (pretty bad) exhaust leak.
 

Jiggz

Captain
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Oct 23, 2009
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Re: 1994 force 120 stalling issue

Personally, I will remove the mid-leg cover and do the test again. Remember, exhaust normally exits the two nostrils where the rubber boot connects. With the cover removed, keep the boot in place (with hose clamp) just to make sure the exhaust comes out of the end of the rubber boot and not somewhere else.
 

SteveinVA

Petty Officer 2nd Class
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Re: 1994 force 120 stalling issue

My plan right now is to remove the lower unit and do a compression test @10 psi and look and listen for air leaks. Then order the seals I need. I just looked back through all my receipts and I had ordered a new gear cover housing w/gasket and all the Orings and everything that goes below the water pump, fairly certain the leak is from around the prop shaft area.. Thanks
 
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SteveinVA

Petty Officer 2nd Class
Joined
Dec 16, 2010
Messages
106
Re: 1994 force 120 stalling issue

On to the exhaust issue. I've searched and searched and cannot find anywhere that sells #30 motor leg, seal. So next course as stated by Jiggz is I am gonna remove the mid leg cover and see if I can find anything. Anyone else please watch the video and let me know what you think, I am open to all suggestions.
thanks
 

SteveinVA

Petty Officer 2nd Class
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Dec 16, 2010
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Re: 1994 force 120 stalling issue

I think food fisher may be right. I took the lower leg rear cover off yesterday and ran it. Fanning the smoke away and looking around the exhaust area I didnt see or feel anything. I am running a little rich on my mixture causing excess smoke and with a faulty lower leg housing gasket the smoke gets pulled right up into the cowl. The only other place it could be coming from is directly under the carbs but from looking at the diagrams the exhaust doesnt go through that area??
So anyone ever dealt with the lower leg housing gasket issue,?
 

MickLovin

Master Chief Petty Officer
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Re: 1994 force 120 stalling issue

Ok part # 30 is more about stopping water coming up into the cowled area and splashing around under your spark plugs, it would be part number 1 or 17 , and from what I have heard about the Chryslers it had a similar problem with part number 1 and I came across it on my 1976 75hp Chrysler and on my 12.9 chrysler, with exhaust on the 75hp not entering into the cowl so much but on the 12.9 it would choke it to death. If you pump carbon monoxide into a small area it will take over the oxygen level into the carbies and kill the motor due to reduced combustion.
The reason you didn't feel anything is because the leak could be around the front like my 12.9 which is just under the head. As I was saying before about the seal kit, hopefully it is only the driveshaft seal, but as jerry jerry suggested do a pressure test, but make sure you know what pressure to put in there first. I have had drive-shaft seals go twice.
Just my 2 cents worth.
 
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