Force 120 hp Exhaust seal

Hi Guys
I am really hoping someone can help me, I recently upgraded to a Force 120hp motor and have been having problems getting it going properly. When I run it out of the water on muffs it runs lovely, as soon as I put it in the water it does start but cuts of after a few seconds. It will only stay running on the water if the cowl is removed. Now this baffled the hell out of me for some time and after a few pain staking trips to the water (40 minutes away) and not being able to get it to work i took it to a local repair place who diagnosed that it was an exhaust problem and that the exhaust fumes where not coming out of the exhaust and prop as they should but coming up in the motor and so choking the carbs causing it to cut out. they also said I have a worn or missing seal in the exhaust which was causing the problem. After alot of investigating I have found the seal that I should have which is not on my motor(thanks to the lovely chap who sold it to me!)My question is this is this correct? and if so does anyone have any idea where I can get one of these seals? The link below shows the seal it is item 93 on the top right corner of the diagram.

http://www.boats.net/parts/search/M...992 L-DRIVE)/120LD92B/GEAR HOUSING/parts.html

Any input will be most appreciated guys

Not sure that's your problem???
Usually if it chokes itself out the seal under the powerhead is bad or the exhaust rubber boot is misaligned or bad.
The seal is just silicone.There is a gasket between the head and spacer plate.
Start it in the drive and check for exhaust comming from under the head.

If it really is that seal.Just fill it with silicone and shape it in place.

Thanks for your input Jerry much appreciated, not sure the bits you are talking about are but does anyone know a mechanic in Poole or Bournemouth that can sort it out for me without tearing a big hole in my pocket?
Or perhaps a diagram of the bits I need to check if it's not to far into the motor.

The bits are under the cover.
They are at the base of the powerhead.
The link you posted was for an L-drive.
You need to find the right motor(unless you have an L-drive).
They made 3 drives for that motor all basically the same.

http://www.boats.net/parts/search/Merc/Force/1992/H1201A92A/parts.htmlThis is for your drive,
http://www.boats.net/parts/search/Merc/Force/1992/H1201F92F/parts.html #45,46 it's possible it leaks there.

http://www.boats.net/parts/search/Merc/Force/1992/H1201F92F/parts.html #27 there too.


Not sure of any repair shops in that area

There should be a rubber "boot" connecting the exhaust manifold to the two little holes on the back of the leg housing. Mine says "Power Flow Exhaust" or something silly. Anyway, my boot split, and did exactly what you are talking about. If the exhaust is going into your cowl area, there is no oxygen for the carbs to use. I ordered one online, eezy shmeezy.