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1995 Force 120 Hp OB idle issue

xtrip

New member
Hello,

I recently purchased a bayliner capri 1700 ls with an 1995 Force 120 hp outboard motor. I know..some say "friends dont let friends buy bayliners.." Its my first boat ever and i didnt know much about outboard and marine engines. Im an engineer and somehow mechanically inclined..and i wished i did a bit more research before buying the boat but..long story short now im stuck with it and trying to make the best out of it.

The boat runs great, it reaches about 40 mph at 5500 rpm and the only real problem was the idle..i'm be able to start it only with the throttle pressed about half way (even when is warmed up , not sure if this is the norm or should start with just the shock- key pressed) and then even when it warms up it would die shortly after being in neutral, it idles around 600 rpms. I knew this is very low and the potential cause of the issue..so i took it to a friend that used to be a marine mechanic for a long time but never worked on a force engine. He cleaned the carbs, adjusted idle..speed, carburetor and with a water hose attached it would idle at 1200. Great! i left for vacation and brought the boat with me.. ..it started very easy first time ..but after a few minutes running, the idle fell to around 600 rpms and it would die in neutral - it would take me 3-4 attempts to get it in gear from neutral. Unfortunately, I dont have access to my mechanic friend again..and would like to try to fix it myself...he had advised me the timing and carburetors are all set and if the idle is not running as it should in the water, i should just try to adjust the timing rod (screw next to flywheel)..I did that and after a few turns (clockwise) i managed to have it running at around 1000 rpms. At this point it would start right away..no need to accelerate in neutral. I ran the boat and minutes later again, idle fell again to 600 rpms, and same story..it would not start without acceleration. I noticed the nut holding the screw it would move towards the center of the screw..so probably from the vibration the screw would not keep its position. I attached the picture..with the screw ..after the adjustment I would find the nut to where the green mark is. So my question is..should I tighten the nut with a wrench while keeping the screw in the same position? Am I missing a spring there that should keep the pressure on the screw and prevent the nut moving? is the nut in the right position ?

Force2.jpgForce1.jpg

I havent done a compression test yet..mostly cause of the fear of very bad news
smile.gif
(spent all my savings on this boat)..but i keep thinking if the boat reaches 40mph and works well most of the time, compression its not an issue.

Another question i have should i use Seafoam motor treatment? if yes, should i use this all the time or just one - two tanks of gas?


thank you all for reading and i appreciate any advise you guys can give me.
 
" So my question is..should I tighten the nut with a wrench while keeping the screw in the same position?" YES Even a bit of Loctite.

" Am I missing a spring there that should keep the pressure on the screw and prevent the nut moving? "NO
"is the nut in the right position ?"YES

Adjusting the timing to step up the rpm's could cause engine failure.

The towershaft is where you adjust the rpm's.

https://www.youtube.com/watch?v=tDoR64jP5l8&feature=youtu.be
Watch this video
it might help??
http://forums.iboats.com/forum/engi...orce-chrysler-faq-and-other-great-information
This might help too.

Get a factory manual. That can answer a lot of questions too.

Do a comp test.
Seafoam is useless(my opinion) If you need a carbon remover use Mercury's Powertune or OMC's Engine Tuner.
Or add Chevrons Fuel Injector cleaner. It has Techron, black bottle. Mix it in 1 gal of gas and add proper TCW3oil.
Then run it through the fuel system.
 
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thanks a lot Jerry. I watched the videos several times and also print it out the guide..I looked trough the whole internet for a service manual but all i could find was a Seloc manual, thats not very helpfull.
I realize the risk for doing these kind of adjustments without proper knowledge and i decided to take it to a mechanic..near my place. He hesitated to work on it..since its a Force..engine, arguing parts are hard to come by but in the end he accepted ..He did a compression test, results are:

Cyl 1: 125
Cyl 2: 125
Cyl 3: 150
Cyl4: 150

Are these numbers worrying? Do they say anything about the life left in the engine..before it needs a rebuilt? The boat drives pretty well and i reached speeds of abt 40mph with a 4 blade prop, with a 3 blad would probably go faster
I found a service bulletin where out of the factory this engine had a difference in compression: http://www.marinemechanic.com/merc/d...essiontest.PDF
 
If your gonna keep this get a factory manual.
Any Merc. dealer can get the one you need.

The comp is in range.
They made the motor with the different comp on purpose.

Get a can of Mercury's Power Tune or OMC's Engine Tuner.
Follow the instructions and after running a while do another comp test.
The results will probably be the same.

Where are you located?
 
If your gonna keep this get a factory manual.
Any Merc. dealer can get the one you need.

The comp is in range.
They made the motor with the different comp on purpose.

Get a can of Mercury's Power Tune or OMC's Engine Tuner.
Follow the instructions and after running a while do another comp test.
The results will probably be the same.

Where are you located?

thanks Jerry

Im located in Montreal, Canada...Unfortunately so far i havent been able to find a reliable mechanic, most of them refused to even look at the engine..because its a FORCE. In the end i found one who accepted ..i specifically asked him to reset the carbs and do the timing and i went to pick up the boat today the timing..was exactly in the same position. He said.the engine works very well..and therre was no other way to adjust the idle other than changing the timing!?!?..i asked him..if he has a timing light he said..he doesnt need one..go figure..what a mechanic, total waste of money and time.

In the end i decided to follow the tutorial and Frank video and do it myself. One thing im not clear though..in adjusting timing, to achive WOT , static..does it have to be in gear? if not, can i use the boat controls or i have to remove the cables and just accelerate using the cam?

Also, i understand when checking timing i have to ground the spark plugs wire and the timing light i have to attach it to the cyl 2 coil: i saw a video on youtube for ajusting where the guy left the cyl 1 spark plug and wire in place, so my question is do i have to ground the cyl 1 wire too and then attache the timing light clamp to it?

Thanks so much!
 
tester2.jpgtester.jpg
http://www.boats.net/parts/search/Merc/Force/parts.html Look for towershaft.
#4
Pull all plugs.
Ground the wires(see pic, that's what I made up to ground the cyl.)
Key on, shifter all the way forward in gear.
Some remove the prop for safety.
Timing light on #1.
Then I use a jump box or jump wire.
Then in the front above the carbs is the timing mark.
Battery HOT!!! and a charger attached(helps it spin but not necessary)

Turn over and see where the timing light aligns with the marks.
Make sure the marks are visible. I use tiny strips of white tape or white polish.

The idiot who said he didn't need a timing light is just that.
You can preset the timing without the light but you can be off as much as 10d.

On the 95/120 you still adjust the throttle/idle with the towershaft.

Go get your $$$$ back from the mechanic. He'll think he's right and screw up someone else.
 
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View attachment 12084View attachment 12085
http://www.boats.net/parts/search/Merc/Force/parts.html Look for towershaft.
#4
Pull all plugs.
Ground the wires(see pic, that's what I made up to ground the cyl.)
Key on, shifter all the way forward in gear.
Some remove the prop for safety.
Timing light on #1.
Then I use a jump box or jump wire.
Then in the front above the carbs is the timing mark.
Battery HOT!!! and a charger attached(helps it spin but not necessary)

Turn over and see where the timing light aligns with the marks.
Make sure the marks are visible. I use tiny strips of white tape or white polish.

The idiot who said he didn't need a timing light is just that.
You can preset the timing without the light but you can be off as much as 10d.

On the 95/120 you still adjust the throttle/idle with the towershaft.

Go get your $$$$ back from the mechanic. He'll think he's right and screw up someone else.


THANKS SO MUCH JERRY!

Im planning to do this..the coming week-end. One last question..any advice on how exactly i could locate the neutral switch box? Also, im a bit confused abt the exact timing number. I read on some posts that should be at 28 degrees, others at 30. My engine is 1995 120 HP and even though i called the local marina (merc dealer) they couldn't locate me a manual. Fortunately, there is one for sale on ebay...very expensive though - 130$ ..and they have a photo from the manual of the exact timing page:

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Not sure how to translate "maximum timing at 5000 Rpm: 30d BDTC "..should it be 30 degrees when doing static timing or anything less than 30 would be good?
 

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Here I also have a picture of the side engine..to help maybe identify the neutral switch box:
 

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830565 That's the part# for the manual.

Look around you can find manuals on CD for cheap.

You use 32d 28 is for the older Forces.
Mercury installed their electronics and it changed to 32d.

The neutral safety is probably in the shifter.

A pic inside the cowl under the fuel pump will show the old style switch if it's there.

You won't need the switch if you use a jumper at the solenoid.
Just turn the key on and it will energize the system.

Send me a pm with your e-mail if you have any questions.
I only get on here in the morning and don't always get here.
 
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