120hp Force won't idle

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bbassett

Cadet
Joined
Sep 9, 2009
Messages
20
I have a 1994 120 hp Force outboard. Had the stator go out on it last fall and was not able to fix it until this spring and so the boat was not winterized like I normally do. Had 1/4 tank of fuel which I put Stabil in for the winter.

I replaced the stator and filled with fuel. Not sure if this is relavant or not but also had the controller and cables replaced this spring. I also ran the decarb process I found on this website using Seafoam.

Boat will not idle below 1000-1100 rpm without shutting off.

Any ideas what could be going wrong?
 
further

further

Lieutenant Junior Grade
Joined
Jun 18, 2009
Messages
1,031
Re: 120hp Force won't idle

idle rpm should be around 1000-1100. 700-800 in forward gear.
 
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buckarrow

Cadet
Joined
Jul 5, 2010
Messages
16
Re: 120hp Force won't idle

I had this same problem. How do you change the idle speed? I know there is a screw on my carburetor for idle/mixture, but I wasn't sure if that had a different use.
 
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bbassett

Cadet
Joined
Sep 9, 2009
Messages
20
Re: 120hp Force won't idle

Thanks for the info. I will reset the idle to 1000-1100 and see what the idle is in forward.
 
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bbassett

Cadet
Joined
Sep 9, 2009
Messages
20
Re: 120hp Force won't idle

I brought the boat out to the landing today (left on trailer with motor in water). Motor started well and idled at 1100 rpm. I let the motor warm up. When shifting it into forward, the engine died. If I shift very fast, it will stay running but I need to do quickly and get rpms above 1000. If I then slowly reduce rpms, as soon as the boat gets below 1000, it either dies or drops to 200-300 and runs roughly. If it is continuing to run and I do not touch the throttle, the rpms will slowly increase to about 600-700 rpm at which time it seems to clear inself out and jumps to over 1000 rpm.

I have changed the fuel filter, put new plugs in, have spark on all 4 cylinders, and fuel bulb is solid.

Any ideas what is going on?
 
J

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: 120hp Force won't idle

Your timing may be a bit off. If the throttle plates open without an advance in timing, the engine will usually die. You say you had your cables replaced. If they didn't rig the cables correctly, that may be your problem.

The best thing to do with Force timing issues is to get the book out and start from the bottom. If the throttle cable, carbs, and timing tower are not set properly, getting these engines to run right is impossible.

John
 
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bbassett

Cadet
Joined
Sep 9, 2009
Messages
20
Re: 120hp Force won't idle

Update: I brought the boat back to who did the controller install. They checked it over and determined the spark on 2 cylinders was weak at low rpms. Ended up replacing switch box - which they said they do quite a few of a year. This solved the issue.

I asked about how they knew it was the switch box. Said that there is really no test but they test everything else and if nothing else is wrong, the switch box must be.
 
S

shane01101

Cadet
Joined
Jul 12, 2010
Messages
17
Re: 120hp Force won't idle

how much did that cost you? Im curious because I have a 1990 120HP Force and I was having these issues last year but now I do not anymore
 
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Behoppe2

Recruit
Joined
May 17, 2009
Messages
1
Re: 120hp Force won't idle

Hi,

I have a 91 Bayliner Capri with a 120 HP L-drive. I have had the same problem with the idle and I discovered that the problem is mostly the battery.
The Force motor runs on the battery when idleing. It can not produce enough amps from the stater under 1500 rpms. Charge your battery and check if it is has enough amps. This is also a problem that happens to Force boaters who pull skiers or tubes. Lots of stopping and starting on the water and then not enough juice to idle back in to the docks.
 
J

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: 120hp Force won't idle

The problem of low alternator output is easily and inexpensively corrected by installing the Universal Regulator. The regulator allows for charging at lower rpms and batteries last longer as it regulates the voltage to 14.5 volts to avoid warping the plates and boiling off water.

John
 
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PaulO

Petty Officer 1st Class
Joined
Jan 25, 2010
Messages
225
Re: 120hp Force won't idle

Try idling with the engine cover off. I found with my 120 The carbon monoxide was filtering into the engine bay past the lower leg rubber seal as it was starting to split in the back corner. It was fine with the cover off but would soon die at idle with the cover on. once the boat was moving the carbon monoxide was being drawn away from the leg and wasn't an issue.
 
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