1997 Force 120 gone wild

[maildude1960]

Starting out, it would not idle and had very little power. Pulled the carbs and reed plates off and found it had a broken reed. Replaced the block, put it all together and now it idles very erraticly and very high (2000-3000 rpm) and spits and sputters. Sounds like your gunning a chainsaw. I pulled the carbs again and soaked them. Still the same. You can cover the top carb, little change, cover the bottom carb, immediately dies. Pulling the bottom 2 plug wires slows it down. Also turns over very slow with fully charged battery and seems to smoke heavily. Please help!

 

[john from md]

Re: 1997 Force 120 gone wild

Pull the fuel pump and check the diaphram. It may have been damaged if the engine backfired from the broken reed.

John

 

[Robert D]

Re: 1997 Force 120 gone wild

Did you readjust the mixture and idle speed after replacing the reeds? It was probably adjusted with the bad reed, and now that's taken care of it needs to be readjusted.

 

[pnwboat]

Re: 1997 Force 120 gone wild

Sounds like something is way out of adjustment or you have a vacuum leak around the upper carb. or reed block assy. Make sure you have a gasket both under and on top of the reed block assy. Items 9 & 12 in the diagram below.


http://www.boats.net/parts/search/Merc2/Force/120%20H.P.%20%281997%29/0E203000%20THRU%200E287999/Reed%20Plate%20And%20Primer/parts.html



Also make sure you have the correct type of reed petals. Starting around 1995 or 1996 and later, the reed petals themselves had squared off ends. Earlier reed petals had rounded ends.

If all that checks out, check the compression in the cylinders that are fed by the reed block that was replaced.

 

[moparman]

Re: 1997 Force 120 gone wild

have you run a compression check on it after ingesting the broken reeds???It might have a compression issue after all that its been through. Check it and post the results. MOPARMAN. ROLL TIDE

 

[maildude1960]

Re: 1997 Force 120 gone wild

Thanks for all the replies. Right after my first post, we got a new pastor at church and I am in charge of renovating the parsonage that has been empty for 3 years. Needless to say, I have been VERY busy since then and completely forgot I had even posted on here. I will check the things you guys suggested and let you know.

 

[kend301]

Re: 1997 Force 120 gone wild

Sounds like you have the upper reed block in upsidesdown . If this is not the case check the reed block and be sure the reed travel is as specified in the manual.

 

[maildude1960]

Re: 1997 Force 120 gone wild

Still fighting this problem. Took some vacation time so I have a little time to work on it. I rebuilt the fuel pump, no change. Checked the compression (cold) #1 read 130, 2 read 150, 3 read 150, 4 read 160. Rechecked #1 and it read 145 the second time. Checked timing, it was ok. My neighbor thinks it may be a broken ring or piston on #1, but I can find no evidence of that except for the lower compression, no debris, etc. All 4 spark plugs have oil residue like maybe they're not hot enough. Crappie season is here and I need to get this fixed!

 

[maildude1960]

Re: 1997 Force 120 gone wild

Replaced the top crankshaft seal on the advice of a mechanic. Also found 2 check valves in the recirc system that were not check valves anymore, but straight thru fittings, and replaced them. Cranked it up and it idled normally for about a minute and then it was off to the races. Anybody have any thoughts on this?

 

[pnwboat]

Re: 1997 Force 120 gone wild

When you say "off to the races" are you saying it still does not run right?

 

[john from md]

Re: 1997 Force 120 gone wild

With all you have done to it, I do not read anywhere that you have checked the carb/timing syncronization. Your timing can be right on but if the carbs are not sync'd right, the engine won't run right.

To sync these engines, you have to start from the beginning and do each step. If you don't, you will have no base line reference and it won't come out right. Both the Clymer and Seloc manuals have the procedures.

I'd say give it a try as there isn't much left.

John

 

[maildude1960]

Re: 1997 Force 120 gone wild

Sorry, "off to the races" meant it started idling out of control again.

 

[maildude1960]

Re: 1997 Force 120 gone wild

You are correct John, I have not done the sync procedure. I will do this tomorrow. One thing I notice right off the bat is the manual shows the throttle cam flush up against the roller on the carb. Mine is 1/4" away from it at idle.

 

[maildude1960]

Re: 1997 Force 120 gone wild

Okay, went thru the sync procedure and it helped tremendously. Enough that I'm not afraid to put it on the water and make final adjustments. The reason I never went through all the linkage adjustments was because they have never been messed with since it was new. My tachometer doesn't work, so I can only guess how fast it is idling now. Any ideas on what to look for there? I know its the grey wire coming from the regulator. When you turn the key on it bumps the tach, so I know its getting something. Can you check the input with a multimeter?

 

[john from md]

Re: 1997 Force 120 gone wild

It is not unusual to get some oxidation on your connector pins. Tachs don't like this much so clean the instrument contacts, the contacts from the instrument to the bus bars or grounds as per what you have and clean the contacts at the rectifier. Also, if you have a pole selector switch on the back of the tach, switch it through all the positions a few times, this will clean off the internal contacts.

Additionally, the tach runs off AC voltage from the stator. This is usually two yellow or yellow striped wires going to the rectifier on the contacts that have a ~ sign. The grey wire is usually piggy backed to one of these. It has been known for a bad rectifier to cause the tach not to work.

You can check the rectifier input and output with a multimeter. Just use AC for the stator side and DC for the side going to the battery.

You can buy a cheap inductive tach off ebay. I use one all the time when I am tuning the carbs or troublshooting at the engine.

Regards,

John