***1995 Force 120 Questions***

[Proline_19]

If anybody has a little advice concerning the following problems I would greatly appreciate it. I'm new to the forum so I will just list what I'm experiencing and maybe somebody can help. I purchased a boat powered by a '95 Force 120 about a month ago and I've experienced alot of difficulty starting the engine. First, I drained all of the fuel from the tank, added around 12 gallons of 89 octane, the correct 50:1 mix of 2-cycle, new NGK BUHW plugs, and ran it for about two hours collectively with "Seafoam" in hopes to clean the carbs. Finally I managed to get the engine to idle but once I allow the engine to sit overnight or a few hours it will not restart very easily. Sometimes it takes ten-fifteen minutes to get the engine to start. Once it starts it runs fine as long as the engine is warm. It will re-start very easily (I barely bump the key and it fires), but once you let it sit for a little while it is almost impossible to fire again. I have read alot of postings and found that these engines are rather tempermental and it seems that they are pretty unreliable. At any rate, I have not checked compression, but I have noticed the following: I removed all spark plugs after the last run and I have found that the top two plugs (1 & 2) seem to have the normal amount of carbon buildup. However, the lower plugs (3 &4) are very unusually clean ( you can see the porcelain around the electrode and almost no carbon buildup.) This leads me to believe that I have a problem in those two cylinders... I'm not an expert but it seems that the lower cylinders are not oiling as they should, or perhaps low compression? At any rate, when the engine does fire, it idles well and seems to run pretty well...... when it runs... I haven't had it on the water yet so I can't comment on it's performance in the water. Any advice or help would be greatly appreciated! Thank you...

 

[roscoe]

Re: ***1995 Force 120 Questions***

There is no conventional choke on that motor.
There is a fuel enrichment valve, that releases fuel directly into the intake manifold.

Open fuel tank vent

Check the kill switch, place in "run" position

Squeeze fuel primer bulb till firm.

Advance the throttle 3/4 way, without putting it in gear. -- This is done by either pushing a button in the center of the controls, or pulling the shift handle toward the driver, or raising the fast idle lever, all depending on what control unit you have.

Activate the choke (fuel enrichment valve) by pushing in on the key. The valve is only open while the key is being pushed in.

Turn the key to start while continuing to hold the key in.

Release the key and choke when it starts.

3-5 seconds of "choke", is usually enough.

Be ready to pull the throttle back toward the idle/neutral position, when the engine starts and the revs increase.

Continue to pull the throttle back as the engine warms up.

You should not have to use the choke much, if at all, once the engine has warmed up.

Engine should start within 10 seconds of turning the key.

 

[Proline_19]

Re: ***1995 Force 120 Questions***

Hey, thanks for the reply. So, there is no choke, just the fuel enrichment. I would have never known that so thanks! I need to get a shop manual for the engine... At any rate, can you comment on the fact that the lower two plugs are unusually clean and the upper two seem to have the normal buildup of carbon? I appreciate your time...

 

[eurolarva]

Re: ***1995 Force 120 Questions***

You are going to need a compression test done. If 3 and 4 have real low compression then you will hopefully only have to replace the head gasket. If compression numbers are good next you will have to spark test. From your description it sounds like you are using water muffs instead of going in a lake. If so, you will really notice the problem once it goes in a tank or in the lake.

 

[Proline_19]

Re: ***1995 Force 120 Questions***

So, have you experienced something similar with a Force 120? I was thinking that it might be a blown head gasket due to the unusually clean plugs in #3 and #4, but the engine runs really smooth, well, when it is running... I'll definately do a compression check this weekend and see what I get. Do you have any ranges on the compression numbers? I've read some of the posts and it seems that somewhere around 130-145 psi is a good range for this engine. But, I've also read that the numbers are staggered per cylinder.... Thanks for the information!

 

[eurolarva]

Re: ***1995 Force 120 Questions***

The actual numbers really dont mean much as long as it is within say 5 or 10 lb of pressure. On a warm motor with a real accurate guage it could be around 140 but more likely around 125 on all four.