1997 Force 120 losing power

[97trophy]

Hello everyone,<br />I am new to this forum and understand there are many knowledgable people that may be able to help with my problem.I purchased a 1997 Trophy Bayliner 1903 with a Force 120 HP engine last year. When I purchased this boat it had sat for about two years so I had the impellar replaced and had the engine looked over. I have used the boat several times this year, and this is the trouble I am having. It runs great for the first hour and then slowly seems to lose power and run slugishly. The engine will seem to lose power and have trouble starting. I have replaced the starter, plugs fuel filter, gas tank fuel solenoid, and added a new two battery system with charge-pro from guest. I would apperciate any suggestions anyone might have. I plan on purchasing a new engine next season. Let me know if I need to add any more information. If I need to add anymore information to get a reply , please let me know.

 

[22trophy]

Re: 1997 Force 120 losing power

I also bought a Force 120 that sat for two years. It's running fine now. 1. I bought two maint manuals, SELCO Force manual and the Mercury manual. I recommend the SELCO over the Mercury manual. 2. Replace everything,fuel filter,thermostat,etc. 3. Mercury makes a product in an aerosal can that is magic! You remove the carb plastic intake covers, shoot this product down it's throat while your under way- use at least two people. You have to follow their directions. Use your old spark plugs, because this product frees up a lot of junk. Replace with a new set. Good luck! PS:my engine is awesome!

 

[funpilot]

Re: 1997 Force 120 losing power

Hi Kingair, welcome to iboats<br /><br />The only things I can think of that might explain a sluggish response after an hour of good running is fuel mixture. First assure that you're mixing the correct oil and gas mix, or check that the consumption of injected oil seems correct for the amount of fuel burned. Second, check float heights and needle seating to ensure that you're not slowly drawing excessive fuel into the engine, fouling the plugs. Finally look at idle mixture and consistent throttle plate opening on both carburaters.<br /><br />A long shot is that someone has switched the upper and lower carbs or main jet orifices on the carbs... the bottom carb I think is supposed to be .092 and the top carb is supposed to be .090 for your elevation.<br /><br />Your force 120 is very similar to my Sport Jet 120, and is a very strong engine but the electronics are a weak point. You may want to check the spark output when you notice the problem. I'm not sure why you would want to switch out to a new engine. Your's should give you years of service if you can solve your current problem.<br /><br />How long have you been flying KingAirs, if you don't mind me asking?<br /><br />fp

 

[97trophy]

Re: 1997 Force 120 losing power

I appreciate everyones help. I have been flying since 1991. A friend of the family has one that I take on trips. I just flew back from Orlando, a little bumppy as we are awaiting another hurricane.<br /><br />One more question I had regarding my engine. In reverse it seems to be slipping out of gear. Mabe this just needs to be adjusted?

 

[97trophy]

Re: 1997 Force 120 losing power

Can you also give me a good site to purchase these parts you suggested replacing.

 

[funpilot]

Re: 1997 Force 120 losing power

In the lower unit there is a dog clutch and reverse gear. These can get worn, and require replacement. Usually special tools are needed. If you are certain you are properly adjusted to get completely in reverse, replacement is warranted. You can remove your lower unit and bring it in as an assembly for your shop to do the rest of the work.<br /><br />Not sure where your Force parts are, but there is a website for Twin Cities Outboards which is pretty good.<br /><br /> http://www.twincityoutboards.com/ <br /><br />And of course, iboats!<br /><br />fp

 

[eurolarva]

Re: 1997 Force 120 losing power

Here is the merc site for your motor. Everything you might need is here. If you find something you need copy the part numbers down and call your merc dealer to order them. You save shipping that way force 120

 

[trophyman]

Re: 1997 Force 120 losing power

22trophy - you say Merc has a product that cleans out the carbs. What about using Gumout?

 

[97trophy]

Re: 1997 Force 120 losing power

Thank you for everyones help. I ordered a fuel pump kit but I am having trouble finding the carb rebuild. This is what Bam marine said;<br /><br /><br />809807A1 REPAIR KIT-CARBURETOR<br />> Is this a rebuild kit?<br /><br />Bam marine replied,<br />I would think so, however I do not have a list of what is included.<br /><br />Can anyone help me with this?

 

[roscoe]

Re: 1997 Force 120 losing power

I believe the Merc product reffered to by 22Trophy is a decarb product, designed to remove carbon buildup in the cylinders and exhaust manifold, keeps the rings moving like they should. Similar to Seafoam Deep Creep, Ring Free, Power Tune, etc.<br /><br />Gumout, and other carbeurator cleaners are not recommended for 2 stroke motors, as they do not provide the lubrucation needed by the motor, and can strip the protective oil coating from the motor.<br /><br />Asfor cleaning the internal parts of the carb, the ones that matter, you have tom disassemble to get to the vital parts.

 

[22trophy]

Re: 1997 Force 120 losing power

Gents/Ladies,<br />The Magic product I'm refering to is the Merc De-Carb Aerosal Spray product. I've used the car carb cleaner. Learn by my mistakes, it's a waste of time and effort and $. The reason I went with the car product was lack of knowledge. I didn't know of the Merc product existed at the time.

 

[eurolarva]

Re: 1997 Force 120 losing power

That number you posted is a repair kit but I dont think it has gaskets. The gasket kit is FK10023. That repair kit is pretty pricy. I would go to NAPA and get a 18-7037 rebuild kit. This kit comes with the needle, the seat, the welsh plugs and the gaskets you need and only cost about 15 dollars. I believe that repair kit from merc comes with jets, floats, needle jet and some other hardware.

 

[97trophy]

Re: 1997 Force 120 losing power

The part number you posted is for both carbs, correct. This is all I need? How is this job to complete, I am not a mechanic..fairly straight forward?

 

[97trophy]

Re: 1997 Force 120 losing power

I have finished rebuilding the first carb, but had to order another rebuild kit. The book says to turn idle screw in fully and then back out half a turn. Is this all I need to do. I adjusted the float; seemed to be hanging down more than the 7/8 the book said it should.

 

[eurolarva]

Re: 1997 Force 120 losing power

There is an adjustment tab on the float so you can make the adjustment 7/8 inch. It is made by slightly bending one of the tabs near the hinge pin I dont own a force but you may want to recheck how many turns out for that idle mixture adjust. Seems to me it should be at least a full turn counterclockwise from fully seated. This is just a starting position. You will make adjustments to it when you have it at idle speed with the prop in the forward position. Which manual are you using? There should be a pretty good write up on how to adjust it when it is hooked up and in water. Before you install it you should hook up a fuel hose and blow in it while it is up right then blow in it when it is upside down. When it is upside down air should not pass. If it does the float needs more adjustment or the needle seat is not in correctly.<br /><br />When you install it on the motor prime the gas until bulb gets hard. If it will not get hard without gas leaking out the carb you will need to readjust the upside down float height. Yours is probably 13/32 inches. If you have it set to this go to 1/2 inch then try again.

 

[97trophy]

Re: 1997 Force 120 losing power

Thank you.I am using selco. I adjusted the float when I put the carbs back together. They seemed way out of adjustment. So as I understand you, I hold up the float and air should not pass, is this correct? I am also rebuilding the fuel pump. Anything else I should replace or rebuild?

 

[97trophy]

Re: 1997 Force 120 losing power

I just received the fuel pump and I have a question. There is a in, an out and another fitting that has an elbow. On my existing pump it seems that the connection on the left of the pump has nothing attached to it. Is this correct, the manual is kind of vague when it talks about fuel connections.

 

[eurolarva]

Re: 1997 Force 120 losing power

First off. Testing the carb. When you have the carb compleatly assembled and in an upright postion air should flow if you blow into the hose. If you turn the carb upside down and blow into the hose no air should pass.<br /><br />Seems to me your fuel pump should have four hoses. One connects to the gas can, one to the carb and one going to each cylinder. The pump works on cylinder compression. Two lines are vacuum lines and the other two are fuel lines.

 

[97trophy]

Re: 1997 Force 120 losing power

I finished rebuilding the carbs and fuel pump. I took it down to the lake and while in the water performed the decarb operation. We went to Wrightsville Beach, but my girl friend's dog got sick so we had to come home. Hopefully this week I will put the boat in the water and post the results.

 

[97trophy]

Re: 1997 Force 120 losing power

The boat seemed to run great. There was some fuel leaking from the bowl. I may have tightened it too much. Any thoughts?