Re: New Force Owner Questions, 1990 120hp.
Top rpm is on the low side of the recommended range, but still ok.<br /><br />Idle is a little high. He probably did this to try to remedy the stall during shifting.<br /><br />Unless you have proof that he did maintenance this year, do it again.<br />New waterpump, new gear oil, new fuel filter, rebuild fuel pump, new sparkplugs.Water pressure guage is a real good idea. There is usually a small plug near the thermostat that can be removed. Screw in a hose fitting, attach hose, run to dashboard, install guage and attach tubing. If no plug is available, you can put a "T" in a cooling line. Everything should be included if you buy a water pressure guage kit, about $50.<br /><br />Decarbing is a 2 part process. The first part is preventative, done by using a fuel additive to prevent carbon build up. SeaFoam or Ring Free are such fuel additives and can be found at most auto parts stores. It also works as a fuel system cleaner and should be used as a preventative maintenance procedure.<br /><br />***If Your intent is REMOVE the existing carbon buildup from the cylinders, heads, and rings, a spray decarb solvent product, such as SeaFoam Deep Creep, is needed to do the decarb process. Some people use one can per cylinder. Free moving rings are what seals your cylinders and gives you compression. Compressed and stuck rings equals loss of compression, and eventually, engine failure.<br /><br />Run engine at fast idle, with engine running, slowly spray liberal amount into each carb, its gonna smoke up the place,<br />spray for a couple minutes, now spray a larger amount into carbs until engine chokes out and stops.<br /><br />Remove spark plugs and spray decarb liberally into each cylinder, install the spark plugs, let it soak for 1 to 6 hours. <br /><br />Start the engine and run at medium throttle, or if at the lake, run it at full throttle. It won't hurt to spray some more through the carbs. Run it for atleast 10 minutes to flush the crud out of your engine. Now remove and clean, or replace the spark plugs. <br /><br />It works well to do the spraying, the night before you go to the lake. This way you can let it soak overnight, and really flush it out at the lake.<br /><br />Don't do this in front of the garage door or the house, unless you want it coated with greasy crud.<br /><br />After you decarb, you may find that you no longer have the stalling issue, and may be able to lower your idle a bit.
