WOT problem with 50 HP Force

[lilputput]

I was wondering if you could help me figure out what is the matter with my engine. I have a 1985 50HP Force on a 1985 15' Bayliner Trophy Bass. My Uncle gave me the boat and it will not run wide open. It just creates a big wake and stays at a high idle.I have already changep spark plugs. I plan on changing the LU oil because it's bad and to do a decarb with Seafoam that i bought today. Am going in the right direction with this. Plus I couldn't find the Safoam Deep Creep spray by me can i mix up the liquid some how in a spray bottle. Thanx

 

[eurolarva]

Re: WOT problem with 50 HP Force

Merc sells a product I believe called power tune that is also a decarb product. I just do a maintanance dose of seafoam in my gas tank every third tank full and it works for me. You stated in your question that the motor stays at high idle and leaves a big wake. I dont understand how this can be. A prop wont put out a wake at idle, at least a big one. Do you mean you are getting high rpms with a large wake but the boat is not moving very fast?<br /><br />You might want to consider replacing the impeller, the thermostat and getting a syloc manual for that motor.<br />Here is a link for the manual<br /> force manual <br /><br />Iboats also sells impellers and tstats. If you need help locating these just say so. Welcome to iboats.

 

[lilputput]

Re: WOT problem with 50 HP Force

Do you mean you are getting high rpms with a large wake but the boat is not moving very fast?<br />

Yes thats exactly what i mean should i do a decarb before replscing the impeller and thermostat i thought all that did was pump the water and it does that fine.

 

[eurolarva]

Re: WOT problem with 50 HP Force

Sounds like one of two problems. Just above your propeller is a flat plate called a anti cavitation or anti ventilation plate. This plate should line up with the bottom of your transom. Does your boat and motor do this? Another problem you might be having is you have the wrong prop size or your prop has a spun hub. A spun hub would allow you to go at slow speeds but when you accelerate the prop starts slipping. Motors dont use shear pins they use rubber that snaps when your prop hits something creating a spun hub. To test for a spun hub do this. Draw a line with fingernail polish or a permanant magic marker on prop and prop nut or cone. Drive motor and check to see if they line up still. If not the prop is spun and you will have to get it fixed or replaced. Also post what size and pitch prop you are using.<br /><br />Impellers should be replace every other season. The thermostat can go a few seasons longer but if you dont know when it was replaced you should replace it. If you replace the tstat get a gasket for it as well. An impeller is about 25 dollars and if it goes bad without warning you can easily do 1000 dollars worth of damage. Kind of like doing oil changes on your car. It is an insurance policy for your motor.<br /><br />A decarb would not hurt but I would concentrate on fixing the prop issue and not do anything else till you have that fixed. Then do other things one at a time so if something goes wrong it will be easier to troubleshoot

 

[lilputput]

Re: WOT problem with 50 HP Force

Thanx I know the prop is the right one the boat has ran fine before and hasn't been changed the cavitation plate does line up with the transom. It's always worked before but just isn't this season. I will check for a spun hub today. What exactly is a tstat I'm fairly new to boating and know little about taking down the LU but don't have the money to send to repair shop. I run at low speed alot due to the manatees around us does that have anything to do with it. It has also been layed up for a good 4 months.

 

[lilputput]

Re: WOT problem with 50 HP Force

Oh ya forgot it's using the original prop i belive it's 10 3/8" x 12 1/2". It seems like the carbs have varnish in them or i have a blown head gasket. I haven't had a compression check yet. I'm goin to check the spark tonight. I don't want to put alot of money into it, if it turns out to cost alot i'll just sell it as is. It runs fine at low speed (i.e. first gear). Juudt not at WOT.

 

[eurolarva]

Re: WOT problem with 50 HP Force

tstat is a thermostat. You should get a manual for the motor. New they are about 25 bucks and are often for sale on ebay. They sell them here here is a link force manual <br /><br />I am not ruling out a fuel problem Without hearing the motor it is hard to tell what is wrong. If it idles fine and you can goose the throttle and it goes to high rpm without hesitating or dying I doubt it is fuel related. An impeller is a must. You really should change that when you get your manual. If that goes bad by the time you notice it your motor could be fried. Also check all your spark plugs. What you want to see is a little black oily grime on all the plugs.

 

[lilputput]

Re: WOT problem with 50 HP Force

The Spark Plugs are brand new. My Uncle told me to replace them because the same thing happened to him on this boat. Is there anyway to tell if the engine will run wide open on the mufs out of the water. I just don't wanna drive all the way out there for it not to run wide open. I don't belive it's a fuel problem, because it runs fine when not in WOT. I'm goin to do a decarb. today because i never remember my uncle doin' it and he used to let the boat sit for 6mnts. at a time, But it would always turn right over with a little starting fluid. I think the Decarb will have a big help.<br /><br />I couldn't find the seafoam deep creep by me so what should i use to pour into the cylinders? Oh ya i bought the seaafoam that mixes with your gas can i mix that into what's left in my tank or do i need to get another one? I also have this carbureator cleaner from walmart thats in a aerosol can