85hp force motor wont go past 10mph

[pugerz]

I have a 1985 85hp motor on my fiberform that ran fast last year before last time out last year. The last time out last year i could not get it to go past 10 mph and I took out yesterday, ran somewhat better but still same. bog down at WOT and want to die. In nuetral motor revs up real nice and it starts real nice but issues of speed. will run all day at lower speed with no issues. I took some pictures of the gear oil and a silvery oil leaking out above the propeller opening, i think it is the intake. Gear oil looked like oil, noticed no water in it. It leaks a green fluid out from under the cavitation plate. I plan to change the gear oil and plugs this week and i got a manual. I noticed a yellow wire was off the terminal block that i reattached when i inspected the motor. Please help me out recently laid off and dont have money to take to mechanic right now, but have the clymers manual. Do these fluids indicate any issues with this motor? maybe the cause for bad performance or is this common?

 

[pnwboat]

Re: 85hp force motor wont go past 10mph

It's hard to tell what type of fluid that is. Lower unit gear oil has a very distinctive sulfur type smell to it. If it has any gas smell to it at all, it's probably unburned gas/oil mixture The opening above the propeller is the exhaust from the motor. The oil coming out of there is most likely raw fuel/oil mixture.

You may have a problem with one of the cylinders not working properly which may be dumping raw gas/oil out the exhaust. Need to perform some basic compression, ignition and carburetor tests. Your manual should have the basic information on how to do this.

 

[RRitt]

Re: 85hp force motor wont go past 10mph

LOL, I had same problem once. It got better after I brought in the anchor.

 

[Frank Acampora]

Re: 85hp force motor wont go past 10mph

They always run well in neutral because it takes very little horsepower and fuel to rev up. If it runs smoothly at lower speeds then goes "flat" or "sags" as you give it throttle, this is USUALLY due to lack of fuel.

Check to make sure that one cylinder or more is not firing, Check compression on all three, and if all is good, then check the complete fuel system for gunk and partial clogs. replace the fuel pump diaphragm.

 

[pugerz]

Re: 85hp force motor wont go past 10mph

thanks, I will check compression and look at fuel delivery system. If fuel has a higher oil ratio than 50 to 1 would that cause that silvery slime to come out the exhaust port? That silvery slime coming out the motor and the oil coming out under the cavitation plate is something i never noticed before when running motor last year never saw this happen. The guy i bought the boat from last year said he ran motor at a 24 to 1 ratio and when i put gas in last time i put in about that ratio with regular gas instead of premium. I have learned since that the motor requires a 50 to 1 ratio. Hopefully nothing is major here to rectify. Motor runs great at lower speed with no apparent misses. Thanks for all you guys efforts here in helping us novices out with questions. It really helps to have this forum.

 

[pugerz]

Re: 85hp force motor wont go past 10mph

I took the boat out today. I changed the gear oil, changed the spark plugs even tho they looked ok. Dumped out all the old fuel into a 5 gallon tank and replaced with premium mixed with the proper oil mixture. No issues, this motor took off. No leaks from the exhaust like before. I did try to change the fuel pump diaphram but two bolts will not turn and have some rust on them. I have the diaphram but could not get the bolts off, the other 4 no issues. I got maybe 30 mph out of the motor hope to do some tinkering and get it up higher, its on a 75 fiberglass 16 fiberform. Any suggestions? Did a compression test. 125, 119, 121 its a 85 us marine. i want to redo all the decals on the cowling including the usmarine one. Any Ideas on where i can get them? My son is a marine and just got to camp leatherneck in afghanistan last week for a year.

 

[CATFISH KING]

Re: 85hp force motor wont go past 10mph

thanks for the fix it info. mine did the exact same thing last year. i plan on replacing plugs, fuel pump diaphram, and fluids. hopefully this will get mine going as well.

 

[pugerz]

Re: 85hp force motor wont go past 10mph

Yea i was running a very rich oil/fuel mixture when i was having issues. It was probably close to a 24:1 mixture. I was getting all this unburnt fuel coming out the motor. I also was just dumping oil into the tank then filling up with gas, hoping that would mix it as good as it needed. Now I pull the tank out put the fuel in and oil and shake that tank, over and over. Maybe overkill I dunno but i am having no issues with the motor bogging down anymore. No more slime coming out my engine either. I am using a mercury engine clean product now in my gas to clean out the carbon in the cylinders. I am hoping to get the motor pushing my boat 60+ mph when its cleaned out. hehe.