1998 90hp force...Why does it run better with more oil in gas????

[A.Hoj]

OK so I've been out 5 times this year with the boat. every time I get up to 4500RPM the motor bogs down, I slow down speed up and its fine for a second then it does it again and again. Last winter cleaned out the tanks wich were nasty. Then I changed the fuel pump, fuel hoses, filters, and it still does it. Today, took it for a ride and still did it after some carb adjustments. so I"m thinking why didn't it do this last year? and I realize I cleaned the tanks in the winter which had very heavily mixed oil/gas and started this season with fresh 50:1. So I add a few ounces of oil to bring the ratio to about 35:1 and guess what? It runs perfect again. Can someone explain why this motor runs great with more oil than recomended?

Thanks!

 

[Frank Acampora]

Re: 1998 90hp force...Why does it run better with more oil in gas????

Magic!

You symptom is a classic for running out of fuel at high speed. You need to double check if there is a filter or screen inside the tank and clean that. If there is a quick-connect on the fuel line, clean that. Remove the carbs and clean them. Pay special attention to the inlet needles and seats. Remove the inlet elbows and clean the whole area well. Reset the float level and reset low speed needles to proper mixture.

Why does it run well on 35 to 1? Couldn't begin to tell you.

 

[A.Hoj]

Re: 1998 90hp force...Why does it run better with more oil in gas????

Thanks. I had one carb off but got little nervous about screwing things up and ended up putting it back on. I ran up and down the delware riverat 5000-5200 rpm for a while after adding the extra oil without one hiccup. I know it could use carb work but I would rather take it to someone. any suggestions in the nj/pa area?

 

[labawg]

Re: 1998 90hp force...Why does it run better with more oil in gas????

There simple! Even though you may(and maybe not) need carb kits, after the first one you'll say why didn't I do this before. I had both of mine apart 5 time this week playing with them and doing little tweaks.

 

[fucawi]

Re: 1998 90hp force...Why does it run better with more oil in gas????

More oil does two things ....First the mixture is weaker ...less fuel more oil same air ..
Second more oil is a better seal on worn oil seals .....some of the 1940's engines I work on need 10:1 not for lubrication but to seal the crankcase bearings ....Stick with the 35:1 if its good for you.

 

[Frank Acampora]

Re: 1998 90hp force...Why does it run better with more oil in gas????

ME! I work on Force engines all the time. Located about 1/2 hour west of Philly. Send me a private message and i will give my email.

 

[A.Hoj]

Re: 1998 90hp force...Why does it run better with more oil in gas????

Frank,

Thanks for the offer! I took all three carbs offf today, inspected and cleaned them. Had to adjust the floats on two of them. Seems to have stopped the leaking from the vent hole I had before, but the needle valves will need to be replaced since they have very tiny grooves in them. Once I take a test ride if it's still acting up I get in contact with you.

 

[fucawi]

Re: 1998 90hp force...Why does it run better with more oil in gas????

there you are the thicker fuel was helping to seal the needle valves sufficeint to keep the float levels reasonable