Fuel Question Force 90 HP

I have a question regarding the fuel in my boat. This may sound dumb but I am new to boating. I bought a used Key West 1720 DC that has a full 31 gallon inboard fuel tank. The guy I purchased the boat from bought the boat just becauuse it had a Yamaha 115 4 stroke motor. He put his older Force 90 HP on the boat to sell. I have been running the boat with an external 8 gallon tank. I put in 3 quarts of 2 cycle oil as a dealer said just to be safe. He said a little too much oil is OK and not enough is bad news. I have taken the boat out twice since I put the oil in to mix it up good. I got rid of the external tank, put a new water/fuel separator on, and connected the hoses properly. Sorry for rambling! Do boats with inboard fuel tanks have a fuel pump or is it in the motor? Just messing with the fuel line in the yard I can't get any fuel to pump from the inboard line with the siphon pump. Any help would be geatly appreciated.

Re: Fuel Question Force 90 HP

the fuel pump is on the motor. if ball wont prime put somthing in end that attaches to motor and squeeze bulb its probably air bound when air out and pumping gas rehook to motor. also check to see if there is a relief valve on tank make sure its open.your fuel mix is 50:1 no less no more. It will show on back of oil jug how many oz.

Re: Fuel Question Force 90 HP

4 cycle engines do not mix oil with gas so the gas in the tank had no oil in it. Your Force uses 50-1 gas to oil mix. 1 pint per 6 gallons gas is 48 -1 so your 31 gallon tank should have 5 pints of oil added. 3 quarts is a little rich but the engine probably won't even notice the extra. Like the dealer said: better to have too much than not enough. Be sure to use outboard TCW-3 oil. Regular automotive oil contains additives harmful to 2 cycle engines.

Re: Fuel Question Force 90 HP

Just remember that rich in oil means LEAN in gas. Yeah, it's only about 1 pt too much oil in 31 gals of gas, so it's not a concern in this case. But way too much oil can cause a fuel lean condition bad enough for damage to occur.

Re: Fuel Question Force 90 HP

Umm.... Did you say three QUARTS to EIGHT GALLONS of gas??? THat seems to be WAY too much oil.

Re: Fuel Question Force 90 HP

gunner1 said:

Umm.... Did you say three QUARTS to EIGHT GALLONS of gas??? THat seems to be WAY too much oil.

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That would be a 10 to 1 ratio. I doubt the motor will run with that mixture. The dealer probably meant to mix the 30 gallon tank with 3 qts of oil. That would be a 40 to 1 ratio.

Re: Fuel Question Force 90 HP

eurolarva said:

That would be a 10 to 1 ratio. I doubt the motor will run with that mixture. The dealer probably meant to mix the 30 gallon tank with 3 qts of oil. That would be a 40 to 1 ratio.

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Yeah, that's what I assumed also, 3 quarts into 31 gals.... but you know what happens when we assume!