94/95 Force 120 - Fuel Problems?

[kingstretch]

Sorry in advance for the long post but I wanted to be as detailed as possible.

I recently bought a deck boat with either a 94 or 95 Force 120 on it (difficult to tell based on the serial #). I had the previous owner hook it up to a water hose and run it on a trailer, and it seemed to run fine at the time, but in hindsight I should have had him put it in the water for me to test drive.

It starts up reasonably well most of the time as long as I prime it enough times to get the fuel flowing and will idle and cruise at low RPM reasonably well. It always has a sort of "fluttering" sound to it, where it doesn't sound like it runs particularly "smoothly". At high RPM, it will run for a short time, and eventually bog down and shut off. When I go back to the primer bulb, it's pretty slack, and if I pump it, I can usually get it to start back up.

My fuel flows like this (pretty sure this is normal): tank > pump > filter > carbs

Some notes:

* I replaced all 4 plugs
* I checked compression - between 120 and 130 on all cylinders with no more than 10% difference between highest and lowest
* I replaced the fuel filter and housing with a clear housing so I can see the fuel as well as the cleanliness of the filter
* I drained all of the previous fuel and put new fuel in with a 50:1 ratio to 2 cycle oil
* The primer bulb and fuel line is in generally crappy condition - it feels a little dry rotted - I got a new bulb and line, but I got the wrong size line, so I'm going to return it and get the right one ASAP. Even so, I'm not sure that this is the primary issue.
* When I pump the primer (motor off), I can see the fuel filter fill with fuel. I was expecting the fuel to stop at the pump and not get to the filter since the motor wasn't running and the diaphragm shouldn't be pumping... if my assumption there is correct - this might be damning evidence that the diaphgragm is cracked or the fuel filter is damaged in some other way.
* When the motor is running, the level of fuel in the filter seems to be pretty low - just barely enough to cover the bottom portion of the filter - I'd guesstimate maybe 1/8 full.

I'm thinking that for one reason or another - one of my problems is that not enough fuel is flowing. Either the fuel pump is bad, or somehow I'm getting air in the line and there isn't enough suction between the fuel pump and the tank to keep the fuel flowing. I can't find any local parts for the motor, so I was going to try and order something online. Am I on the right path with a fuel pump? If I'm looking for fuel pump, should I go with the entire pump or just with a rebuild kit?

Other things I've noticed:

* Right after I put the new filter in, I also added fuel and oil. When I pumped the primer, it filled the filter up with a VERY blue mixture (obviously heavy in oil). I couldn't get it to start, so I drained the filter, gave the primer a few pumps to try and cycle out any excess oil, and hooked the filter back up. The fuel seems to be fine from then on, but the fact that it was very heavy on oil worries me a little bit - the gas and oil shouldn't really separate in such a short time period, so I'm not sure how that happened.

Any other thoughts or questions? Thanks for any advice.

 

[jerryjerry05]

Re: 94/95 Force 120 - Fuel Problems?

Gas and oil don't automatically mix.They will eventually seperate after a long time.
I add the oil then the gas.If it's in 6 gal tanks I make sure the gas is put in while I move the nozzle around to help mix it.
The extra oil you put in the system will burn off.You can siphon off a couple of gallons and put it back in the tank.That will help clear up any excess oil in the lines.
Change the hose/squeezie and ANY hoses on the motor.New squeezies can be bad right out of the box. Make sure you don't pump it too hard(not necessary).Once you start running it should go soft.If it goes flat the vent is clogged.
Then rebuild the pump.Usually the diaphram is all you need.Clean the carbs.
Add a small filter between the carbs and the pump.
You have a water/fuel seperating filter in line?Get one.
Ethanol is NOT your friend.J

 

[kingstretch]

Re: 94/95 Force 120 - Fuel Problems?

Thanks for the reply Jerry.

About the fuel:
I had roughly 5 gals of week old mix already in the tank (so it shouldn't have separated yet I wouldn't think), and I added 16 oz of oil (all I had on me at the time) followed by 15 gals of gasoline followed by another 22 oz of oil (after I got home) to get the ratio right. I started the motor on the hose at the house, and now that I think about it, that last 22 oz of oil wouldn't have even been shaken up yet since I hadn't even moved the trailer. I usually try to add the oil first and then add the gas to stir up the oil - I figure that plus the towing will keep it mixed pretty well. I'm betting since I had just added the oil I just didn't have it mixed well enough yet. I'll write that issue off and keep an eye on it.

About the pump/hoses
I bought fresh bulb and hose, but it's the wrong size - so I'm going to return that and get the right size hose. I'll go ahead and replace the hose from the tank all the way to the pump since I'll have the hose handy. I'll go ahead and order the pump rebuild kit today so I can get that in place.

As best I can tell, there is no water/fuel separator unless it's mounted inside the hull close to the tank (I'll check)... I've heard it's a good idea to add one, but where would I mount it? It's a fiberglass hull... would I mount it to the bank of the motor well where it would hopefully stay dry? I'm not a huge fan of adding holes to a boat.

 

[SwampThing]

Re: 94/95 Force 120 - Fuel Problems?

Replace the fuel hose and primer bulb with the correct one. Your problem will probably be fixed.
Both my boats needed new bulbs this year. Neither of the old bulbs was more than 2 years old.

 

[kingstretch]

Re: 94/95 Force 120 - Fuel Problems?

Replaced my primer bulb, all the fuel line between the hull and the fuel pump, and rebuilt the fuel pump this weekend. Runs pretty well, still runs a little bit rough but doesn't cut off on me at high speed. I'd probably lean towards a carb adjustment now. I'm still not 100% confident in the suction between the primer bulb and the fuel pump - when I pump the primer, the first thing that happens is fuel is sucked out of the fuel filter back through the fuel pump and into the primer bulb. It takes me probably 10 or so pumps to get the fuel from the tank to push through to the filter. It's tough to get a feel for unless I have the cover off so I can easily see the fuel filter.

Thanks to all for the help! The good news is that I found out the temp alarm on the motor works... the bad news is that I found out the temp alarm on the motor works.... new problem, new thread.