Fuel problem

1720 keywest / 90 hp 2 stroke yamaha primer ball is sucking flat as a pancake at any rpm above idle.
Here's what i've done already- removed ball and spring from inline check valve at the tank, cleaned the pickup tube that enters the tank witch has a screen on the bottom, replaced fuel line from tank to fuel water seperator,replaced fuel primer ball, replaced filter on the fuel water seperator witch is after the primer ball so that should not be causing the obstruction. I also removed the vent line and was able to blow through it from hull to tank with no problem. While water testing it yesterday, the ball sucked flat and when this happens it takes 5 minutes for the ball to reshape it's self. I got undet the consol and pulled the fuel line off the tank and the ball opned up emediately, i pulled out the pick up tube and the screen was clean. seems like somthing is obstructing the pick up tube every time we go on a plane.

the onlything i can think of is to put an inline fuel filter away from the tank and remove the screen from the pick up tube and hope to catch what ever it is in the fuel line outside of the tank.

Anyone ever had a semmiler issue befor?

Re: Fuel problem

Had a similar problem a few years back. The boat and hence the onboard tank had not been used for a while. Drained the tank and partially filled it. The Suzuki DT140 motor ran great. Then I decided to fill the tank and the trouble started. A coating had built up on the walls of the tank. The coating came free and proceded to block the intake every time the motor revs were brought up.
Let it settle and the motor would fire up ok but call for power and down she went again.
Remedy.
Fill the tank 3/4 full approx.
Rock the boat to slosh the fuel around. Borrow a clean chemical air powered pump and a compressor if you dont have one. Couple up the hoses and drain the tank into manageable buckets. Fasten layered nylon stocking over the out pipe to act as a filter.
Observe and if you see muck then when the tank is empty pump the clean fuel back in and slosh and pump again.
Took about 8 cycles untill I was satisfied.
I then added Stabil to the fuel to help prevent that happening again.
Fitted a large water trap/filter with the replaceable cartridge and have not had a problem since. Been running with no fuel problems for four years now.
On a positive note, you have a good fuel pump.

Re: Fuel problem

thanks James

the fuel tank is 30 gallons and aluminum and about 6 gallons of gas sat in in for 2 months

yesterday we ran 11 gallons in and pumped back out with out straining it just to see if we could pick up a large piece of trash or possible tank lining, but nothing.

i guess we will do it several more times straining the fuel until it appears all clean

could i put an inline filter infront of the primer ball and remove the screen from pickup tube in tank and catch all the trash in the inline filter apposed to pumping the tank 8 times

Re: Fuel problem

ditch the screen in the draw tube, they are useless at best.
but your describing a restriction betwen the primer and the liquid in the tank, like its been pointed out, at least the fuel pump is working well.
the anti-siphon valve is a requirement if any portion of the fuel system drops below the top of the tank.

Re: Fuel problem

rodbolt,

the restriction is between the draw tube screen and the fuel in the tank
if i remove the screen would the junk get caught in the fuel water seperator?
i really don't have the means to flush out this 30 gallon in hull tank

Re: Fuel problem

Yup, but you may consume a bunch of filter cartridges in the process.
The purpose of the intake screen is to prevent large particles from reaching your small in-line filter at the motor thereby preventing that blocking prematurely. There is another possibility, that being that the elbow that connects the hose to the pick up is partially or fully blocked . These are known to corode over time and restrict the flow.

Re: Fuel problem

thanks james,
the elbow is clean and clear
i would replace the screen when i thought i had all the sludge removed
i just don't have the proper setup to flush the tank properly

Re: Fuel problem

I take it the problem is new this season and the primer bulb being installed before the fuel filter is not the problem? Usually I install the primer bulb as close to the motor as possible.

Re: Fuel problem

BK you may have a point there. I dont see that the position of the bulb would make any difference but the I have always installed the bulbs between the canister filter and the motor. Worth a try, can't hurt anything and it might just be the problem.

Re: Fuel problem

It shouldn't matter you're right. There is a restriction someplace, we know that. Now it's a matter of tracing it along the system. My guess also is something in the tank. I have heard on a few different occasions of a small piece of foil or rust or something that is big enough to get sucked up against the intake being the culprit.

One thing you can try is finding a used low pressure fuel pump from an EFI outboard and making a fuel transfer pump. It will hook right up to the intake at the tank and you can use clear hose to see what gets sucked out. Make sure there is some kind of inline filter before the pump so you don't damage it. Best investment I ever made. When I have suspect fuel in a boat tank I can just syphon it out easily. I made two long leads with like 12 gauge wire (overkill I know) and put alligator clips on the end. All I have to do is clip them to a battery and watch the gas flow. I even have an inline fuse on the pump. Yes more overkill. What can I say I'm overcautious.

You know those small, round, styrofoam and foil discs that are usually found under the caps of bottles of 2 cycle oil or stabil or whatever? Usually you take the thing off the top of the bottle when it falls out of the cap. Somehow my dad ended up getting one of those in the gas tank of his backpack blower he uses when he cleans up the yard. He and I spent weeks trying to figure out why the damn thing would not run right. Finally I insisted he empty the tank and get fresh gas and oil from the gas station. What fell out when we emptied it? That stupid small round thing.

Re: Fuel problem

BK not a bad idea on the pump but I would be very reluctant to have all that fuel vapor around with the posibility of a spark from the connections. To get the fuel tank out on most boats is probably not feasible.
Using a big pump with lots of sucktion is the answer.

Re: Fuel problem

It can be dangerous if someone is doing stupid stuff like pumping the gas in a small garage. I used heat shrink butt connectors to hook up the pump leads to my extension leads. I kept the extension leads long so the battery I use is off to the side a few feet. I've seen plenty of marine and auto mechanics use devices like this. Sometimes it isn't always feasible to get to the gas tank on some boats but the fuel lines usually are easy to get to. This way if I can't find the gas tank pickup, at least I can find where a hose is connected and make some sort of inline connection to use my pump. It is faster than opening the deckplate, taking out the sender and fishing a fuel line all the way to the rear of the tank by the pick up.