Re-Fueling Issue

[Supersportster]

Hey, I have an under the floor fuel tank in my 18 foot aluminum sylvan boat. 1989.

I have done a lot of reading on here and it seems that my tank vent needs to be cleaned/replaced. My problem is that I cant find mine.

I can see the top quarter of the tank by sticking my head in the bilge area, its a 17 gallon tank and on the right corner it has the 1 1/2 inch filler hose, and in the middle there is a ninety degree screwed in fitting will 3/8 fuel line that goes up to feed the motor. Where is the vent??

Second question, how accurate are the fuel gauges on these tanks, cause I can see a little bit of fuel at the boottom of the filler tube, but the gauge reads 3/4's full. Is the gauge off, or is it the venting problem that is not allowing my tank to fill??

Any info is appreciated!

Thanks

 

[user64]

Re: Re-Fueling Issue

Are there any access plates in your deck? There is usually one over the fittings / fuel sender. Can you see a vent on the outside of your hull? See if you can follow it to the tank. Dont think its the case but some tanks vent thru the filler cap and there are 2 hoses there. One fuel fill, one vent. Look under the fuel fill if you can and see if there is a thinner hose next to it....good luck

 

[QC]

Re: Re-Fueling Issue

Second question, how accurate are the fuel gauges on these tanks, cause I can see a little bit of fuel at the boottom of the filler tube, but the gauge reads 3/4's full. Is the gauge off, or is it the venting problem that is not allowing my tank to fill?

Does the fill go straight in from the top and vertical? Or is it at an angle? Is the tank rectangular and flat on the bottom? If the filler is straight and the tank is a rectangular box, that is flat on all sides, you can use a stick to check your tank. Any dowel piece will work, you want unfinished so it absorbs a little fuel to more easily see. You also need to measure from the filler cap down to the tank entrance and subtract that length. Simply divide the remaining stick (inside tank length) in half, then half again, each point marking with a pen and you have 1/4 tank increments, half again and you have 1/8s.

Some tanks are tapered and shaped to fit the bottom of the hull. If that's the case, or the filler goes in at an angle, then you have to get all mathematical and stuff for this method to work . . .

 

[Supersportster]

Re: Re-Fueling Issue

There is an access panel, but it requires me to move my seat to get the last couple screws out. I will do this in a few weeks when i am done with the boat.

It appears to be a flat gas tank, and has the filler tube straight with no vent tube. It goes straight up from the right corner of the tank, through the splashwell with one of those perko caps.

 

[Beefer]

Re: Re-Fueling Issue

You may have a vented cap system, in which case there wouldn't be a separate vent.