Fuel Tank Size Discrepancy

[daniel123]

My AS owner's manual says my 200 Osprey has a 50 gallon tank, but the last two times I've filled it after having it drained for the off-season, it only took 26 gallons. There is no sign of the poly tank having been replaced with a smaller one, and the fuel pick-up has been inspected and found to be ok. Any ideas on what may be going on?

[wingtime]

Are you sure your tank totally empty?  My 170 holds 27 gallons and your 200 Osprey factory tank should hold 50 gallons.  Oh and don't go by your fuel gauge, they are notorious for being wrong.  Even with a new fuel sender after cleaning the tank in my 245 it took over 30 gallons before the gauge even started come off of  the empty peg.

[daniel123]

The tank has been drained by the same marina, by two different mechanics, twice in the past two years, and each time when I went to refill it, it only took 26 gallons. Same exact amount to refill. That's what's baffling me! I wonder, was a 26 or 28 gal tank ever offered as an option for that model or something? I figured the guys on here would know if anyone did.

[daniel123]

Could my tank have a baffle interfering with the drainage/refilling issue? I posed the question to a retired marine mechanic at a boat show over the weekend, about why my 50 gallon Osprey tank has only required 26 gallons of fuel to refill it after the last two times it has been 'drained' for the off season. He said the baffle might be interfering with the draining, and we're only getting half the fuel out. He said the baffle may have even dropped and obstructed the process, which would explain why both times it took about half the 50 gallon capacity to refill it AND why the engine runs as if on bad fuel, which half of it could be -- and getting older each season when only half is replaced. Did those 50 gallon poly tanks have baffles that could be the problem?

[GoneFission]

Baffle would be unlikely to cause that problem, but did you look inside the tank after you "drained" it?  Sometimes the pickup gets bent or comes loose, and even though you think it's empty, it's really not.  You can look in the tank through the pie plate in the deck, but you will have to remove the fuel level sender.  Put a stick of wood down to the bottom and check to see if the tank is really empty. 

You can also get a pretty neat little borescope for only $20 that connects to your smartphone.  This is a great deal and would let you look inside your tank - just do all the connections and turn it on before you stick it in the tank (don't want a spark y'know...):  https://thetechgarage.info/?imt=1&utm_campaign=TTG-Conversions&utm_source=Facebook&utm_medium=attn-mechanics&utm_content=tom-phone&utm_term=LA2KLayered-290k 

[daniel123]

I'm going to follow-up on that gadget;meanwhile, my mechanic said he pulled the intake when I returned the boat to him after the failed trip and he said it looked fine and was not clogged or broken. To be honest, this is driving me nuts. It appears that the last two times I have had it 'drained' there remained 24 gallons, or almost half the 50 gallon tank tank, based on taking only 26 to "fill" it both times when I was ready to use it. Any other ideas? I assume that tank is baffled and if it shifted could that be restricting the draining? 

[wingtime]

I agree you have to take a look in the tank, also look for the tank tag to see what the capacity is.  As mentioned take up your pie plate in the floor and take out the fuel sender.  Don't drop the screws in the tank!

[daniel123]

Ok, will do. Meanwhile, that bore sight site times out without loading. I'll keep trying, but if you have any other leads for info on that, please share 'em!

[daniel123]

That techgarage.info site doesn't load. Would this work?

www.amazon.com/DBPOWER-Waterproof-Borescope-Endoscope-Inspection/dp/B00JERRES6/ref=pd_lpo_328_bs_t_2?_encoding=UTF8&psc=1&refRID=1VH0EQCN96GNVYE4XPEV

[daniel123]

Just confirmed that the tank is a 50 gallon one by the stamp imbedded next to the sender port. What do you recommend I do next to try to figure this out? Since topping it off with 26 gals of Ethanol free gas before my trip, I have burned maybe 10 gallons, which would leave 40. I'm worried that means half of that is now two-year-old gas -- or even older if it wasn't truly drained the past two seasons after which it also took only 26 gallons to refill it. Old gas, and not the wiring harness and all the other things that have been 'fixed' to remedy the stalling and poor running of the engine over the past three seasons. 'Thoughts, anyone? Thanks for any you care to share.

[wingtime]

drain some out fuel out into a clear container and see how it looks and smells.  You can just disconnect your fuel line above the primer bulb.

I bet something is going on with your pickup tube or something.  If it were my boat and I had any doubt about the fuel, I'd drain it out.  I would pull the sender and use a siphon to drain the fuel into a drum of some type.  if it's not too bad you can run it thru a fuel filtering funnel (Mr Funnel) and use mix it with the fuel in your car or something.

[daniel123]

I'll try that. Do those $10 plastic accordion-like siphons at HF work ok for that purpose? Thanks for all the advice, Wingtime.

[daniel123]

OK, no water apparent in the pint I sucked out of the tank via the primer ball. Literally. The primer ball alone wouldn't draw it up from the tank through the fuel filter to the open end of the ball - no matter how hard/I long I pumped it. That was another ongoing problem on the recent trip: priming the fuel line took forever, and the ball would go soft on a regular basis.

Just now, I could get one spurt at a time once I pumped and held my finger over the open end after compressing the (new) primer ball while it sucked air/gas, but I'd lose suction and finally just did the old mouth siphon trick and got it primed and kept it flowing with the primer ball til I filled the jar. Now I have serious BP breath (for Valentine's Day to boot...). Since I had a tube of water-detection paste, I also dipped a stick coated with that into the jar of gas and it didn't change color. But now I'm second-guessing that method because the small amount gas I got in the jar likely had sat in the fuel line and filter and was not from the tank and therefore not an accurate account of the fuel that is down there?   

[Capt. Bob]

I think I know the answer but I'll ask anyway.

Is the primer bulb located before or after the fuel filter?

[daniel123]

After. I cant wait to hear why you inquire...!