Fuel Supply Question

[C17fly]

I'm getting ready to start this engine for the first time in about 5 years, my "new" 1998 Glastron GS249 with VP 5.7GS PBYC. I was wanting to check the fuel supply and am a little baffled (like the fuel tank I suppose). I removed the fuel line at the filter/pump assembly. I blew into the line (upstream side) with a air hose and it didn't blow through easily at all. I expected to either hear bubbles indicating there was fuel or water in the tank or else just a rush of air indication the tank was empty. It seemed to be completely blocked somewhere. I thought that maybe the fuel cap sealed better than I would have thought so I opened the cap and tried again -- same result.

Is there something about boat tanks that I don't know about or is something completely plugged? The tank smells OK, maybe a little like alcohol (ethanol) but not like varnish. I can see where the filler pipe and the fuel line go through the bulkhead on the forward wall of the bilge area but can't find anywhere that there might be any access cover or anything, even for a fuel level sending unit. Immediately forward of the engine is a 2-person sleeping berth so if the tank is that far aft it would have to under that. I checked around there but I'd have to remove the wall and floor carpet to see anything I guess. Is that where it's likely to be? I'll have a hard time getting this ole engine going without fuel!

If this would be better posted in another forum please feel free to move it or let me know and I'll copy and re-post. Thanks for any tips anyone can provide.

 

[shrew]

Re: Fuel Supply Question

I'm not sure if the fuel pickup will allow backflow. I didn't think it would. You could look to see if the tank vent is blocked. I would be more worried about 5 yr old fuel, regardless of what is smells like.

 

[steelespike]

Re: Fuel Supply Question

Some tanks the pickup has a check valve.
I think set it up so you can syphon off some fuel.
Some additional hose so you can get the end below the tank over the side or maybe stuck through the hull drain.
If some one blocks the vent you may be able to blow in the filler to get the syphon started into a clean can.
If there is any gunk in the tank it will show in the can.
Add something like sea foam to the tank and top it up before starting.
Always assume the storage will be longer than a few months and add a fuel stabilizer.

 

[Bondo]

Re: Fuel Supply Question

I'm getting ready to start this engine for the first time in about 5 years, my "new" 1998 Glastron GS249 with VP 5.7GS PBYC. I was wanting to check the fuel supply and am a little baffled (like the fuel tank I suppose). I removed the fuel line at the filter/pump assembly. I blew into the line (upstream side) with a air hose and it didn't blow through easily at all. I expected to either hear bubbles indicating there was fuel or water in the tank or else just a rush of air indication the tank was empty. It seemed to be completely blocked somewhere. I thought that maybe the fuel cap sealed better than I would have thought so I opened the cap and tried again -- same result.

Is there something about boat tanks that I don't know about or is something completely plugged? The tank smells OK, maybe a little like alcohol (ethanol) but not like varnish. I can see where the filler pipe and the fuel line go through the bulkhead on the forward wall of the bilge area but can't find anywhere that there might be any access cover or anything, even for a fuel level sending unit. Immediately forward of the engine is a 2-person sleeping berth so if the tank is that far aft it would have to under that. I checked around there but I'd have to remove the wall and floor carpet to see anything I guess. Is that where it's likely to be? I'll have a hard time getting this ole engine going without fuel!

If this would be better posted in another forum please feel free to move it or let me know and I'll copy and re-post. Thanks for any tips anyone can provide.

Ayuh,... That's as it's Supposed to be,...

At the top of the tank, the outlet fitting is the anti-siphon valve,...
It protects ya from fillin' the bilge with Gas, in case of a fuel line rupture...

 

[C17fly]

Re: Fuel Supply Question

Ahh, that's good to hear. Thanks to all, Bond-O, Steelspike and Shrew. I'll try to get back over there soon and sample some fuel (if there's anything in the tank at all). I can see I have lots to learn about the differences between cars and boats

 

[Silvertip]

Re: Fuel Supply Question

And now that you put much more air pressure on it than it normally sees, it will likely be stuck closed. I would be more concerned about the three year old fuel in the tank. I would attempt to drain that old fuel or at least fill the tank with fresh, and pump some through the line before attempting to start the engine. After three years, there is a good chance the engine fuel system needs serious attention -- as in carburetor rebuild. Remember, clogged carburetors cause an engine to run lean. A lean engine also means lean lubrication so you could destroy a perfectly good engine. If the engine acts up at all you need to stop it and find out why. You won't like the bill for a rebuild if all it was a clogged carburetor.

 

[JoLin]

Re: Fuel Supply Question

I can see where the filler pipe and the fuel line go through the bulkhead on the forward wall of the bilge area but can't find anywhere that there might be any access cover or anything, even for a fuel level sending unit. Immediately forward of the engine is a 2-person sleeping berth so if the tank is that far aft it would have to under that.

Before you go pulling things apart, double check. There are only so many places to fit stuff on a 24'er, and if yours is like my '99 Chris*Craft 24 express, as you go forward from the stern there's a bulkhead ahead of the motor, followed by the tank, followed by another bulkhead, followed by the mid-berth. Hard to believe there's no access hatch on the deck for the fuel sender, but maybe not.

 

[C17fly]

Re: Fuel Supply Question

And now that you put much more air pressure on it than it normally sees, it will likely be stuck closed. I would be more concerned about the three year old fuel in the tank.

Sounds like that'd be a problem. Is there anyway I could check to see if it's stuck closed? After reading all the above, I was thinking of getting a length of fuel line and running it out the bilge drain hole and capturing it in a clear container (for inspection). If nothing runs out, pressuring the tank through the filler neck and if nothing still assuming the tank is empty. I could then put some fresh fuel with Sea Foam and try again to check the smell, color and clarity of the fuel. Does that sound like a reasonable plan of action?

 

[C17fly]

Re: Fuel Supply Question

Before you go pulling things apart, double check. There are only so many places to fit stuff on a 24'er, and if yours is like my '99 Chris*Craft 24 express, as you go forward from the stern there's a bulkhead ahead of the motor, followed by the tank, followed by another bulkhead, followed by the mid-berth. Hard to believe there's no access hatch on the deck for the fuel sender, but maybe not.

Thanks, I do think I'll go back and re-check the layout of things and make sure I haven't missed any possible access covers. Although if the fuel samples are OK, I may not need to access anything further. Fingers are crossed!

 

[Silvertip]

Re: Fuel Supply Question

Pressurizing the tank with the idea that you can force fuel out is contrary to how the anti-siphon valve works. You merely force it "more closed" so the only thing you might accomplish is to rupture the tank (provided you seal the vent line when you try that.). When I said the valve would stick by applying pressure to HOSE it forces the check ball backwards to seal air going INTO the tank. Forcing air INTO the tank through any other orfice will cause the valve to close more tightly in the other direction. Adding sea foam does not make bad gas good again. Fine to check for water but you have a couple of options: 1) depending on how much fuel is in the tank you can add at least the same amount of fresh fuel and it should be fine. 2) drain it and use in your gas powered yard equipment.

 

[C17fly]

Re: Fuel Supply Question

Yes, I was trying for option 2, drain it. Apparently I still don't have clear concept of how the anti-siphon valve works, etc. If I can't attach a fuel line extension and run it through the bilge drain (won't drain due to anti-siphon valve) and I can't pressure it out due to the same, then the only other way I can think of is to attach a cheap electric fuel pump to the line that did go to the engine fuel pump/filter, then attach more fuel line to that, then out the bilge drain hole. That should work, right? As I said, I don't know whether there's any 3-5 year old fuel in the tank or not, and I understand Sea Foam doesn't polish varnished gasoline. I'm just trying to clean the tank as best I can before running the engine pump/filter. So if I do this and nothing comes out, I guess I'll put some gasoline with Sea Foam in it (to help clean the tank and lines) and pump that out, then put a couple gallons of fresh gasoline in the tank and pump that out until I get good, clean fuel. Then I can proceed with all the other stuff I need to do to try starting this engine.

 

[NHGuy]

Re: Fuel Supply Question

The system only ALLOWS fuel to be PULLED from the tank by the fuel pump. So get some way to pump out the old fuel, it will not siphon because there is an anti siphon valve which will not allow it. An anti siphon valve is a one way check valve that has a soft spring on it. You can either suck it out the fuel supply line or access the tank top and get a siphon or pump going through there. To get the old fuel out, and you should, you will have to figure it out.
The above poster is right, get the old fuel out and refill with fresh fuel, if you try to run off 5 year old fuel you will create more costs than the effort required to remove the old stuff.

 

[jdlough]

Re: Fuel Supply Question

The anti-siphon valve is a cheap ball-and-spring thing that from the outside looks like any normal fuel fitting. It is supposed to stop any slow siphon fuel leaks from a cut line or broken fitting below the fuel tank. It is always closed, until your motor draws enough to pull the ball against the spring away from the ball seat, allowing fuel to flow by.

Here's a carpy pic I drew to demonstrate the anti-siphon valve:

(Click to embiggen)