familiar story that ends with a anti syphon question

[tigerfishes]

just read on another thread about an anti-syphon on a tank. that got me thinking about my failed attempts to get my boat in the water last weekend. I'll describe what happened and see if it's a problem.
filled the tank most the way up... prior to that there had been no fuel smells. now when sitting or none when running. once i filled it up at the gas station and then drove about 5 miles to the lake, when we got into it i could smell fuel. couldn't tell where it was coming from and wasn't real strong. lifted the dog house and it wasn't there...but on we pressed. this is before anyting was done because this is where we figured out that i had forgotten the keys at home...
try number 2... back to the lake after getting the keys... still have the smell, not any worse so in the water we go... batter is dead... won't start. it was/is a almost new batt that just got charged. to the store... now have a new one with 875 cranking amps...
try number 3... boats on trailer, in the water... won't start. can't tell if flooded or no fuel? still smell fuel. pull dog house off while waiting for neg batt wire to cool... see something wet on port side back corner. water? doesn't feel like water... it goes up the side to above the water... it's soaked... and it smells like... FUEL!... shut everything down and pull out of the water. next day we find that the rubber fuel line is about 5-10 years past it's life time.
here's my question. i can understand why it would leak with the pump on... but why did it start leaking before any pressure was added to the line? it was like as soon as the level of fuel in the tank was above a certain point the line started leaking. should this be happening? is this a problem?

thanks!

 

[fat fanny]

Re: familiar story that ends with a anti syphon question

You obviuosly had pressure build up in your tank for this to occur and your vent is plugged nt allowing air pressure to escape.

 

[NHGuy]

Re: familiar story that ends with a anti syphon question

Disconnect your battery 1st.
I bet your fill line leaked. But if you are smart just check them all and replace any that are brittle or cracked or old.
To the siphon question, if you are cranking the engine the fuel pump will over come the slight resistance in the anti siphon valve and pull fuel to the pump before pushing that same fuel to the carb.
The anti siphon valve will normally be found threaded into the fuel outlet on the tank, remove it and check that it is clean. All it does is keep the fuel from siphoning out of the tank if there is a break in the fuel line below the fuel level in the tank.
The way I understand it, you got fuel in the boat after adding fuel through the filler. Fuel inside the boat had to get there either through the fuel line which is unlikely due to the anti siphon valve, or through the fill tube possibly having a hole or break. That's a lot more likely. There is also a very small possibility the tank has a leak partway up. You could check using a non metal manual air pump attached to the vent tube, after removing and blocking off the fuel supply line at the fuel pump. A little bit of air pressure will leak pretty quickly, if it's hard to find get some spray soap and spray where you think the leak is while it is pressurized.
I hung 10 feet of 5/8" fuel line, 3 feet of grounded filler tube, and 4 feet of vent tubing this spring on a Saturday morning. It didn't cost me $60. Now I am sure my fuel system is safe and not sucking air into the line.
To do that you have to get marine rated fuel hose. The original hoses will be marked with their inside diameter and the marine standards they meet. If in doubt buy a little extra or bring the old one with you. Most boat stores and marinas have the sizes for common applications on hand.
Follow the original routes for your hoses and put all the clamps, hold downs and grounds back. They have a purpose. On my 89 the metal-conductor fuel fill hose was a bear to get off the filler fixture. I ended up removing the filler attachment screws from the boat and the stainless clamps from the hose. I pulled the fixture off the hose before then removing the hose from the tank. Get the new fill hose section the exact length you need and copy any bends in the old hose before installing to the boat. The old rubber vent and supply hoses can be cut away easily.

 

[tigerfishes]

Re: familiar story that ends with a anti syphon question

thanks... i will get under there and find the anti syphon valve...
while i was at work my son-in-law found that the old line marked 1976 was cracked and dryed in several places all along it's route. and that the line had leaked in several places but not as bad as in the back. so he went to Shucks/ORilly's and go new gas line. I noticed that you said to get marine grade line... what's the difference and is it really worth pulling out the stuff he just got? it was only $27 so it's not a big deal if it really matters. none of the line is exposed to sun or weather...

 

[NHGuy]

Re: familiar story that ends with a anti syphon question

I think it has a stamp on it that says "A 'something', Marine grade fuel hose".
I think marine grade will handle anything that environment will send your way, so I'd look for it. The stuff you have may be that type, look for a certification that it is for fuel.
If you need plastic loop hangars for the line I found them with the electrical & tie wraps at Home Depot.
Fuel line that holy, wow! You can expect a huge improvement once your motor is fed fuel without air in it. Especially at higher revs.

 

[PiratePast40]

Re: familiar story that ends with a anti syphon question

Coast Guard A1 rated fuel lne is what you're looking for. A local marine shop should be able to sell it to you off of a roll. If you've got a part of the fuel line leaking or collapsing, then don't mess around with the rest of it - just replace it all. I know that sounds a little rough but piecemeal replacement is shortsighted. If you've got any of the old style inline fuel filters, it's also best to get rid of them and install a newer style spin on type filter/water separator. It's just plain dangerous to be messing around with fuel lines that are old and deteriorating.

 

[tigerfishes]

Re: familiar story that ends with a anti syphon question

thanks guys... it did not have an inline fuel filter... but will find one of the water seperator type and get it inline. my system goes tank-2ft hose-pump-20ft hose-fuel pump on engine. is it best to have the new filter between the tank and pump or the the pump and the engine? i think i read that fuel is supposed to be "sucked" through it not pushed so that would be between the tank and pump?

 

[PiratePast40]

Re: familiar story that ends with a anti syphon question

thanks guys... it did not have an inline fuel filter... but will find one of the water seperator type and get it inline. my system goes tank-2ft hose-pump-20ft hose-fuel pump on engine. is it best to have the new filter between the tank and pump or the the pump and the engine? i think i read that fuel is supposed to be "sucked" through it not pushed so that would be between the tank and pump?

Somethings not right here. There shouldn't be a pump next to the tank. Is this an electric pump or a squeeze bulb? Either way, it doesn't sound like a normal setup.

You're correct in that hoses are normally on the suction side of the pump. In many cases, the pressurized pump discharge line is a steel line. The filter assembly would be before the engines fuel pump. The idea is that if there's a leak, it'll most likely be on the suction line and not on the pressure side spraying fuel all over.

Mount it on the transom or in the engine compartment. Just make sure that you can get to it to change filters and that it's not likely to get in the way or banged around.

 

[tigerfishes]

Re: familiar story that ends with a anti syphon question

it is an electric pump. i only turn it on when starting it when it's cold. i was told by the lying cheat that sold it to me that it was like "the bulb on an outboard". so that's how i've used it and it seems to work fine for that.

had the boat out with the new line... after replacing the starter, the spun hub, and swapping the line going to the electric trany and it does quite nicely.

don't have the new filter yet... but getting some gas fuesm coming from the tank area.... that's the next investigation...