main fuel tank vent problem??

[bigrockets]

17 ft center console boat with 15 gal internal bow tank, evinrude 48 spl outboard. Boat idles and runs fine on the portable 6 gal tank. When I switch to the internal tank when I prime with the bulb I can squeeze the bulb in but is takes a while for it to come out again and the engine will not idle correctly. I can squeeze the bulb after a minute or so and it will be soft to the point I can pump it once or twice. It stalls when going from idle to forward. If I switch to the external 6 gal tank it is fine. Being new to this I'm thinking fuel tank vent may be plugged or something causing fuel delivery problems between the internal tank and the engine. The stalling is really annoying so I'm running on the portable tank. Any advice would be appreciated.

 

[Daviet]

Re: main fuel tank vent problem??

Do you have access the the onboard tank, remove vent hose and blow out. You might also check the fuel pump, might be getting weak and not able to pull gas from the bow of the boat.

 

[Al-53]

Re: main fuel tank vent problem??

you could have something in the vent like a bug nest..OR you could have a restriction in the pick up tube.....some have a screen on the pick up...could be clogged some....

are you using the same fuel hose on both tanks....

make sure the fitting on the inboard tank is not clogged either....and you have a tite fit....or you nay be sucking air also if not tite...

take the vent hose off and blow into it to make sure its clean.....i had some bug build a mud nest in mine one time...now I have a screened vent...

Check fuel pump if all checks out...thats a long pull if the pump is weak....

Al

 

[Barnacle_Bill]

Re: main fuel tank vent problem??

Its normal for the primer bulb to be soft after the motor is started as there is fuel flowing thru it. When vents get clogged the primer bulb will collapse. I would suspect the pickup in the tank or the fuel line. Especially the primer bulb. All must be soft and pliable with no cracks.

 

[mikesea]

Re: main fuel tank vent problem??

if its a vent problem,the easy test is loosen the cap ,and test run.But it could be the fuel pick up.Often people use fittings of differnt metals.Brass and alum are big no no's.The pick up is usually accessable,you can tect your hoses first,because ,the ethonol based gas is killing alot of hoses.The interior hoses have a material that breaks down.My buddies shop is full of problematic hoses.Sometimes you get something floating in your tank,like someone opens the cap and throws it in,I have dropped measuring sticks in(long story)could be a bad squeeze ball too,if you have a snap on connector on the hose ,make sure the ORING isnt cut and sucking air

 

[bigrockets]

Re: main fuel tank vent problem??

OK that is all great advice. I pulled the access cover and it looks like all of the hoses are original. When I get back to NJ I will replace all of the hoses. I'm currently in New Hampshire on Ossipee Lake. The fuel tank vent has a screen. Its pretty green. I took my youngest kid's toothbrush and cleaned off the screen. He won't notice the taste like my wife would. Thanks for all of the help.

 

[Al-53]

Re: main fuel tank vent problem??

if original..I would replace them....and the bulb also....I have seen the insides of hoses bubbled from ethenol and seperated....make sure you get Alcohol resistant lines....most say right on the line itself.....

hope that cures the problem....

Al