fuel tank vent

[SANDMAN]

Took my boat on test run today and after 4-5 minutes notice engine light came on then slowed down went off then started off and it came on again.I started searching for the problem and found fuel ball was flat as a pancake,pulled fuel line off the filter and the air filled the ball again but went flat in 4-5 minutes again.It sounds like a fuel vent clogged or could it be pickup tube in the tank?How about the sending unit bad? Any ideas would help, thanks sandman

[KeithG]

If it were your fuel vent, you would be able to remove your fill cap and the vacuum would have been released.  You should be able to duplicate this on the muffs.

Keith

[MichaelO]

I would suspect an anti-siphon valve on the tank being clogged.  It may be the check valve in the primer bulb.  You fuel hose could be clogged somewhere between tank and motor.  Your fuel filter may be clogged.  The fuel tank pickup may be clogged.  The first check would be to open fuel fill as mentioned (eliminating a clogged vent).

Cheers,
Michael O'
1975 Aquasport 170
Pine Creek
Western L.I. Sound

edit: Might pull fuel filter and dump it.  Check for ethanol/water sludge.

[Undertow2]

Ah..Ethanol.  The great big moisture sponge...

[GoneFission]

I would guess you have checked this, but is the fuel line kinked somewhere?  That could do it as well...

[aqua70]

check the screen on your tank vent. It may be corroded/salted up enough to restrict air flow. Sometimes they clog up on the inside of the screen.
     To see if it is that, run the engine with the fuel fill cap open. If you still have the same problem it is not at the tank.

[John Jones]

all good advice.
The flat bulb means a restriction somewhere between the bulb and the tank pickup if the vent is not blocked.