possible vapor lock?

daymienrules

Cadet
Joined
Jun 9, 2009
Messages
24
I'm brand new to boating, but not at all to engines, so maybe you guys can help.
Yesterday out on the water I had a stall out, followed by total lack of engine restart. After towing it to shore, a little diagnosis found I had a no-fuel situation. Starting at the carb and working down, all systems checked out until I got to the tank. Applying suction to the fuel supply hose connected straight to the fuel tank pickup gave me nothing. Dirty jokes aside, I'm sucking on the gas line and no fuel is coming out, And I can't blow into it either. As if it were totally clogged. The section of hose from the tank to the pump was free and clear, so that left the in-tank pickup which I obviously cant access in a tank covered by the deck.
In order to fix it, I took off all 3 lines connected to the tank, and removed the fuel gauge sender. I plumbed the fuel supply hose straight into a separate gas can and it fired right up. Frustrated, I hooked it all back up as intended in order to put it back on the trailer, but it fired up. It ran beautifully the rest of the day. And as you all know, there is the obligatory group of 8 people all standing around waiting for it to be fixed so their fun can continue. fun times.
Details:
1999 Wellcraft 17ft. 4.3 volvo, 2bbl holley carb, elec fuel pump, 20gal tank totally full of premium, outside air temp about 115F. Boat had sat for about an hour, then I started, idled out, opened up to half throttle when it bogged and died.
So, is their something in side the in-tank pickup that can vapor lock or otherwise clog the line? Especially that will prevent me from blowing air in or sucking fuel out. I've only put 20hrs on the boat, but it's never had a problem like this at all.
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: possible vapor lock?

There is a USCG required fitting on the tank that is about 1 in long. It is a anti-siphon thingy. Sometimes they get corroded and will not work. If you have an aluminum tank it may be corroded or plugged with aluminum from the tank. Aluminum from the tank???? Yes, the ethanol that is in the gasoline we use will dissolve the aluminum tank and pass it on as very fine granules. Not to mention any moisture causing corrosion in the tank (Oh, yeah, I wasn't going to mention that). He He.
 

gostephen

Seaman
Joined
Apr 9, 2009
Messages
69
Re: possible vapor lock?

i had a problem with the anti-siphon(one way check valve) valve mine was plugged form old fuel turning to a gel. i could run for a about 10 minuets at idol and it would die(less time at higher rpm)

check this valve it should be right on tank ware the fuel line connects to the tank, mine looked like a normal barbed hose fitting
 

daymienrules

Cadet
Joined
Jun 9, 2009
Messages
24
Re: possible vapor lock?

thanks! At the time I had no idea the anti siphon even existed in there sine it looks like a standard brass 90. It sounds like the most likely culprit for my problem, if not the only culprit. Time to replace it. And by replace it, I mean buy 2 of them to have a backup on board. This thing is turning into the noah's ark of boat parts.
 
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