fuel problem

jennykatz · Posted: Thu Nov 06, 2008 8:17 pm Post subject: fuel problem

We have a 06 cape cruiser with twin 30 gallon alum. tanks my port side keeps on running out of gas even though there is gas in there and the gauge shows 1/2 tank ?? We have put in new pickup without the little ball bearings ,cleaned the vent . The f-115 runs good for about 10 minutes then it starts rumnning out of fuel the bulb collapses when I change to the starboard tank everything runs fine ? We changed out the pickup on that tank also ? this is a little annoying to have 10-20 gallons in the port tank and not being able to use it . any suggestions

breausaw · Posted: Thu Nov 06, 2008 8:34 pm Post subject:

Could your tank be pulling a vacuum? Have you checked to see if the fuel tank breather is plugged? The same thing has happened to me a few times over the years with small outboard tanks when you forget to open the breather on the fuel cap.

breausaw · Posted: Thu Nov 06, 2008 9:15 pm Post subject:

Jim,

Thought of one other thing, you could have a faulty fuel selector switch, mine had to be replaced by the previous owner.

Sneaks · Posted: Thu Nov 06, 2008 9:40 pm Post subject: Re: fuel problem

Wefings · Posted: Thu Nov 06, 2008 10:53 pm Post subject:

Jim swap out the valve as Breausaw suggested . I have seen that as well . Bulbs can go bad but if the Stbd tank works Id suspect the valve .
Marc

thataway · Posted: Thu Nov 06, 2008 11:38 pm Post subject:

A number of these problems have been bad anti siphon valves. I had this problem, and know several others who did also. The anti siphon valve is at the pick up tube, and looks like a hose barb. I would carry an extra one, once you replace this one. As long as the vent line is clear, the bulbs can fail, but that is rare on an new engine.

mailbox101 · Posted: Fri Nov 07, 2008 3:18 am Post subject:

Just had the same thing happen yesterday with my starboard tank. Thought it was out and switched to the port tank, but when I filled up it only took 42, not 50. It was the first time that I'd run it down so I thought maybe I was wrong about the tank capacity, but this makes much more sense. Bulb was also collapsed. Thank you.

David B.
08 CC-26 with twin Honda 90's

Almas Only · Posted: Fri Nov 07, 2008 6:38 am Post subject:

If you're drawing a vacuum at the fuel bulb, there's one quick way to eliminate the tank vent as a source of the problem: crack the fill. If the vent is plugged, and you crack the fill, any vacuum in the tank will be eliminated, and the bulb will retake it's normal shape. If that happens, you've probably got a plugged vent or vent line. If not, you can focus on other parts of the fuel delivery system, as noted in the other posts.

A simple way to check out the selector valve is to switch the two feed lines from the tanks, at the valve, so that selecting Port on the valve really connects the starboard tank, and selecting Starboard connects to the port tank. If the condition reverses, you know the selector valve is working, and that you have a problem getting fuel from the tank, to the valve. So, you'll need to take a look at the pickup inside the tank, and the feed line from the tank to the valve. Otherwise, your problem is the valve.

Likewise, if you disconnected the feed line from the problem tank at the valve while there is a vacuum at the bulb, and the bulb still shows a vacuum, then the problem is a blockage at the valve. Otherwise, reconnect the feed, run the motor some more, and the vacuum should occur again. In that case, the problem is the pick up or feed line. Chasing this back a little, if you've determined that the valve is not the problem, then disconnect the fuel feed line from the top of the tank, while there's a vacuum at the bulb. If the bulb retakes its shape, you should focus on the fuel pickup inside the tank. Otherwise, replace the fuel line between the tank and the valve.

No matter what, don't blow compressed air back into the tank. It's a very bad career move.

Good luck!

matt_unique · Posted: Fri Nov 07, 2008 8:20 am Post subject: Gas

I had this problem happen to me on my previous boat....at 1/4 tank of fuel the engine would quit. I verified I had fuel so it was very odd. I finally opened the fuel tank cap and heard the whoosh of air....the fuel pump could not draw fuel beyond a certain vacuum pressure caused by a salt plugged fuel vent.

A somewhat related matter...a few weeks ago I noticed a strange noise coming from inside my port fuel tank when the engine was running. The engine's performance was not affected. After poking around here I'm thinking it is an antisiphon valve issue...how hard is it to replace those? It seems like I have pretty good access to my fuel intake hoses.