FUELED AGAIN Q:

I have a 2000 Four Winns 180 Horizon powered by a 130 hp Johnson outboard. About three years ago, I noticed that when I would purchase fuel, the fuel bulb would be collapsed. It would do this shortly after getting underway and remain so. If I stopped to purchase fuel, it would not inflate but remain collapsed. This in no way affected performance. After docking for the day, it takes about an hour for the fuel bulb to recover. My mechanic has replaced the bulb; he has replaced the fuel line; he has replaced the anti-siphon part; he has replaced the vent … or checked it anyway. It does have a fuel/water separator installed. Finally, I asked him what he thought, and he is unsure. I told him that I would write to you. He thought that was great! Thank you. John Burns Cape May Courthouse, New Jersey

A collapsed primer bulb is indicative of not enough venting and/or a fuel-line restriction. It could also be a bad bulb, but you replaced that. Check the screen on the bottom of the fuel-tank pickup. It may be clogged. There is likely a deck plate in your cockpit sole that provides access to the top of the tank and that fitting. Also check these items: Open the fuel-fill cap and run the boat. If the bulb doesn’t collapse, you have narrowed it down to your vent. Be careful not to do this on a rough or windy day where spray will get into the tank.

You can also connect the engine to a portable fuel tank and run it. If the bulb collapses on the portable tank’s fuel line, you know it’s a problem with the engine (maybe a lift pump). If all is well on the portable, you know the problem is somewhere in your boat’s fuel system.

Likely, the problem is related to ethanol, which degrades hoses. Fuel hoses are laminated, and the ethanol can cause the liner to collapse under suction. This makes it hard to troubleshoot. Change the vent hose and then the supply hose, if changing the vent hose does not work.