What are the signs a fuel pump is going out on a boat?

Posted by admin on Sep 9th

My 2001 Larson 265 Cabrio has a Volvo Penta 4.3X engine with high pressure electric pump (O.E. # 3857650). I took the boat out of storage two weeks ago, changed the impeller and battery, and off she went. Ran great. The next day I ran her for 45 minutes, took her up to high speed only to have the engine stall DEAD. No sputters. No coughs. Just nothing. However, prior to it stalling the engine seemed to silently miss, like it was turned off for just a split second and restarted full force. Anyways, it did restart. I got home very, very slowly. It died a few more times along the way, each time being more difficult to restart. So I asked the Yahoo community for answers. They said fuel. Nope. We tested it. Pure, not a drop of water. Change the fuel filter. We did that next. No difference. So after that, I took it out this week. It idles GREAT! Starts right up. Lets me rev it to high RPMs without any trouble. So we actually get under way. We made it less than 1/8 of a mile before it dies again, right after I tried to give it some speed. And again, it starts right back up clean but like before we had to crawl back to the dock. What gives? I am now thinking the fuel pump. Does a pump go out all at once? Or does it allow a little gas in but not a lot? It is getting warm… I want to get to my dock on Lake Michigan… and this is driving me nuts. Thanks in advance.

Filed Under: Water for Gas FAQ
Tagged: Boat, Fuel, Going, pump, signs

One Response to “What are the signs a fuel pump is going out on a boat?”

Sep 9th at 12:03 am By: jtexas

Don’t attach any significance to the fact that you can rev it in neutral but it won’t push a load — this is typical of marine engines. They can run great unloaded then crap out when you ask ‘em to do any real work.

I’d be inclined to rule out an ignition problem first — check all cylinders for spark after it dies. Remove a plug, reattach it to the boot, hold it against the engine block and look for spark while somebody cranks the engine with the key — use a plastic or insulated tool, or just ask your mother-in-law to help out .

If it’s a carbureted motor, you can just check the carb bowl(s) after it dies; if it’s full of fuel, the pump is not at fault. See if the float valve is sticking. Also possible that the float valve is worn down or misadjusted, allowing fuel to seep past and flood the motor.

If by “getting warm” you mean running hotter than usual, could be due to a lean condition (less gas and more air in the mix means hotter burn).

A clogged hi-speed jet will do that to you. Carb rebuild will fix all these problems.

If the carb bowls are empty, then either the pump isn’t pumping, or else you have a massive leak (I suspect you’d have some other indication if that were the case). Check for blockage in the tank, like some bit of debris getting sucked up against the inlet, then falling away allowing it to run sometimes, but not others.