How to test a fuel pump

[finfanmo1972]

I am a new boat owner and am having fuel delivery problems. I disconnected the fuel line at the carberator--no fuel flow. I then connected a fuel hose directly to the fuel pump with the other end submerged in a gas can--no fuel flow. Before I buy a new pump, are there other tests (vaccuum, anti-siphon) to perform or other things to look for? I am fairly mechanically inclined, but have no experience with boat motors. FYI: Mercruiser Alpha One 4.3 liter w/ mechanical fuel pump. Thanks for any help.

 

[hullofalottatrouble]

Re: How to test a fuel pump

fin,<br /><br />im no expert but i recently went through some fuel pump tests myself..<br /><br />from your information thou it sounds like your pump just isnt working..<br /><br />but in any event here is what i did..<br /><br />mercruiser 260.. <br /><br />T'd in a fuel pressure gauge between pump and carb.. fired up and only registered 2.5 PSI on the gauge.. definitely lower than the 5.5 spec..<br /><br />T'd in a vacuum gauge between pump and fuel/water separator and registered 5in HG way too high.. seemed to indicate a restriction between tank and pump.. <br /><br />so pulled the fuel/water separator it was clean and clear.. pulled the pickup out of tank.. it was clean and clear..<br /><br />so i then bypassed the anti-siphon valve.. and fired it up.. read 0in HG.. seemed to indicate bad anti-siphon valve to me.. pressure test also read 5.5 afterwards.. <br /><br />thou again.. if you pump isnt pulling any gas at all.. seems like you might have more of a problem than i did..