anyone familiar with 4 stroke Mercury outboards?

2002 40 hp 4 stroke EFI, was running down the river last Saturday, boat just started to slow down, twist throttle, no response, dropped to idle, idles fine, pumping the ball, got firm, waited, ran down the river for a mile or so, same same, full of fuel. replaced inline and bowl filters last nite, started rite up, noticed no fuel in the opaque bowl, pumped ball, bowl filled up, engine idling fine, watched bowl level slowly drop down, pumped back up, slowly dropped down..... fuel pump?...

 

Sounds like a fuel pump problem. Quick google suggests that they are rebuildable, but replacement cost is not outrageous.

It is a B.O.A.T. (Break Out Another Thousand)

Good luck

 

thanks, one pump is good (the easy one) water trial on Saturday or sunday….

 

Very familiar. High likelyhood of fuel pump failure with what you describe, but could also be an air leak in the fuel line. One thing I suggest is replace all the fuel lines with clear/see through lines like Tygon lines. I do this on all my outboards. Then you can see where air bubbles happen. If a fuel pump is bad you will see air bubbles above the pump but not below, and if any of the connections are bad you'll see air bubbles below the pump. Two very important things... do not bother with rebuilding fuel pumps and do not, no matter how tempting the price do not buy anything other than a genuine Mercury fuel pump. Chances are the only fuel pumps you can replace diaphragms on are above the 25hp mark anyway.

 

@jethro
schweet, imma off next Friday, so I should be there around 10 am, want to post up yer addy and where should I park it?

 

if the above things don't work try loosening the gas cap. if that works the vent in the cap is plugged or closed.