2002 Mercury 50hp OB loosing fuel flow

[jerseydevil]

I've replaced fuel line, primer bulb, rebuilt the fuel pump which is the electric type, but I haven't replaced the check valve & when the boats running the bulb doesn't stay hard & the OB cuts out till i pump the bulb up again.What else is left?

 

[DavidMoore]

Most primer bulbs will lose some firmness when the engine is running. Does it feel like it's still full of fuel or does it feel like it is empty / collapsing? If it's feels empty or is collapsing look upstream of the bulb for the problem. Loose connections, pin holes, blocked strainer in fuel tank, blocked fuel tank vent spring to mind.

 

[Bill kubiak]

Are you sure the vent on the tank is open?????
Sounds like a fuel supply issue, to check the fuel pump, disconnect a hose from the pump to the carbs and crank the engine, fuel should spurt out with each revolution.
If the tank vent is closed it will not let air replace the fuel being used and after a while stop the fuel from leaving the tank
if you can pump up the primer bulb until it gets hard the bulb is probably OK, be sure to hold that bulb upright when you pump it up so it gets all gas in the line and no air
Once the engine is running the primer just becomes part of the fuel hose and is no longer firm. If the engine starts and runs for some time before it quits it would suspect the tank vent. If it starts and runs for just a few minutes and then quits I would suspect the fuel pump

 

[jerseydevil]

yes Bill engine runs for some time & then quits till I pump the bulb again. I've replaced all the fuel line & bulb this spring & installed a new filter separator too. the tank is a 12 gal tempo with a screw on cap with a vent screw.