My 15 HP OB Merc would not start (not even a hint of firing) unless fuel was spray injected into the carb and it would not stay running any longer than that spray would last. The tank bulb pumps up hard when squeezing and I don?t see any fuel in the water behind the boat. I took the carb/fuel pump apart expecting it to be clogged up but was surprised that is was not. There was some debris but nothing clogged. The pump diaphragm seems intact but much of that debris I mentioned appeared to be a rubbery substance. I also found a small amount of gelatinous substance in the primer pump area. I dipped it in carburetor dip for a few hours, washed, blew dry and reassembled setting the float high (just to see if it was set to low as a root cause). The result was the same. It still won?t start without external fuel assistance. I did discover that that I could get it started by manually manipulating the throttle plate while depressing the choke primer button multiple times but it won?t stay running unless I continue to depress it while also squeezing the tank primer bulb and feathering the throttle; yes this takes three hands.
I recruited some help in manually manipulating the throttle, primer button and bulb to keep it running while I checked the ?signal line? for the pump from the main case and noted it to be a positive pressure from both source connections. Is this correct or should it be a vacuum?
Help! Am I on the right path in thinking the fuel pump is the root cause here?
Raymond
I recruited some help in manually manipulating the throttle, primer button and bulb to keep it running while I checked the ?signal line? for the pump from the main case and noted it to be a positive pressure from both source connections. Is this correct or should it be a vacuum?
Help! Am I on the right path in thinking the fuel pump is the root cause here?
Raymond