90 Black Max 150hp fuel delivery/pump issues.. ?

[fabrc8r]

I replaced my 115 on my boat with a 150 and it hasn't run right since I put it on. It only seems to like starting on 3/4 throttle and starts in a cloud of smoke. After idling for a while to get good gas flow i can shift and start slowly but then after pushing to full throttle to it bogs slightly then starts fast then bogs again and then starts and goes properly.. it will go up steady in acceleration but only if i ease the throttle open.. also when i shut down the bulb doesn't seem to maintain pressure.. so upon shutdown i have to press the bulb back to prime and start at 3/4 throttle again... is this a fuel pump issue?

 

[CharlieB]

Re: 90 Black Max 150hp fuel delivery/pump issues.. ?

You may have more than one thing not perfected in the fuel system.

Start with the hoses and primer bulb, how old are they? Old brittle, cracked? Poor check valves in the bulb? Replace any that are even slightly suspect, same for the small recirc hoses on the motor.

Then test the fuel pump output, point the carb fuel hose into a suitable container and crank the motor, watch for a strong pulsed stream. Any less will not supply enough fuel at WOT causing the mixture to burn lean, melting pistons.

How clean are the carbs? A dirty carb will not pass enough fuel through the idle circuit for crisp acceleration. As the idle gets dirty so does the main circuit, this is a sign that it is time to clean the carbs properly. Order carb kits, new gaskets, and do the job right, preventing a cylinder melt down.