I have a 1976 mercury 9.8 hp outboard and it keep dieing on me when I go near max or max speed?

Question

it seems like air is getting in the line because the line does not have pressure but at lower speed it runs all day i leave the vent open on the tank and the tank and hose is new and i pump the line with the bulb on it till it pressure up when the fuel comes out of the carb so what wrong with it?

Answer 1

Clean the carb. and change the filter.

Answer 2

if you pump it up till fuel comes out the carb, then you need to rebuild your carb.  be sure to use a new float valve and seat.

gas is spilling out the carb and flooding the engine.

Answer 3

not a lot of detail, but I want to state one other possibility:

it could be under propped and you are over-revving it...if that happens you'll overheat it and it will shut down. check your compression to be sure it's still 100-140PSI

Answer 4

fuel delivery problems...check fuel filter first...may be a bad fuel pump