Re: 1975 mercury 85hp not starting
yea i have tried everything choking it hard and have the cold start lever all the way up and it keeps doing the same thing as soon as it fires once just dies on me.. is it possible that something in the switchbox is busted that when box reads that it fires once just cuts the ignition off instead of in a running mode
The switch box does not switch modes from start to run, what is happening is that the engine fires and begins to rotate faster than the starter, disengaging the starter gear from the flywheel gear. the starter continues to turn as long as the key is held in the "start" position but is not engaged with the motor.
i suspect the engine is actually starving for fuel, while there is enough to initially fire once it is used up there is insufficient fuel to maintain it.
Check that the choke fully closes the butterfly valves/choke plate, the primer bulb is firm, fuel filters are clear, good fuel.
If the carbs are recently rebuilt have they been tuned, has it been run since the rebuild? The idle screws may have to be turned out a bit to make it a little richer?