Rebuilt Mercruiser 140 dies after start

[tcooke]

I rebuilt a 1978 Mercruiser 140Hp and now am having problems getting it going.

Compression is 140 on all 4 cylinders, Spark on all four, timing is set ( at least close enough until I get a gun. And the Carburetor has been rebuilt with the float set at 1/2" and float drop at 1 7/8".

What happens is I get the motor running, it will idle for a bit (30 sec max) then die on me. It will also die when I give it throttle.
I know the carb is getting fuel from the pump, but can't tell if it is a lack of fuel or a flooding issue. The factory air/mixture screw setting is 1 1/2 turns from seat but I had better response at 2 1/2 turns.


Where do I go from here?

 

[bstarved]

Re: Rebuilt Mercruiser 140 dies after start

I'm probably way off base here but this is personal experience from several years ago when i had similar problems with my mercruiser

after similar problems to what you describe and replacing control box
and several other parts
I had electronic ignition, (so i could not change points without complete changeover) (and that electronic ignition is no longer available)

and countless hours of running /stall/checking all the things you have.

my problem originated from the wiring harness, Un beknown to me i was getting intermittant spark,
tests to gauge spark would always be good at idle but as soon as i put a load to it it would cut out

It was a simple fiix, by mistake
i separated the wiring harness and used emery cloth to clean all male and female connections(8?) never had another problem
like i stated probably off base but one never knows
hope it helps