Merc Classic 50 Stalling

Hi all,
I have a 4 cylinder 2 carb classic 50. Was running fine on a skiing run then all of a sudden stalled at low speed and now will only start for a moment then stops.

I started with the tank and fuel, filters and lines. Then moved on and rebuilt the carbs and fuel pumps with new kits. Then checked the timing and the compression.

I have a fair bit of experience with these engines and never had a problem i cannot get to the bottom of before, but been at this over a month and now totally stuck and frustrated!!

Any help and guidance much appreciated. It will start pretty much right on the key then run for 1-5 seconds and die off very quickly. For the short period it runs it sounds like it is firing on all 4 fine.

Jeremy

Re: Merc Classic 50 Stalling

What year is the engine? What were the compression numbers?

Does it slowly sputter and die or is it an abrupt stop similar to turning off the ignition?

If it is sputtering, can you keep it going by hitting the choke or squeezing the bulb?

Can you squirt a fuel (something with oil) into the carb throats as it stalls and keep it running?

Have you checked for spark after it dies?

It sounds like a fuel problem, but not enough info to tell.

Re: Merc Classic 50 Stalling

Thanks for reply,

The year is 1986.
I cannot remember the compression numbers but they were all within 2-3 psi of each other.

It dies very quickly without sputtering, I’ve either bough new or rebuilt so much of the fuel system that I am starting to think it must be spark related but not sure.
Jeremy

Re: Merc Classic 50 Stalling

Definitely test for spark next. It is an easy test with a spark tester.

If it is abruptly stopping, it would most likely be an ignition problem.