Mercruiser stalls under load

[lee'sdaytona]

Hi all,
I'm new to the forum here and hope I can get some help.
I have a 1987 Mercruiser 3.0 alpha one. When it is put into gear, and under a load, it stalls out. This was an intermittent problem for several years, like when trying to water ski, it would stall out. Now it stalls every time. A quick search told me this might be the lower shift cable?

I also read that this will not happen on land with the muffs on. Well, on my boat it does. I can get it in gear and go just a bit faster than idle. The second I try to throttle up any more, it stalls.

I was going to tune it up, but looking at the general tune up parts, everything looks great. I did clean the fuel filter in the carb, and the fuel filter in the pump got a bit crushed by the compression spring. These filters were replaced only a few years ago. We use our boat maybe 3 times a year.

Any tips or tricks would be much appreciated!

 

[biggjimm]

I think you can check the interrupt switch by simply unplugging the wires on it. At least on mine, when the switch is tripped, it closes the normally open circuit & grounds the coil- wire going to the distributor to kill the ignition. Temporarily removing one or both wired from the interrupt switch prevents the ignition from being "killed"

 

[Rick Stephens]

Sounds like fuel problem. I'd pull your fuel line off the carburetor and stick a container on it and crank the engine, see if you are getting fuel up to the carb. Replacing filters may need to be more often than a few years, that depends on how clean your fuel tank and fuel supplier's fuel is. Doesn't take much to plug up a jet.

After ensuring that you are getting clean fuel to the carb the next step may be rebuilding it.

I agree with biggjimm, although, in the driveway on muffs, you can usually pop the cover off the motor and look at the interrupt switch while someone else throttles up. If the lower cable and interrupt are the problem you will see the switch move out of the valley and onto the 'kill' lobe. If the interrupt is staying still then it is not the issue.

Rick