90 H.P. Mercury 4 stroke giving me issues.

Well here is an interesting issue. My motor started acting up last fall. It inadvertently cuts out at any speed any time. Some times worse some time better. I have treated the gas with sea-foam, I mostly run super. Changed the fuel filter, changed plugs, oil, lower fluid, replaced gas line from the fuel filter back to the tank including the ball. I am beginning to think electrical or possibly fuel pump. I am getting ready to take it in but I fear its an issue they can’t easily find and the large labor bill that goes with that. This motor is a 2002 and has been flawless for me. Thanks for any idea’s or suggestions.

I would start out with checking all electrical connections.Stuff does oxidize and nuts/bolts do loosen up.

A factory service manual goes a long way and can save big $$$$$.

I would start with replacing fuel lines and bulb if they have not been replaced. Many of the older fuel lines would start flaking inside the line causing intermittent problems. If flaking is found be sure to replace the fuel filter as well.

When you say “cuts out” is it going stone dead? No bogging down, no missing, no running rough? Just going dead as if someone turned the key off?

Generally, fuel related problems will cause the above, but they won’t stop an engine dead.

If it’s really going dead, I would strongly suspect an electrical problem. And before someone tells you to replace the CD ignition module, DON’T! You want to be absolutely sure before you start throwing away money.

There are a lot of possibilities if it’s an electrical problem. I’d start by looking for obvious issues. Bad connections, missing wire insulation, etc.

From there, it gets complicated and you may be better off bringing it in to a professional shop.

Grouse

Just 2 clarify. The motor runs great. Starts great. Sounds great. But when I open up the throttle it will cut out. If I put it back in neutral and start to run again it might cut out again, it might not. Very strange. I did replace the fuel bulb and main line. Treated the gas .etc.

It gives great pleasure to announce a fix for my issue. Took it to Anchor Marine in Menominee and he varified the motor was not the issue. With that knowledge and more discusion with him I replaced the starter switch and my motor purrs like a kitten and roars like lion again without issue. It appears the switch was faulting out at high speeds and shutting down the motor. Thanks for ideas and suggestions. This was a tough one!

bigpike wrote:

It gives great pleasure to announce a fix for my issue. Took it to Anchor Marine in Menominee and he varified the motor was not the issue. With that knowledge and more discusion with him I replaced the starter switch and my motor purrs like a kitten and roars like lion again without issue. It appears the switch was faulting out at high speeds and shutting down the motor. Thanks for ideas and suggestions. This was a tough one!

Thanks bigpike i have the same motor ,same year, i will keep this in mind. DK?