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View Full Version : Motor won’t idle or run at slow speed after 30 minutes



Jim Bham
07-27-2019, 09:52 PM
I have a 90 hp four stroke mercury. While in the slip, I can start the motor and it will run great for about 30 minutes. After about 30 minutes at idle it starts shaking and dies. When I try to restart it it will only run a few seconds before it dies again. If I run at a slow speed for a while it does the same thing. If I run at a fast speed the engine works fine but as soon as I go to a slow speed it dies.
I run only non ethanol gas. I have added sea foam several times but it doesn’t help. No alarm goes off and water is coming out the pee hole just fine.
Any sugestions will be appreciated.

mechanicman
08-09-2019, 08:57 PM
Is this an efi engine?

Jim Bham
08-10-2019, 05:16 PM
Yes it is

mechanicman
08-10-2019, 08:59 PM
Check the IAC. Idle air control it may be dirty. It controls the idle. And it acts like a dashpot on deceleration. To help control stalling. Not sure if it can be cleaned.