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.

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

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

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.