2018 Mercury 150 EFI hard to start hot

[Jeff J]

Motor has been running great and starts easy cold but go for a restart after it is warmed up and it repeatedly fires and dies. I don’t see anything in the service manual covering the issue. It can be started by giving it a little throttle but something isn’t right for that to be a requirement on any EFI engine.

 

[alldodge]

Don't know the motor but I might look at the IAC and see if it needs cleaning

 

[Jeff J]

That was the second thing I tried before asking even though it usually runs like crap when the IAC needs cleaned. For some reason, of the 3 motors like this I care for, this is the only one that ever gives me trouble with the IAC getting dirty. The first thing I did was change the fuel filter even though it didn’t give any of the normal dirty filter signs. I have not checked the fuel rail filter or pulled any injectors. I would expect different problems with those too. Hard to start hot whether on the lake or idling at the shop sitting in the tank.

 

[QBhoy]

Have you ever removed the cleanable/serviceable fuel filter strainer in the fuel rail ?
How’s the throttle position sensor ? You can test this, as per the manual.
Could be the coil packs too. They can cause issue with varying heat conditions.