Stalling at idle

Swampy1229

Recruit
Joined
May 11, 2019
Messages
5
Hello to all...I have a 2009 Mercruiser 350 Magnum MPI serial # 1A348648 the engine performs perfectly with the exception of a stalling issue at idle usually only on initial cold start up. Runs for about a minute and then stalls.....
starts right back up and then she will surge a few times until I keep her running with some added throttle. I have changed the IAC , safety lanyard is operational, cleaned main harness connections, disconnected the shift interrupter. I don’t think it could be the neutral safety switch??....any ideas?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,582
Only with cold start I would suspect the ECT sensor. If sensor is telling the PCM that coolant is warm then it will lean the fuel supply, when motor is cold it needs to be richer to keep running. Start with the motor cold and measure the resistance with the leads removed

These are approximate values in degrees F

210 185 ohms
100 1800
70 3400
40 7500
20 13500
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Ohhh. Surely a diz cap issue. Would be great to see a top of the page write up on how often the diz cap causes issues like this on the MPI. Such a well known issue now.
 
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