Guys ,
The Stbd motor (700sci) is idling good and in neutral can rev pretty good until the ecu cuts (around 2200 rpm) , but whenever i shift (fwd or rev) it stumbles and cant rev beyond 1200-1300 rpm and doesnt run right and dies, my mechanic changed the fuel filters and still no progress .

Can it be the shift interrupt sensor ? Any ideas ?

tks
Sherif

its a 2008 boat by the way .tks

Replace the IAC.

I worked on a buddys 2008 39 cig with 700 had the identical issue,found the shift interrupter bad,the boat will run with it unpluged,it sends a signal to the ecu to let the ecu know if its in reverse or drive to control the rev limiter,its in the back above the gimbal ring,unplug it your boat will run fine with out it,if the issue goes away after a week of use then you could replace it,

Replace the IAC ... And pray it didn't take out the ECM

my guess is the map sensor.

The IAC does nothing other than control idle,all it is is a pintle on a stepper motor controlling idle by opening and closing the idle cavity on the throttle body,when closed idle is low when open idle is high,

IAC has nothing to do with drivability once you are off idle

Thanks for your help , can you advise on the location of the shift interrupter ?

i mean any pics ?

Update: The mechanic disconncted the Shift interrupt and the motor doesnt die anymore but it still runs very bad and cant get it over 1500 rpm . still idles and revs fine when not under load .

Any ideas ? Bad batch of gas ? or maybe IAC sensor ?