Suzuki DF200AP will not idle

[Tony64peter]

Hi All from NZ. 2022 DF200AP 98 hours, maintenance iaw. Suzuki service manual plus annual oil and filter changes. 4 weeks ago after 5min running engine coughed and died.
No fault codes. Engine will start then after about 6 revolutions dies. Fuel system meticulously checked multiple times, rail pressure a constant 36psi, ALL sensors checked multiple times, compressions 160 psi x 4, new plugs and injectors, voltage to ECM 12.7v. The engine will run sweet if I squirt fuel into TCM, I've taken rpm up to 3000 using throttle lever and small squirts of fuel.
My thinking is that either the ECM is getting a bad data input after the auto start sequence and trimming back the injector pulse duration OR the ECM is faulty.
I took the boat back to dealer whom sold me the motor. 10 days in they can not find the fault using their SDS and replicating all the troubleshooting I have done. $$$$ warranty is only for parts. They state that these ECM's never fail. Current status we are awaiting test equipment from Suzuki to check the ECM.
Have any forum members experienced something similar and could advise the resulting fix?
Kind regards Tony

 

[99yam40]

Not a Suzuki guy, but I would think the injector rail pressure would be higher than 36 PSI.
is there a electric high pressure pump inside the VST?

 

[Tony64peter]

Manual has rail pressure at 36psi and regulator releases at 38psi. These engines are not HPDI. The injectors are upstream of the inlet valve. Cheers T

 

[99yam40]

OK, thought they normally ran higher.
saw Yamaha runs 38 to 40 and Mercury 58 to 60

 

[Tony64peter]

My boat has been with the dealer coming up to 1 month and they have consulted Suzuki NZ and Japan and it is no closer to being diagnosed than when I delivered it. $$$$$ Wishing I had bought a Merc.

 

[JustJason]

If the engine will run at a higher RPM, and stay running at a higher RPM, but not idle, it's usually the idle air control valve, which regulates the engine's idle speed. Have to connect the engine to the scan tool to be sure, though.

 

[Tony64peter]

If the engine will run at a higher RPM, and stay running at a higher RPM, but not idle, it's usually the idle air control valve, which regulates the engine's idle speed. Have to connect the engine to the scan tool to be sure, though.

Hi Thanks for your kind intentions. This is a digitally controlled engine, ie no manual push pull cables. It has no IAC. SDS that I refer in original post is Suzuki Diagnostic System a bit like OBD 2. There are no fault codes. According to the SDS all sensors and ECM serviceable. Suzuki Japan have no answers when evaluating the data. The dealer, although having tested all sensors is now planning to replace all sensors and loom one by one to see if that rectifies the fault. $$$$$$$. At 68years old at the time of purchase I was convinced this would out last the rest of my boating life with out hassles. How wrong was I.

 

[99yam40]

Hi Thanks for your kind intentions. This is a digitally controlled engine, ie no manual push pull cables. It has no IAC. SDS that I refer in original post is Suzuki Diagnostic System a bit like OBD 2. There are no fault codes. According to the SDS all sensors and ECM serviceable. Suzuki Japan have no answers when evaluating the data. The dealer, although having tested all sensors is now planning to replace all sensors and loom one by one to see if that rectifies the fault. $$$$$$$. At 68years old at the time of purchase I was convinced this would out last the rest of my boating life with out hassles. How wrong was I.

are you sure?
I thought all injected motors controlled the air and the injector on time to get them to run at idle properly

 

[JustJason]

are you sure?
I thought all injected motors controlled the air and the injector on time to get them to run at idle properly

I took a look. OP is right. On this specific engine, there is no IAC; the idle is controlled by the electronic throttle body.