DF200 stalls, will not Idle

[Brtt_mrks]

Hi guys,
Any help would be good.
I have a Suzuki DF200 (2008 I think), the engine has always run perfectly for the last several years and regularly serviced and maintained.
I was recently on the water and had been motoring for a few hours both at speed and at idle. We had stopped and drifted for about 2hrs, started the boat and let it idle for about 2mins before we motored back to our drifting point. As I slowed down to come to a stop I noticed the motor had stalled and thought that was very odd. From than on every time I would try to start it it would turn over and the revs would move up just above 1200 than would stall seconds later.
We checked everything we could while on the water but too no avail. We could get the motor to run by just after starting move the throttle to the forward position with revs, the motor would than run perfectly at revs above 2000. Than any lower it would stall.
We returned the boat to shore and done further tests, checked fuel lines, changed fuel filters and checked oil levels. Temperatures didn't
go above normal either.
We checked the low pressure fuel pump, and the fuel pump when we first turn the key seems to be working.

[redlowrey]

It sounds like an iac problem, but it could be just low battery voltage on crank, these engines do weird things if the battery voltage drops below nine volts. In a car the pcm has built in software to compensate for low battery voltage eg, pulse width for the injectors, dwell for the coils, that is why when you lift the bonnet on a Suzuki vitara you see a battery a third of the capacity of the same size engine in your boat, it's called voltage drop. they don't want the battery voltage to drop below 10 volts on crank. Check your closed throttle position switch too, although it should turn the check engine light on.

[Brtt_mrks]

Thanks for that.
We checked the voltage and had 12v on both batteries.
I was also told to check the white wire that ran from the positive back into the engine computer but that seemed fine and had power.
I took it to a dealer and he plugged it in and come up with no engine fault codes. He seemed to think it was the Idler Control Valve and has ordered one over night. He said the part was about $470. I am now just waiting to see if it fixes the problem.
Thanks again

[Moonlighter]

Yikes! That original Suzuki IAC valve is expensive!

If the same issue comes up again, remember that Mitsubishi supplies the IAC valve for Suzuki and it is a common part on many automotive engines. You you can find both genuine Mitsubishi versions and after market versions available on eBay for big cost savings.