2006 DF115 - Could IAC Be the Problem?

[JohnTN]

I have a 2006 DF115 four stroke on a pontoon boat with only 135 hrs. It was cutting out sporadically at higher rpm last year and mechanic suggested running 100% gas and Seafoam in it. It has slowly improved and last week, after running a little rough for 10 minutes, it ran well to 5500 rpm.

I brought it back to dock and shut it down. Five minutes later I cranked it and no fire. This has never happened before. I finally got it started by pumping throttle in warm-up to WOT a couple of times. But sputtered and died.

Over past week I have tried to start it a few times and got a few sputters. Once it started by moving throttle to WOT and idled smoothly at 1500 rpm for a couple of minutes before I shut it off. Next time it just cranked and wouldn't start.

Could a dirty or bad IAC cause this?

John

[catacom225]

IAC valve

Hi John
I would say no to the IAC,It would be giving a 3-1 error code, A lot must be considered and you will need to give people a little more info,like
Have you checked and changed all filters [ high and low pressure ]
Inspect VST Tank
How long between changes
Have you inspected your tank breathers
Have you tried running on a separate tank with 91 oct not premium
Im not sure if 06 has the engine holder corrosion issue and so on, then theirs the electrical side, you should start from the batteries up to the helm pulling every connection apart inspect and clean
Check some of these items off,and let us know

[JohnTN]

Without a computer/scanner, is it possible to detect a 3-1 code by a flashing light on the tach?

[Muskykris]

Without a computer/scanner, is it possible to detect a 3-1 code by a flashing light on the tach?

When mine went it didn't throw a code until I unplugged it.
it was the check engine led on the tach
Flashed 3 times... Paused and then flashed once

[JohnTN]

2006 DF115 Rough Running, Hard Start Solved

2006 model with only 130 hrs on it. I thought it might be the IAC, but mechanic pulled plugs and they were pretty fouled with oil. Replaced all 4 plugs and it starts, idles, and run to WOT at 5,500 rpm smooth as silk.

Sometimes its just the basics. But with only 130 hrs and fuel injected I didn't think the plugs would be a problem even though they had never been changed. He suggested changing them every 2-3 years even if low hourly useage. And only use ethanol free gas.

John

[Moonlighter]

Id agree with that. An annual service, change engine oil, and check and clean plugs (and change every 2nd year regardless of hours), drop the leg to change gear oil and inspect impeller and same as plugs, change impeller every 2 years regardless.

Plus, i am assuming that you are running a good Racor style water separating fuel filter in the lines? Really is essential on modern 4 strokes, unless of course you enjoy the enxpense of replacing fuel filters in the engine and having the injectors cleaned every year or so! We change Racor filter elements every year, regardless of hours.

Just one other comment - if 5500 is the max rpm you can achieve, you are still a bit over-propped. These motors will run best and deliver best economy at cruise speeds if they are propped to achieve 6000rpm at WOT.