DF 115 Troubleshooting Query

[XCasper]

So I don't have every detail in front of me now but I'll answer as best I can any follow up questions.

We have what I believe to be a 2002 DF115. (will verify with serial chart I just downloaded) When first installed it ran very poorly and a call to someone said we had wrong control box for a 4-stroke. This season we now have what we believe to be the right box but still running bad. Better but not even close to good enough.

Motor will start, wouldn't idle at first but now does, will shift into gear OK but if you apply throttle it stalls immediately. After much fiddling we discovered that we could very slowly advance throttle (in either direction) in small increments and after a delay the rpms would catch up at which point we could then advance another increment and so forth.

After launching and applying this technique they got her up to a max of about 3200rpms but she would surge.

We have a Sierra STATS system which when hooked up tells us very little except there are no errors reported. I'll follow up tomorrow with an attachment of the report I did generate.

Finally decided to go to a dealer but there is no Suzuki dealer within a 5 hour drive of us that has any diagnostic equipment better than we have in this STATS system.

Only other thing I recall is we did add sea foam, we're using premium 91 octane fuel, through the STATS system we were able to manually drop out each cylinder and injector one at a time but that didn't appear to resolve anything.

That's what I know. What else can I say to help someone advise here?

Thanks for your time.

[XCasper]

More info

If I performed the attachment correctly there is a PDF file of a report from the STATS system. The two live data snapshots are a day apart and the second one is with seafoam in system but nothing else had been changed by us.

[aquamort]

Following as interested to know too. I can only suggest basics at this stage:

Check fuel pressure. Check MAP sensor is not blocked and is clean. Neutral switch (will only rev to 3000rpm if thinks is in neutral). Whats the timing doing? Check sensor connectors and connectors in general including at the battery.

As you say it doesn't make much difference when you knock out a pot at a time I wouldn't think its compression or spark? More of an engine control issue is my guess ie sensor/s or a switch. Good luck.

[PaulinFL]

Did you ever find your problem? Im having some of the same issues with my df60. It bogs and surges and 2500 rpms. I'm at a loss and was curious about your results.

[Moonlighter]

On the early DF90-140 series, there is a corrosion issue in the engine holder that you will want to check. It can cause these kinds of symptoms because it lets exhaust gas into the cowl and the engine chokes on its own exhaust. Also, if left untreated the hot exhaust escaping can damage engine wiring, which causes all sorts of problems.

Where to look? Easy!

On the port side, about 2" below the fresh water flushing port. You'll see a round plug in the engine casting, looks like a welsh plug. The corrosion occurs around the outer edge of this plug. You will probably need to take the lower engine covers off to get a good look at it.

It may not be the cause of your current problem but it's highly recommended that you check it out and monitor it in future regardless.