Twins DF175A both running rough

[Solarman]

I'm thinking along the same lines moonlighter... some connection (probably around #2 coils?) may have pulled loose, during oil change? For both motors, relating to identical problems?

Likewise, "if" forum is still working?

[blbaker88]

I checked all plugs and electrical connections. I also swapped coil packs and spark plugs with another cylinder and nothing changed. The coil pack and spark plug worked when moved to another cylinder. I delivered it to a Suzuki certified mechanic. I'll post the solution, hopefully soon...

[blbaker88]

Just wanted to provide an update…this one has Suzuki stumped, not just my local mechanic but Suzuki. They have checked compression, fire, fuel, swapped wiring harness, swapped ECM, and still same failure. Maybe this is premature, but does anyone have any ideas on my options when the motors under warranty aren’t, or can’t be repaired? Given today’s modern outboards and especially Suzuki, I am am, well I don’t know what to think. Hopefully next week Suzuki pulls a rabbit or in this case two rabbits out of the hat.

[Moonlighter]

Warranty is nearly always repair if possible, if that isnt possible, then replace.

No different than if the engines blew up.

So they have had the regional technical representative involved ?

[redlowrey]

Mate I can understand this problem might have you and your local mechanic stumped, for suzuki to say it has got them stumped, did they send the janitor who cleans the toilets to go and have a look at it. The technology for these engines have been out there for forty years, except for the variable valve timing on the intake cam.
You should be able to establish yourself whether the computer is shutting down spark and injection pulses, or something has happened and effected the compression.

If you can do a compression test yourself and note if the computer is shutting down the injector, the plug will be clean and dry and the other three will be dark in color. I will guide you on what to check and how.

[blbaker88]

Yes the regional Suzuki Tech is involved. The latest they tried was to swap out the wiring harness. At this point I am at their mercy waiting for them to get to the next item on the list to swap. I am supposed to hear more next week.

[blbaker88]

Another update...Local Suzuki mechanic has now changed out the boat wiring harness, no effect. The Suzuki District Tech is supposed to have been out to assist. The local mechanic says everything he has tested indicates these engines should be operating flawlessly. For now, the time to repair is indefinite...

[artdf175]

Are your engines wired with the interface cable to get readouts on your MFD ??

[blbaker88]

I met with the mechanic today. He believes he has found the issue. He found the port engine had jumped time. Reset the timing and he said engine now runs fine. He plans to do same to starboard next week. So asked what can cause both engines to jump time. He reluctantly told me ha had a suspicion. He suspected running the boat aground could cause this to happen. Perhaps he is correct. However, in this case that absolutely did not happen. So now I am not sure I can ever trust these engines again. What else can make twin engines at 200 hours jump time within in a few seconds of one another? Then as another blow, the adjustment and troubleshooting hours may not be covered under the Suzuki Extended Protection Plan.

[Moonlighter]

Can you be more specific please about what is meant by “jumped time” and exactly what the mechanic found and corrected?

Is he saying that the timing chain had jumped a cog, or something else?

It seems too incredibly coincidental that this happened to both engines immediately after an oil change/service.

[blbaker88]

I believe he indicated one tooth. The more I think about this the less I am comfortable with the diagnosis. The odds are just too incredible. And both engines briefly ran fine after the oil change.

[Moonlighter]

Agree sounds very odd and far too coincidental. Hopefully they are properly fixed.

I hope you dont get charged….

[blbaker88]

Well, we are back to square one...Mechanic now has indicated adjusting time made no difference on one engine and moved issue from #2 to #4 on the other. I suspect it did not jump time. So we are back as reported by the mechanic to spending hours of try this try that...In the meanwhile, summer is zooming by and my boat is not available.

So if anyone has any idea no matter how unlikely or ridiculous sounding, please share!

[Harper]

You're sayng no fire on #2 on both engines. I assume you mean no spark on those #2 cylinders. And it's definitely #2 on both engines? How did you determine that? Have you checked the fuel flow and spray pattern of the injectors?

[Solarman]

This might be an odd thing but it could affect both engines.

You have two pick-ups for fuel on the same (common) tank? With same fuel, maybe it is more stale around the pick-ups near bottom?

Do you know if each pick-up has an anti-syphon valve at the outlet of the tank? Is it possible that both might be (assuming you have them - installed from factory, I'm guessing) jammed up/ gummed up affecting fuel flow to each motor? This could happen at about the same time?

Just thinking outside the box for commonalities, most of us thought of fuel problems in the beginning?

And I don't think Both motors jumped timing, but as Red said the V V Intake Timing was the new difference for many years?

Anyway, best of luck, post back on what you find out.