MS 462 issues

[Mark_Skyland]

Well I've hit a brick wall with this one. A dreaded intermittent fault. The machine is less than a year old and only has a round 6 hours of use.

Basically the saws runs really strong but all of a sudden it will run like the choke is on, overfueling, spluttering and wont idle. It can then after a couple of starts and a bit of a rev run fine.

First off changed the spark plug, solenoid, performed a reset along with a tank, filter clean etc which I thought fixed it as it ran good for me but then failed again with customer. Next time around it was a carb carb inspection, vac/pressure test, fuel line and carb pressure test, loads of compression but I did pull the exhaust to find nothing but a clean looking piston. Checked all wires and connectors HT lead spark plug boot but found nothing. It was running fine and it and I couldn't get it run poorly. Customer took it away and then came back with it a week or so later! It was running well for most of the day he used it but when he got back to the yard to cut up some timber it started playing up again. I had to buy the stihl diagnostics kit and after getting it all set up it came up with no faults as the machine was running fine again.

 

It has to be the coil or the carb but I thought I would throw this out there in case anyone has a better idea or has seen this issue before.

Any help would be very much appreciated.

 

 

[Dan Maynard]

If I read that right, you haven't managed to get it to run poorly after doing work on it.

 

Can you rule out fuel by getting him to run on Motomix?

[Muddy42]

I'd check and clean the carb again.  Then I'd use the saw and bit and see if I could get it to replicate the fault again.

[spudulike]

Have you checked the AT wiring is OK and also given it a stretch when checking? The MS201CM has a habit of fracturing or wearing the wiring under the top handle front AV mount and that can give similar bad running.

I haven't used the Stihl AT software but is the machine setting the high and low fuel settings correctly? Not sure if you can see this info but sometimes the tests on Husqvarnas CST test with no faults found but the fuel settings can often be interesting.

[spudulike]

Another thought....I once had a 372 XPT that had been round 3 dealers with a farting mid range which was a bit on an off.

Anyway....the long and short was that the generator behind the flywheel had come loose. I haven't had a MS462 in so am working blind but the IPLs look like it has a generator fitted. Worth checking out the tightness and wiring. 

[Mark_Skyland]

Thanks for all the suggestions.

I ruled out bad fuel as he only uses decent two stroke and it was the same fuel when it was running well in the workshop. 

I've checked all the wiring and connectors, no issues. I even tried wiggling and poking all the wires while it was running.

No generator Spud, just the coil which I've replaced today going out well since the issue. I was logging some timber with it for about 15 mins and it ran well.

 

The Stihl diagnostics is a lot different than the husqvarna setup. It doesn't record faults or show the carb settings. It basically checks the electrics then you can run it up while still connected and it performs a re calibration and does a couple of other checks.

 

I had it plugged into a ms500i that wont start, it' came up with no faults on that one too. 😀

 

[spudulike]

So the Stihl AT software isn't quite as good as the OBD2 port on your car then

 I took a look at the IPL again and the generator was for the heated handles - I thought it strange as the Stihl AT machines I have worked on have used two magnets on the flywheel to generate the AT power.

Lets hope it is the coil, I hate it when you have to resort to swapping out parts like you have had to, I much prefer a charred fooked up part that is definitely causing the issue.

[Mark_Skyland]

7 minutes ago, spudulike said:

So the Stihl AT software isn't quite as good as the OBD2 port on your car then

 I took a look at the IPL again and the generator was for the heated handles - I thought it strange as the Stihl AT machines I have worked on have used two magnets on the flywheel to generate the AT power.

Lets hope it is the coil, I hate it when you have to resort to swapping out parts like you have had to, I much prefer a charred fooked up part that is definitely causing the issue.

I haven't had a lot of time on the diagnostic kit but I can certainly think of plenty of other things that I could spend £500 on!

Yep, I don't like swapping out parts when I'm not sure that its causing the issue, it will be nice £80 hit for me if I'm wrong. If the coil doesn't work then I'm swapping the carb, if that doesn't work then, well I'll cross that bridge when I get there.