Odd 462 MT Problem

[jacob j.]

The way it started acting at around 2:31 sounds similar to an MS-200T a member here was having trouble with that they found out had a cracked carb body. So I'm wondering if
something is physically wrong with the carburetor (maybe a casting flaw in the body of the carburetor).

 

[Spladle160]

I think it's got to be getting air somewhere. But why does it go back to idle with a little load? time to run it with the cover off to watch for binding. If there is none start looking for leaks. Maybe spray the carb while it's running.

 

[Hinerman]

But it sounds like it’s pulsing a bit unusually at idle right at the beginning.

I thought the same thing and wondered why Doc did not think it was an issue...

 

[Hinerman]

The way it started acting at around 2:31 sounds similar to an MS-200T a member here was having trouble with that they found out had a cracked carb body. So I'm wondering if
something is physically wrong with the carburetor (maybe a casting flaw in the body of the carburetor).

Could a cracked carb cause the pulsing at the beginning too?

 

[jacob j.]

Could a cracked carb cause the pulsing at the beginning too?

Possibly, if it's leaking enough air. I doubt that's the problem here but there could be some kind of casting flaw. I've never seen a 462 in person
so I'm not familiar enough with the carb configuration to say for sure.

 

[Stump Shot]

@drf256 Have you pressure checked the carburetor?

 

[ferris]

The first 462 came with MT V2.1, but didn’t know if 2.1 saws were send out to the USA

 

[Mastermind]

Al....did you loosen the throttle plate to do any mods to the shafts? Thinning of the plate, or screw heads?

 

[Bjorn]

I dont know if the Carburator are the same But this is a problem to check.

 

[huskihl]

Al and I have both had problems with the 261, but it’s different than this. The 261‘s were overheating due to not being able to provide enough fuel and the M Tronics would shut itself down and prevent full throttle for about 10 seconds until it cooled off. It would then cut fine until it started overheating again. The longer you waited, the longer it would cut fine. Which was what clued us (and TM) in on the overheat issue. This 462 seems to still cut fine wide open when this happens, where the 261 would not. So I don’t think the problems are related

 

[DND 9000]

The MS 462 carb does not have a carburetor with an end cover that includes a air valve like it is built on the MS 362. In the carb of the MS 462 is a baffle plate between the choke and throttle shutter that separates the fresh fuel mix and clean air paths from one another.

 

[huskihl]

I dont know if the Carburator are the same But this is a problem to check.

The problem sounds similar to this, but the 362 has the upper butterfly for fresh strato air and 462 only has one carburetor. The top half is for fresh air and the bottom half gets mixed with fuel.

 

[Stump Shot]

Al and I have both had problems with the 261, but it’s different than this. The 261‘s were overheating due to not being able to provide enough fuel and the M Tronics would shut itself down and prevent full throttle for about 10 seconds until it cooled off. It would then cut fine until it started overheating again. The longer you waited, the longer it would cut fine. Which was what clued us (and TM) in on the overheat issue. This 462 seems to still cut fine wide open when this happens, where the 261 would not. So I don’t think the problems are related

In that case Al, keep diagnosing like any other chainsaw. Once filter and lines are known to be good, pressure test the carburetor at the fuel inlet to 7ps1 if that checks out pressure test the entire saw through the carburetor, block off at the air inlet side and pinch hoses off. Check linkages, wire connections and such. If you can't find anything after searching the saw over, take it to Stihl and have it hooked up to a computer and see what kind of clues it gives.

 

[Mastermind]

The problem sounds similar to this, but the 362 has the upper butterfly for fresh strato air and 462 only has one carburetor. The top half is for fresh air and the bottom half gets mixed with fuel.

That's why I asked if he modded the carb in any way. I've seen a slightly misaligned throttle plate act like this before.

 

[huskihl]

That's why I asked if he modded the carb in any way. I've seen a slightly misaligned throttle plate act like this before.

100% agree. It seems just like that

 

[Cobby08]

Sub'd

 

[Mastermind]

Sub'd

Piss off part timer.

 

[Gary Courtney]

Sometimes a fuel/oil ratio below 50:1 (like 40:1, 32:1) can give trouble, depending on the viscosity of the oil, maybe it`s a possible reason. Also which m-tronic version is this saw? See the version on the front hand guard sticker, circle in the picture. Also what is written on the control unit?
View attachment 225214

run 32-1 in both 462 and 661 no problems

 

[Gary Courtney]

my stihl rep. says they have come out with a newer solenoid that is ceramic inside

 

[Spladle160]

Wonder if Docs home from work yet to see that we've politely typed out 2 pages of instructions for him to get through tonight!