Stihl MS880 runs at high idle then dies.

[chad556]

Well so far I have:

The ms880 powerhead: $650
Piston kit from ebay: $35
Bar and chain from baileys: $90
Carb kit from ebay: $13
084 Carburetor from ebay: $40
Fuel filter from ebay $8
Gasket and seal kit from ebay: $35

Total money in the saw thus far: $871

I think thats everything as far as parts and accessories, i bought a few new tools too.

Flywheel puller: $40 (could probably sell it now)
t27 driver to reach the cylinder head screws: $5
Brake bleeder kit to vacuum test: $20
hydrocloric acid to clean out the jug: $10
Tachometer: $20

So there is another $95 worth of tools to add to the collection :smile2:. Man, i love tools.

Overall not such a bad investment. I would guess i could at least get my money back if I sold it on ebay or craigslist. Just the other day I saw a near brand new ms880 that was siezed go for over 1000 on ebay. I think after what I have been through with the baby i will want to cut some wood with it first though. In fact i am off to attempt just that. If it doesnt work out I guess I will be taking it to the shop on monday though. I at least want to get a new fuel line that goes between the carb and the tank. That thing is stiff and the clip is so warn out and weak that i would put my money on that spot being an air leak if there is one especially under vibration. I want to fix it just for peace of mind.

 

[gink595]

I think posting on this thread has jinxed me:hmm3grin2orange: I went out and put a bar and chain on mine and now I think I have carb problems....fark me!!! I swear me and these HT carbs just ain't meant to be! I wonder if a 3120 carb would fit up?

 

[fearofpavement]

IF there was a way...

If you could find anyone close to you that has a running 880, it would be very interesting to see if your carb would run on their saw and vs vs. I have had very weird mechanical problems with different things in the past and finally only resolved them by finding a clone of it and playing musical parts until I was able to move the problem from one piece to the other.

ie, if your saw runs with a known good carb, then you know that's the problem. If it doesn't run well, but the other saw runs fine with your carb then you know the carb isn't the problem and so forth.

You had the flywheel off, was your woodruff key in good shape?

 

[showrguy]

hey chad,
just watched your video, when the saw shut off at the end i thought we were going to see a sledge hammer smashing on it !!!
if you can't find a for sure good carb i'd be willing to take mine off and send it to you to try, just to be sure it's the carb.... i know my880 is good to go...
you gotta promise not to mess with it though....he,he,he

 

[chad556]

If you could find anyone close to you that has a running 880, it would be very interesting to see if your carb would run on their saw and vs vs. I have had very weird mechanical problems with different things in the past and finally only resolved them by finding a clone of it and playing musical parts until I was able to move the problem from one piece to the other.

ie, if your saw runs with a known good carb, then you know that's the problem. If it doesn't run well, but the other saw runs fine with your carb then you know the carb isn't the problem and so forth.

You had the flywheel off, was your woodruff key in good shape?

Thats good advice, if i had followed that months ago i'm sure it would have saved me a lot of work lol. I have actually played musical parts with two carburetors and I think the key now is to keep playing it. I am going to look closely at the metering diaphragm and make sure I have the best one in there. I think i will also switch out my current fuel pump diaphragm (gold one) for one of the black rubber ones that I have. It might just be incompatible with the fuel i'm using. Also, the key was in good shape on the flywheel and went back in without a hitch, good point though, that would throw the timing off some...

I took it for another test run today and Brad was right, just a little richer on the L screw and it purred away indefinitely with some fine tuning. At that setting however I could not rev the saw up at all. I would hit the gas and get a gurgling sputter and then the engine would stall. I gave the H screw a few adjustments from a half turn to 2 full turns and the best i could get it was around the 1 turn range where it would gurgle and the chain would spin at half speed (i would guess around 4k to 7k rpms). After a while the saw got harder and harder to start and felt like it was flooding so I put it back on the shelf for the day. When i turned it on its side i could hear the gas leaking out of the muffler and sizzling on the cylinder. This sounds just like river rat's diagnosis to me and I will be going over that diaphragm and everything near it.

So my game plan for tomorrow is to:

replace the fuel pump diaphragm with the best black one i have.

double check and see if my metering diaphragm and related parts are working as they should.

go to the shop and get a replacement for my fuel line. probably not the problem but its another possible issue i can prevent. I am having doubts that it is sealing effectively against the little plastic elbow fitting at the top of the carb.

repeat my process of tuning it and hope for the best, if no luck there then i will probably have to finally just take it in to be looked at. When i'm there tomorrow I will try to pick the guys brain and see if he has any experience with these kinds of carbs, hey you never know.

Oh and Showrguy, lol, you know if I had been wearing my steel toed boots i probably would have contemplated booting it across the driveway and selling the salvageable parts on ebay :hmm3grin2orange: Seriously though, thanks for the offer on the carb. I think i have the problem narrowed down pretty well now. Every time I mess with the carburetor i get different results so that seems like a good sign. Hopefully one of my little tweaks works out but I will let you know if I want to try one out thats good to go.

Thanks for all the input guys, you've helped me out immensely. I will be sure to let you all know how it works out!

 

[Blamo]

I am in suspense

What happened? I know that this is an old post but, I am new to the site and have been following along like I am reading a good book. This ending is terrible. Does Chad move away from the city to pursue his dreams of starting a logging company? Does he finally get the girl? More importantly, did Chad get that dang saw working?

 

[bgreen]

I have a 390 that is having a problem at high rev runs up good then starts to stall out, but it will idle all the obvious things have been done rebuilt carb checked top end and crankcase pressure no holes in any of the lines checked out the torque on the cylinder bolts tried a brand new stock ignition still the problem persist. Looked at the cylinder there is some light scoring below the exhaust port and a very little above the intake port it is not flooding but there seems to be a lot of excess fuel in the cylinder. To much dirt ingestion replace the top end?

 

[fearofpavement]

Sounds like a fuel issue. Try switching carbs with another saw. (there's a lot of these around, find a buddy to see if you can move the problem)

Is the fuel hose an aftermarket one? If so, that could be the issue as most don't work properly (they pinch off on this model saw)

I just had a similar problem on an MS390 this afternoon. It would cut great about halfway through a 12" log and then bog down. I pulled the carb, cleaned it, slightly tweaked the metering lever height and put it back together. Runs great now.

 

[fearofpavement]

The above applies primarily to the Stihl MS390. If you meant a Husqvarna 390, some but not all is applicable.

 

[bgreen]

Thanks for the response it is a Husqvarna. Had a friend tell me the same thing about the carb issue, gonna try that it has a new stock fuel in it but I will check it for a pinch.

 

[bgreen]

Dropped in a new carb bingo back in the run. Again thanks for the assist.

 

[Maintenance supervisor]

Plastic fuel inlet is always bad.

 

[laro4444]

Thats good advice, if i had followed that months ago i'm sure it would have saved me a lot of work lol. I have actually played musical parts with two carburetors and I think the key now is to keep playing it. I am going to look closely at the metering diaphragm and make sure I have the best one in there. I think i will also switch out my current fuel pump diaphragm (gold one) for one of the black rubber ones that I have. It might just be incompatible with the fuel i'm using. Also, the key was in good shape on the flywheel and went back in without a hitch, good point though, that would throw the timing off some...

I took it for another test run today and Brad was right, just a little richer on the L screw and it purred away indefinitely with some fine tuning. At that setting however I could not rev the saw up at all. I would hit the gas and get a gurgling sputter and then the engine would stall. I gave the H screw a few adjustments from a half turn to 2 full turns and the best i could get it was around the 1 turn range where it would gurgle and the chain would spin at half speed (i would guess around 4k to 7k rpms). After a while the saw got harder and harder to start and felt like it was flooding so I put it back on the shelf for the day. When i turned it on its side i could hear the gas leaking out of the muffler and sizzling on the cylinder. This sounds just like river rat's diagnosis to me and I will be going over that diaphragm and everything near it.

So my game plan for tomorrow is to:

replace the fuel pump diaphragm with the best black one i have.

double check and see if my metering diaphragm and related parts are working as they should.

go to the shop and get a replacement for my fuel line. probably not the problem but its another possible issue i can prevent. I am having doubts that it is sealing effectively against the little plastic elbow fitting at the top of the carb.

repeat my process of tuning it and hope for the best, if no luck there then i will probably have to finally just take it in to be looked at. When i'm there tomorrow I will try to pick the guys brain and see if he has any experience with these kinds of carbs, hey you never know.

Oh and Showrguy, lol, you know if I had been wearing my steel toed boots i probably would have contemplated booting it across the driveway and selling the salvageable parts on ebay :hmm3grin2orange: Seriously though, thanks for the offer on the carb. I think i have the problem narrowed down pretty well now. Every time I mess with the carburetor i get different results so that seems like a good sign. Hopefully one of my little tweaks works out but I will let you know if I want to try one out thats good to go.

Thanks for all the input guys, you've helped me out immensely. I will be sure to let you all know how it works out!

How this woked out ????????I am having same issue, read all those post and ..........please let us know ?

 

[keepreal]

Ok so today I went out to pursue a great find on CL, a nice ms 880 for $650 (I was set on finding a 660 for that price). The guy said the reason for the low price was that the saw would start but would not idle, it would just rev up to half throttle, sputter and then quit, I figured simple enough just a little tweaking and I could get it running strong again, probably a carb issue. Well, the whole story was that he took it to his local stihl dealer and they told him that the piston and clyinder were bad, causing the saw to rev up fast when it was started instead of idle like it should. This seemed kind of strange to me, the saw obviously has decent compression (nearly ripped my fingers off trying to start it) The dealer told the guy $700 to replace the piston and cylinder to get the saw running again.

Probably against my better judgement I shelled out the cash anyways and took the saw home. Cleaned it up, cleaned the carb and started experimenting with the High Low and Idle screws. No luck, the longest i got it running was about 20 seconds and it wildly revs up and down, It wont go down to idle when i take the trigger off and when i go to full throttle the saw only goes up to ~1/2 to 3/4 throttle at best and then "pulses" (sounds like somethings going to break.) I don't have a bar and chain for it, all of mine are 3/8" and dont fit on the bar studs. I am getting a 36" carlton one from baileys. Is there anything about this that seems wrong to any of you? (I admit I am a novice when it comes to tinkering with chainsaws) Could it really be the piston and clyinder are bad? I wouldnt think it would fire at all if that were the case? Im stumped and I dont want to spend more money or make a bigger mess than i have to, can anyone give me a place to start or point me in the right direction?

Hey,buddy,you can check on ***********.They might can give you some help.

 

[STIHLMECHANIC]

impulse line..has a hole in it

 

[RajElectric]

I'm having the same issue on an 088, holds vac and pressure all day, good compression, clean P and C, recond carb, fuel line holds vac and pressure, runs high idle then dies lower RPMS. I have a coil on order.

 

[PP4218]

Thats good advice, if i had followed that months ago i'm sure it would have saved me a lot of work lol. I have actually played musical parts with two carburetors and I think the key now is to keep playing it. I am going to look closely at the metering diaphragm and make sure I have the best one in there. I think i will also switch out my current fuel pump diaphragm (gold one) for one of the black rubber ones that I have. It might just be incompatible with the fuel i'm using. Also, the key was in good shape on the flywheel and went back in without a hitch, good point though, that would throw the timing off some...

I took it for another test run today and Brad was right, just a little richer on the L screw and it purred away indefinitely with some fine tuning. At that setting however I could not rev the saw up at all. I would hit the gas and get a gurgling sputter and then the engine would stall. I gave the H screw a few adjustments from a half turn to 2 full turns and the best i could get it was around the 1 turn range where it would gurgle and the chain would spin at half speed (i would guess around 4k to 7k rpms). After a while the saw got harder and harder to start and felt like it was flooding so I put it back on the shelf for the day. When i turned it on its side i could hear the gas leaking out of the muffler and sizzling on the cylinder. This sounds just like river rat's diagnosis to me and I will be going over that diaphragm and everything near it.

So my game plan for tomorrow is to:

replace the fuel pump diaphragm with the best black one i have.

double check and see if my metering diaphragm and related parts are working as they should.

go to the shop and get a replacement for my fuel line. probably not the problem but its another possible issue i can prevent. I am having doubts that it is sealing effectively against the little plastic elbow fitting at the top of the carb.

repeat my process of tuning it and hope for the best, if no luck there then i will probably have to finally just take it in to be looked at. When i'm there tomorrow I will try to pick the guys brain and see if he has any experience with these kinds of carbs, hey you never know.

Oh and Showrguy, lol, you know if I had been wearing my steel toed boots i probably would have contemplated booting it across the driveway and selling the salvageable parts on ebay :hmm3grin2orange: Seriously though, thanks for the offer on the carb. I think i have the problem narrowed down pretty well now. Every time I mess with the carburetor i get different results so that seems like a good sign. Hopefully one of my little tweaks works out but I will let you know if I want to try one out thats good to go.

Thanks for all the input guys, you've helped me out immensely. I will be sure to let you all know how it works out!

What was the final outcome?

 

[JosephSalesky]

Dudes, same problem with my 880. What was the outcome?

 

[Dennisthemenace]

Air leak