MS200t run problems

hangfirew8 · Jun 24, 2012

Hi all,

You may remember me from my worst-condition-ever for a modern saw post:

http://www.arboristsite.com/chainsaw/198567.htm

Anyway, after a huge quantity of new parts, I've got her running -- sort of. Here's what it does:

Starts easily.

Runs at high RPM great

Idles about 15 seconds and then cuts out.

As an experiment, I ran it at high RPM for a while, it seems to run great, after about 30-45 seconds it cuts out just like at idle.

Goosing the accelerator right before it cuts out has no affect. I can hear a change in tone a few seconds

I thought it was the breather, I removed the brand new breather and blew out the tube with low pressure compressed air, no obstruction that I could tell, no difference in running.

I turned the LA up until the clutch was engaging, and have the L mixture turned most of the way out, tried every 1/4 turn along the way.

The saw doesn't seem to care about mixture, it starts up very easily, two pulls on choke and one on run when cold, one each when hot. It seems to me like fuel starvation and/or clogged vacuum, maybe Stihl sold me a clogged-up new breather? I dunno.

Any hints?

HF

EDIT: More info. Brand new carb, side cover, new spark plug, new handle (both sides), new fuel filter (pickup body), new tank vent (handle side not tank side).The old carb is still stuck to the old broken handle.

jus2fat · Jun 24, 2012

What part is it that you are referring to as the "breather"..??

Do you mean the impulse line..??

Have you removed the spark screen..or at least made sure it is not clogged up..??
(your symptoms sure sound like a clogged up spark screen)

Also..you may just have a bad carburetor..sounds like yours isn't taking adjustments correctly.

These 200t's are known for bad carbs and there must be 6 or more carb models the factory has used.
If you haven't already..I would install a carb rebuild kit before buying a new carb.
:cheers:

J2F

Dan_IN_MN · Jun 24, 2012

WoW! I hadn't checked your previous thread sense I posted. That saw was a mess! Have you had the carb apart? If the mixture screws don't have an effect on the way the saw runs the carb is dirty/plugged up inside and needs to be cleaned or replaced.

hangfirew8 · Jun 24, 2012

Thanks for the quick reply. I'll try to go through point by point. I updated the first post with more background info on new parts.

jus2fat said:
What part is it that you are referring to as the "breather"..??

It is a round thingie with a side mount hose on one side and tiny holes on the other, that fits in the handle alongside the carb, I'm pretty sure the purpose is to allow the tank to breath without leaking gas.

jus2fat said:
Have you removed the spark screen..or at least made sure it is not clogged up..??
(your symptoms sure sound like a clogged up spark screen)

I did, but it is worth checking again, so after you posted I just pulled it out again, then pulled off the whole muffler and blew it out with compressed air. Everything is and was breathing freely. Just as a test I ran it without the spark arrester installed, no difference.

jus2fat said:
Also..you may just have a bad carburetor..sounds like yours isn't taking adjustments correctly.

Hmm. I just ran both H and L back to 1 turn in, and the saw started as easily as ever, then exhibited the exact same symptoms, ran OK at high RPM but died after idling a short while. The only difference is that it sounded a lot leaner/raspier then it did with a few turns out, so I think it is responding to H and L adjustments.

jus2fat said:
These 200t's are known for bad carbs and there must be 6 or more carb models the factory has used.
If you haven't already..I would install a carb rebuild kit before buying a new carb.

J2F

The old carb was a basket case. I got this "new" carb off of eBay, where the seller said he installed it to solve a problem, it didn't make a difference, then he found the problem elsewhere, switched back to his old carb, and was trying to get some of his money back. It does appear brand new... Nonetheless the problem could still be the carb.

HF

jus2fat · Jun 24, 2012

Thanks for the info..

Have you replaced the impulse line..?? If not..then do that..!!

Also..that carb off eBay may be your problem..eBay sellers are not all trustworthy.

I really believe your root problem is some kind of fuel non-supply issue.
:cheers:

J2F

fearofpavement · Jun 24, 2012

If you could find someone with another 200 model saw that is willing, I would try to move the problem from one saw to the other. ie, switch the carbs. If their saw now runs like yours and yours runs fine, then you are onto something. If the problem doesn't "move" then you're chasing the wrong thing.

Did you do a compression check?

Did you change the fuel hoses? (didn't notice that listed)

hangfirew8 · Jun 24, 2012

J2F,

jus2fat said:
Have you replaced the impulse line..?? If not..then do that..!!

I've looked all over the IPL PDF and can't find an "impulse line". Does it have another name? Do you know what page it is on?

jus2fat said:
Also..that carb off eBay may be your problem..eBay sellers are not all trustworthy.

I really believe your root problem is some kind of fuel non-supply issue.

I agree it must be fuel. I figured for $50 for a new-looking carb, if it didn't work I could always rebuild it... it looks like that's what I might have to do.

Thanks,
HF

hangfirew8 · Jun 24, 2012

fearofpavement said:
If you could find someone with another 200 model saw that is willing, I would try to move the problem from one saw to the other. ie, switch the carbs. If their saw now runs like yours and yours runs fine, then you are onto something. If the problem doesn't "move" then you're chasing the wrong thing.

Did you do a compression check?

Only Homelites and such around here.

Only the "turn-the crank, sure does resist a lot" kind.

fearofpavement said:
Did you change the fuel hoses? (didn't notice that listed)

No... I did blow out the vent line... maybe I should blow out the fuel hose as well.

HF

jus2fat · Jun 24, 2012

http://www.arboristsite.com/chainsaw/186964.htm
:cheers:

J2F

morgaj1 · Jun 24, 2012

Could it be the coil cutting out when it heats up?

Zippy · Jun 25, 2012

It does sound like it's running the fuel in the fuel line/carb then quitting - about the right timing. The tank could pressure up enough (due to volatility of fuel) to fill the filter/line/carb but not enough to keep it going of course.

I've never had a 200T stripped down to the cylinder. I had a look at an IPL and there's no impulse line on it.

I guess the carb boot has a channel for the impulse?

You could take the carb off and blow air down the channel with a WD40 straw/bit of fuel line or similar (bottom rhs of the carb boot) and see if it's clear.

redoakneck · Jun 25, 2012

Man where is the love???? That is a pretty dirty deal !!!! Good luck:msp_thumbup:

I will be watching this thread, my bet is the carb, but with all that crap you may have some leaks and poor compression??

hangfirew8 · Jun 25, 2012

Zippy said:
It does sound like it's running the fuel in the fuel line/carb then quitting - about the right timing. The tank could pressure up enough (due to volatility of fuel) to fill the filter/line/carb but not enough to keep it going of course.

I've never had a 200T stripped down to the cylinder. I had a look at an IPL and there's no impulse line on it.

I guess the carb boot has a channel for the impulse?

You could take the carb off and blow air down the channel with a WD40 straw/bit of fuel line or similar (bottom rhs of the carb boot) and see if it's clear.

OK I'll pull the carb (easy enough) and blow it out tonight ( or as soon as I get the chance).

I know everyone is concerned about the compression... this thing starts very easily and runs really awesome for the 20-40 seconds it does run. Even if it is a bit worn, I'm sure it will meet my modest needs - once I get past the runtime problem.

HF

zogger · Jun 25, 2012

No new fuel line and filter? Whut the heck. You could have plugged up a new to you good carb with the old line and dirty tank and filter.

I ALWAYS start with a tank cleaning and new line and filter and clean the carb, any used saw. Running or not. That pic of your saw is nasty, my guess is the previous owner like dropped sludge down it every time he refuelled. Plus, lines just go bad. If you are in the land of just ethanol gas locally, where the saw comes from, the line could look good but be leaking mush into the carb, plus have a hidden crack or something and be leaking air (which also means not getting proper full fuel delivery) plus sucking crud from the tank.

tomdcoker · Jun 25, 2012

Zippy said:
It does sound like it's running the fuel in the fuel line/carb then quitting - about the right timing. The tank could pressure up enough (due to volatility of fuel) to fill the filter/line/carb but not enough to keep it going of course.

I've never had a 200T stripped down to the cylinder. I had a look at an IPL and there's no impulse line on it.

I guess the carb boot has a channel for the impulse?

You could take the carb off and blow air down the channel with a WD40 straw/bit of fuel line or similar (bottom rhs of the carb boot) and see if it's clear.

The impluse port is built in the rubber manifold where the carb. mounts. Check the hole to be sure it is not partically blocked. I have one that I just rebuilf and I have not got it to run as it should. If you need an IPL PM me your email address and I will try to send you one. I am not up to speed on the computer. Tom

hangfirew8 · Jun 25, 2012

tomdcoker said:
The impluse port is built in the rubber manifold where the carb. mounts. Check the hole to be sure it is not partically blocked. I have one that I just rebuilf and I have not got it to run as it should. If you need an IPL PM me your email address and I will try to send you one. I am not up to speed on the computer. Tom

Tom,

Thanks for the offer, I've got the IPL and the Service Manual PDF's already.

HF

hangfirew8 · Jun 25, 2012

zogger said:
No new fuel line and filter? Whut the heck. You could have plugged up a new to you good carb with the old line and dirty tank and filter.

I ALWAYS start with a tank cleaning and new line and filter and clean the carb, any used saw. Running or not. That pic of your saw is nasty, my guess is the previous owner like dropped sludge down it every time he refuelled. Plus, lines just go bad. If you are in the land of just ethanol gas locally, where the saw comes from, the line could look good but be leaking mush into the carb, plus have a hidden crack or something and be leaking air (which also means not getting proper full fuel delivery) plus sucking crud from the tank.

I did mention the new fuel filter in the edit of my first post. I didn't mention it, but I soaked the tank with Sea Foam and then blew out the fuel line with compressed air before fueling it.

A new fuel line is a good idea. I'll get a new impulse and vent lines while I'm at it.

Don't get too hung up on the old picture. Practically all the parts shown are gone now.

HF

hangfirew8 · Jun 25, 2012

Zippy said:
It does sound like it's running the fuel in the fuel line/carb then quitting - about the right timing. The tank could pressure up enough (due to volatility of fuel) to fill the filter/line/carb but not enough to keep it going of course.

I've never had a 200T stripped down to the cylinder. I had a look at an IPL and there's no impulse line on it.

I guess the carb boot has a channel for the impulse?

You could take the carb off and blow air down the channel with a WD40 straw/bit of fuel line or similar (bottom rhs of the carb boot) and see if it's clear.

Hey Zippy,

Thanks for your previous help, you're always there for me!

I read your post and, inspired, this evening I pulled and tore down the carb a bit, there is no tool marks on the screws, the top and bottom diaphragms are supple, and there is no fuel staining. It may be a bad carb, but it's new. I blew out the hole that leads to the impulse line, it seemed clear. I didn't dig down to the needle.

Yes, the intake manifold (which is also new by the way, I sliced the old one in half to get the old broken handle off) has a port for the impulse, which leads to a hose connector on the back of the handle... which I found not connected to the impulse hose. I blew out the hose with compressed air, hooked everything back up and confident I had fixed the problem, started it... it acts exactly the same as when the hose disconnected. How long it runs depends on how long I let it rest between tries. I'm disappointed, I really thought I nailed it when I found that line disconnected.

Next I'm going to buy new vent, fuel and impulse lines, and tear it down again and install them. If that doesn't help I'll buy a carb rebuild kit and try that.

Thanks,
HF

Zippy · Jun 26, 2012

Did you try blowing air through the nipple into the crank case .... and all the other connectors too, as well as the impulse hose?

It could be the tank vent but I wouldn't think it would cause a problem so soon after starting - try running it on it's side with the cap off?

Definitely try a new impulse hose - they're cheap so why not.

It still sounds like an impulse problem to me but I'm no saw tech.

You're nearly there - it can't resist running much longer!

hangfirew8 · Jun 26, 2012

Zippy said:
Did you try blowing air through the nipple into the crank case .... and all the other connectors too, as well as the impulse hose?

It could be the tank vent but I wouldn't think it would cause a problem so soon after starting - try running it on it's side with the cap off?

Definitely try a new impulse hose - they're cheap so why not.

It still sounds like an impulse problem to me but I'm no saw tech.

Thanks, Zippy, last night I did blow out every hose, and tried the cap off thing. In my first attempts there was some vacuum when I pulled the cap off, I seem to have fixed that with all the compressed air somewhere along the way, it no longer does that. I also tried running it with and without the breather thingie on the end of the vent hose both on and off, no difference.

Last evening I found the muffler is not hard to take off, I blew it out and it looks sooo much better after wire brushing. I've not had the gas tank off the engine yet. I ordered the parts at my local dealer today, they should be in next week, I'll replace all the hoses, and I'll check the spark again while hot (I have a Lisle spark indicator, but it is hard to keep connected while pulling the cord), on the off chance it's a bad-coil-when-hot problem.

Zippy said:
You're nearly there - it can't resist running much longer!

I really hope you're right, I'm so close, and it runs so well (while it runs), I'm really getting psyched! I'll hold off on posting pictures until it runs and I get the bar and chain on it.

HF

MS200t run problems

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