Stihl MS170 - No Fuel

[SteveSr]

Hello,

This saw originally came to me with a master control lever problem which was an easy fix. Unfortunately, it sat around a while and when I tried to start it got no fuel (dry spark plug) I assumed the carb was gummed up and put in an OEM kit. I also found a nearly obstructed spark screen.

After putting everything back together. Still no fuel so I primed it with a little gas in the carb throat and it started right up. I let it warm up a while and went to put it in some wood. At first it acted fuel starved then something clicked and it started to run normally. This tells me that the carb kit was installed correctly. I cut with it a little bit then shut it down , drained it , and ran it dry.

Fast forward to today. Refueled it but no start. Spark plug dry. No fuel again. Taking the air box off I noticed that the choke butterfly was not closing all the way. I don't know if this is normal or not or is a possible cause of the no fuel issue. This may have been part of the master control lever issue.

However, I am beginning to think that this issue is caused by the screwy manifold/impulse arrangement in this saw causing an impulse leak. It has a hard plastic ring in direct contact with hard aluminum carburetor. It is not hard to imagine a leak here if things aren't just perfect. The manifold does have a little deformation which looks like it has been there forever but it is on the opposite side of the hole from the pulse port. I can't believe that Stihl didn't put a real gasket in there.

Anybody have any other ideas or how to fix this?


Thanks,

Steve

 

[Rockjock]

Hello,

This saw originally came to me with a master control lever problem which was an easy fix. Unfortunately, it sat around a while and when I tried to start it got no fuel (dry spark plug) I assumed the carb was gummed up and put in an OEM kit. I also found a nearly obstructed spark screen.

After putting everything back together. Still no fuel so I primed it with a little gas in the carb throat and it started right up. I let it warm up a while and went to put it in some wood. At first it acted fuel starved then something clicked and it started to run normally. This tells me that the carb kit was installed correctly. I cut with it a little bit then shut it down , drained it , and ran it dry.

Fast forward to today. Refueled it but no start. Spark plug dry. No fuel again. Taking the air box off I noticed that the choke butterfly was not closing all the way. I don't know if this is normal or not or is a possible cause of the no fuel issue. This may have been part of the master control lever issue.

However, I am beginning to think that this issue is caused by the screwy manifold/impulse arrangement in this saw causing an impulse leak. It has a hard plastic ring in direct contact with hard aluminum carburetor. It is not hard to imagine a leak here if things aren't just perfect. The manifold does have a little deformation which looks like it has been there forever but it is on the opposite side of the hole from the pulse port. I can't believe that Stihl didn't put a real gasket in there.

Anybody have any other ideas or how to fix this?


Thanks,

Steve

That ring was the bain of a weeks worth of misery for me several years back. I removed it and used a clamp from a 024 and never had an issue since. Also the more I ran my 017 ( MS170 ) the better it ran.

 

[SteveSr]

That ring was the bain of a weeks worth of misery for me several years back. I removed it and used a clamp from a 024 and never had an issue since. Also the more I ran my 017 ( MS170 ) the better it ran.

These low end consumer Stihl saws are just plain aggravating to work on!

I don't see how an 024 manifold would work on this 170. Isn't the pulse port separate on an 024 (just like an 026)?

After I wrote my original post I decided to go out and look inside the carb for signs of fuel. Much to my surprise there was fuel in the carb! So this may not be a pulse issue after all.

So now I am back to the reason why the choke shutter is not closing properly. I am beginning to wonder if the previous user "adjusted" i.e. bent the linkage wire. That is a stiff wire to bend! I can't really see any other reason for the choke not closing all the way.

Steve

 

[Rockjock]

These low end consumer Stihl saws are just plain aggravating to work on!

I don't see how an 024 manifold would work on this 170. Isn't the pulse port separate on an 024 (just like an 026)?

After I wrote my original post I decided to go out and look inside the carb for signs of fuel. Much to my surprise there was fuel in the carb! So this may not be a pulse issue after all.

So now I am back to the reason why the choke shutter is not closing properly. I am beginning to wonder if the previous user "adjusted" i.e. bent the linkage wire. That is a stiff wire to bend! I can't really see any other reason for the choke not closing all the way.

Steve

No no not the manifold the ring/clamp that attaches the intake manifold to the cylinder. I was at my wits end. Rebuilt the carb and same issues once I changed out the clamp it all worked well. I can take off the air filter housing and have a look to see if mine closes all the way or not.

 

[o8f150]

just get you a wt215 carb and it will take care of the problem

 

[1Cut]

Wt 215 will fit with some minor adjustment.. Like the impulse hole in the carb is in a different spot. I just converted one a week ago.

 

[Rockjock]

Seems like the OP said it was not the carb but the manifold. I have had saws like that once I give them some mix in the carb they come to life and keep going. My stock 017 butterfly does not close all the way either. But I know after I did the rebuild I ran it a fair bit and on the 2nd tank there was no hint of an issue at all. I am thinking the good gas and the stihl oil worked their magic in the carb. I had posted a vid of it ripping thru some seasoned oak like bubba at a pie eating contest.

 

[Chris-PA]

I had posted a vid of it ripping thru some seasoned oak like bubba at a pie eating contest.

You mean it puked?

 

[SteveSr]

No no not the manifold the ring/clamp that attaches the intake manifold to the cylinder. I was at my wits end. Rebuilt the carb and same issues once I changed out the clamp it all worked well. I can take off the air filter housing and have a look to see if mine closes all the way or not.

Alright, I can see how a clamp could fix a recalcitrant loose manifold at the cylinder. I guess that plastic retainer ring is cheaper than a steel clamp.

 

[SteveSr]

Based on my findings last evening of gas in the carb and it will start and run if primed the only thing left is the choke butterfly. There is a small bypass hole in the choke butterfly which seems to indicate that it should be closed all the way when engaged. I guess I'll have to try to rig the carb without the air box to test this theory. I can't think of anything else right now.

Steve

 

[Rockjock]

You mean it puked?

Projectile vomiting of wood chips ahuh you betcha!

 

[SteveSr]

Well, I made some spacers to take the place of the air box on the mounting bolts. I put everything back together and found that the choke was definitely not closing all of the way. I then carefully bent the choke arm rod ever so slightly until the choke closed fully. After this the saw started right up like a Stihl should!

So it looks like the lesson here is that if you have an 1130 saw (017, 018, MS170, MS180) that is hard to start this would be a good first place to look for an issue. It is surprising how critical this choke linkage is.

Steve

 

[anlrolfe]

What some don't realize is that the lever works in conjunction with the throttle. From what I recall, in choke you can flip the lever into high idle when you get it to pop but to go to normal idle squeeze the throttle/trigger. If you manually flip the level to go from high to normal idle it hangs up on the internal workings. If you force it you can bend the linkage or break the internal trigger/throttle parts. My ms180 is actually a 2nd hand toasted 170 that received a Chi-con long block and adjustable carb.