Ongoing MS290 trouble

[dallypost]

My MS290 has given me trouble for several years. I am convienced that the trouble is carboration. I have to go through the carb once or twice a year just to keep it running. When it is running, I like the saw just fine. My brother has the same saw with easially twice the numer of hours on it and he has never had the carb off.

Getting ready to start getting firewood and my saw will not start, no suprize. Removed carb, disassembled, cleaned reassembled and and fired the saw up. I tuned the carb as follows:
1. L and H one turn out.
2. Started the saw and adjusted LA until chain started to move, then backed off slowly until chain stopped.
3. Closed L until the saw started to die (lean). Opened L 1/2 turn.
4. Opened H until the saw started to burble at full throttle.

The saw idled for ten min. without a hickup. Made a few test cuts, everything seemed fine. Shut the saw down for about 10 min. Since the saw was hot, I tried to start it with the switch in run position. Each pull of the rope resulted in 5 or 6 half hearted pops and then the saw would die. Choaked the saw for one rope pull and their was nothing. Went back to run and still nothing. Assuming that I flooded the thing, I went to full throttle with the switch in the run position and pulled 20 or so times, nothing. This happened once last year and after several days of trying to start the thing, I went through the carb again, it ran fine for a few cords before it set in again.

I have a new fuel line, new fuel filter and a freshly cleaned air cleaner.

I visited the local chainsaw shop. They have two replacement Walbro carbs. One costs about $30 and is the same thing I have now, I think. The other is three times the money.

Do I need a new carb and if so, is it worth the extra money to get the upgrade carb.

 

[jus2fat]

I think you have your L screw too rich..at idle..go right until 'slowdown'..then left until 'S-D'..then set in the middle.

I was gonna suggest carb kit..but if you can get a New adjustable carb for $30..that's the way I'd go..!!

J2F

 

[dallypost]

"I think you have your L screw too rich..at idle..go right until 'slowdown'..then left until 'S-D'..then set in the middle."

What do you mean by S-D?

Actually, I have put several carb kits in this carb. The reason I didn't this time is because the current carb kit has less than ten hours on it.

 

[jus2fat]

"I think you have your L screw too rich..at idle..go right until 'slowdown'..then left until 'S-D'..then set in the middle."

What do you mean by S-D?

Actually, I have put several carb kits in this carb. The reason I didn't this time is because the current carb kit has less than ten hours on it.

By 'S-D' I meant slow down in engine speed same as with turning clockwise...that would mean right..lol..

I think your carb is done for and time to replace..!! - your call..!!

J2F

 

[AKDoug]

The last item you need is a new impulse line. I've seen them fail just at the ends where they plug into the carb. They get a little loose nipple and you won't even know it.

 

[dallypost]

I am looking at carbs online, $18.00 and up. What should I be looking for.

 

[watsonr]

One that fits... nothing else to look for really.

Where in Idaho you from?

Carb here with free shipping 1127 120 0650

 

[discounthunter]

did you actually install a new carb kit or just clean and reassemble with the old parts?

 

[dallypost]

You got me wondring about the impulse line. After letting the saw sit for a few hours, I chocked it and it fired up after a few pulls. I went to half choke and got nothing. I pulled the plug. It was dry. Turned the saw over and no gas ran out. I put the plug back in, went to full choke and pulled a bunch of times. I figured that if everything was working, the beast should be really flooded. The plug was still dry and inverting the saw produced no gas.

The impulse line at the carberator end looks good and feels soft. No cracks are apparent. The line disapeares through an orange bulkhead, what dies the other end connect to. Are they difficult to replace?

 

[griffonks]

No, you remove the handle to access the impulse line. It's possible to vacuum/pressure test the whole saw including the impulse hose.

You have to block the intake and exhaust, then pressure test thru the impulse hose. This will not tell you if the impulse orifice is loose at the carb.

Put a few drops of fuel mix in the carburetor venturi and see if it fires.

 

[Terry Syd]

Take a small zip-tie and put it around the rubber nipple of the impulse line that the carb pushes into. Tighten it up just enough so that you can still get the carb back on. I did it on one 029 and it cured the air leak.

The other end of the impulse line is on a barbed pipe on the cylinder. It is fairly well sealed, so check the junction with the carb. If you want to find out if the line itself should be replaced, try a piece of fuel hose from the cylinder barb to the carb, it's easier to work with (especially through the plastic cover).

 

[watsonr]

Squirt some fuel down the throat. If it runs, its a fuel issue. If it don't, you got other problems.
Soft fuel line/impulse is not always a good thing, no cracks is the goal, they may no be apparent. Even a carb just sitting exposed to ethanol for several months takes a toll on the rubber internal components, installing a kit would be recommended if you haven't or a new carb if that's an easier way for you, it would eliminate any carb issue.