Ms290 post rebuild flooding...

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Skunkdynamite

ArboristSite Lurker
Joined
Sep 20, 2019
Messages
37
Reaction score
45
Location
In between saws
I'm sorry if this is redundant, searching through the threads there's a ton of people who have messed up their saw during the rebuild process... And a very disappointing 9 part youtube video

I got it for $40 someone straight gassed it. The rest of the saw is in great shape.
I put a meteor 390 P&C in it and opened up the muffler. Used Genuine Dirko on the bottom end, replaced the fuel and impulse lines with OEM too... I had Rebuilt the carb in the process, everything was fairly clean and free from corrosion to begin with besides the sticky gasket. I replaced the needle and spring and tried adjusting it several times, but it keeps flooding. (I have an oem replacement carb in the mail)

I just got a second to fiddle with it and took the carb off and the fuel is trickling out while it's disassembled. Spark plug is out, carb is off. Puddle of fuel on the bench! I also tried running it with and without the tank vent and cracking the fuel cap.... Same thing runs for a few seconds then floods out.
What could I possibly have messed up to get this bad of a flooding problem? I had this problem with my Harley and I fixed it by adjusting the needle height.
 
If you're going to work on 2-cycle engines, your best purchase is a mityvac pressure/vacuum tester. It sounds like you inlet needle is leaking. Could be a dirty seat, bad needle, maladjusted metering lever, incorrectly installed gasket/diaphragm. Applying 7psi to the fuel inlet would confirm.

It's common for people to get the gasket/diaphragm in the wrong order on the metering side which causes flooding. Gasket against the carb body then diaphragm.
 
I found a schematic on here with the correct gasket sequence. I also tried both new and old needles and metering levers at the level height. I am kind of ham handed when it comes to these tiny pieces... I have the mityvac setup, I'll try the metering lever again and do a pressure test.
 
I found a schematic on here with the correct gasket sequence. I also tried both new and old needles and metering levers at the level height.

What would you describe having the spring arm at the "level height". The carb case body or the recessed well. Just checking...;)

When you rebuilt the carb and used new parts, is the button on the diaphragm that pushes the needle arm the same length?
 
What would you describe having the spring arm at the "level height". The carb case body or the recessed well. Just checking...;)

When you rebuilt the carb and used new parts, is the button on the diaphragm that pushes the needle arm the same length?
Put a straight edge across the whole thing and the arm should just clear it by a fraction. Also clean the seat with a Q tip and check to see how it works.
 
Lol! New carb on the way... I adjusted the metering lever so that it's just a hair clear of a straight edge.
What would make the fuel keep flowing with the Carb removed though? I left for a few hours to work on the car, came home and it's sitting in a puddle! Bad saw! Do I whack it with a newspaper?
 
Got the new carb in the mail, she's running like a champ. Really appreciate the help
The 390 is replacing a burned up 291. Came up cheaper that way for me if free time is really a thing... Took a while to get it done right, but worth it!
Last year I had 1 chainsaw and it blew up... Now I have 6 funny how That happened.
 
Great that you got it going with a new carb!

... So you could not tell what was broken, worn out inside of the old carb? Some of us learn and what to know that information why it was flooding for future like problems. Thanks.
 
Great that you got it going with a new carb!

... So you could not tell what was broken, worn out inside of the old carb? Some of us learn and what to know that information why it was flooding for future like problems. Thanks.

Looking back on my order for the parts I did not get an OEM rebuild kit. I'm going to suspect the needle/ metering lever is NFG Chinese junk right out of the box. Lesson learned the hard way.
I really have no way to tell, but the new oem one did the trick.
For my next trick I think I'm going to do a 170 to 180 rebuild. I really enjoyed this little project. (Despite the carb snafu)
 

Latest posts

Back
Top