Saturday, October 17, 2015

Poulan 2050 Chain Saw -- Carburetor Diaphragm Replacement

Hard starting, and failure to idle/accelerate, are symptoms of a stiffened carburetor metering diaphragm. Use of ethanol-laced gasoline makes diaphragm stiffening inevitable after a few years of service.

Following is the procedure for diaphragm replacement on a Poulan 2050 chain saw. (The carburetor shown here is a Walbro WT324.)

1) Top Cover Off

Loosen off three captive No. 10 screws (T25 Torx recess) to free the top cover. The cover comes away easily.

Note the pinched spark plug wire. Someone was careless once when reinstalling the top cover, and pinched the wire's insulation quite badly. Fortunately, the wire's conductor is undamaged, and the wire still functions.

2) Air Filter Element Removed

3) Air Filter Housing Removed

Two M5 flange nuts (8mm A/F).

That gets you to where the carburetor is unfastened. Note the following:

- Choke Pull

Don't try to free the blue choke pull from the choke lever plate. Just slip the choke pull's grommet out of its notch. The choke pull can remain attached to the carburetor throughout this job.

- Fuel Lines

There are two to be disconnected.

The upper one is fuel supply from the left side of the fuel tank.

The lower one is primer suction from the rearmost primer bulb nipple.

- Throttle Link

With the fuel lines disconnected, you can manipulate the carburetor so as to disconnect the throttle link.

4) The Carburetor Off The Engine

5) The Pump Side

A single 8-32 x 3/8" pan head screw fastens the pump cover in place.

Note that the diaphragm goes to the body of the carburetor; the gasket goes to the cover.

6) The Metering Side

Four 4-40 x 1/4" pan head screws fasten the metering diaphragm cover in place.

Note that the diaphragm goes to the cover; the gasket goes to the body of the carburetor.

Note also that there's a small extra hole in the cover aside from the screw holes. That hole must be clear of debris, and open to the atmosphere, in order for the metering diaphragm to function.

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1 comment:

  1. Hi - I'm trying to fix my Poulan 2050 chainsaw (it looks the same as yours) which has two brittle fuel lines, which I've removed in pieces. I can order more however I'm having trouble identifying where the thicker line came from/goes to - I don't see this thicker line in your images above and because it broke immediately as I pulled the air filter housing off I couldn't see where it attached inside. Does your chainsaw have this thicker line? And how does it attach to the primer? Thank-you.