Poulan PP446ET trimmer carb help needed

cprstn54

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Joined
May 24, 2016
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After sitting for six years, Poulan combo chain & string trimmer (split shaft) would lean out and stall at full throttle. I replaced all gas lines, fuel filter and purge bulb. No joy.

I noticed that air bubbles were in the bulb and fuel lines --except fuel feed from tank to carb. I had seen some forum posts that said this should not be.

Ordered up a replacement Zama C1U-W32 carb off eBay. Was a little peeved to see the same air bubble situation. It would appear that this carb lets air into the purge line from carb to bulb.

This eBay carb lets the engine start cold with choke, engine begins to surge and then stalls after maybe a minute. Any effort to open the choke and run at any throttle setting gives an immediate stall.

I have it set up so the feed line from the tank runs to the carb fitting on the same side as the choke lever (120 degree bend, not 90 degree bend).

Any thoughts?

Also ordered a carb rebuild kit off eBay for the original carb, which is my next step.

Ken C
 

bertsmobile1

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Nov 29, 2014
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Firstly you should see some bubbles in the purge line, they come from the pump and allow the fuel tank to pressurise.
The fuel tank runs at around 7 psi so the lines must make a tight seal where they pass through the tank.
So where ever you read that , don't bother going back.
Hand held engines are all about pressure and the tool needed to test them is a pressure / vacuum pump.
You can check the fuel supply by taking the carb off , fuel lines connected turn it sideways and blow high volume low pressure air through it.
You should get a stream of vapourised fuel coming out the engine side.

There are lots of places for the engine to suck in air and run lean
The cylinder base
The spark plug
the crankcase seals
the carb manifold
The impulse line ( if it is not part of the manifold).
 
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