Author Topic: Poulan PP4218a wont run right  (Read 237 times)

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  • pruner
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Poulan PP4218a wont run right
« on: January 08, 2014, 09:19:57 pm »
I work on small engines every day, but cant get this thing to run right ,good compression,carb clean, but if i get it idling good it bogs at throttle ,can adjust it to run wide open then it wont idle , usually pretty good at carb adjustments, havent found any air leaks, appreciate any advice.

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Offline fossil

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Re: Poulan PP4218a wont run right
« Reply #1 on: January 08, 2014, 09:56:02 pm »
It sounds like a carb issue. How far out do you have the low and high needles?
Is the metering lever level set right and are you sure the diaphragms and gaskets are in the right order?

Offline 3000 FPS

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Re: Poulan PP4218a wont run right
« Reply #2 on: January 09, 2014, 12:29:46 am »
I agree with fossil here.   I have found when the high and low needles are set they are usually pretty close to one another.   You might try and kit the carb or just get another one.   I can not imagine a new carb would cost very much.
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Offline fordfairlane78

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Re: Poulan PP4218a wont run right
« Reply #3 on: January 09, 2014, 01:01:35 am »
I don't know what the technical term for them are but are the sealed caps that cover the h & l venturi underneath the diaphragm leaking? I have had a similar problem on stihl grass trimmers and this was the issue. ...could someone educate me on what these caps are referred to as?
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  • pruner
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Re: Poulan PP4218a wont run right
« Reply #4 on: January 09, 2014, 01:30:53 am »
Had them from o to more than three out its a new saw , got it for free hate to have to buy carb for , got to many saws now ,just keep for parts rather spend a few $ on old Homelites or Mccullochs

Offline sharkey

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Re: Poulan PP4218a wont run right
« Reply #5 on: January 09, 2014, 08:55:36 am »
Some ideas of where to look;
i. Leaking welsh plug-leaks fuel into the venturi from the metering chamber, usually on the low side.  Check the service bulletins to see if anything is mentioned.
ii. Worn out or stretched diaphragms-use the walbro kits which handle the ethanol better than the aftermarket offerings.  If you get a year out of the kits anymore your doing good.   
iii. Leaking high speed check valve nozzle-usually shows itself as the carb just wont hold a tune.  Lean one minute, rich the next.  Wont idle right but will run good at full throttle.  Air leaks through a worn high speed nozzle's check valve system and down into the metering chamber  A bad high side nozzle check valve never leaks fuel, always air.  More and more of the carbs are not repairable because the labor rate exceeds the value of new.  These nozzles can also clog refusing to flow fuel. 

For extended warranty purposes some new carbs are coming with high side nozzles that are of the semi-fixed jet type.  These nozzles draw 50% of their fuel straight from the metering chamber rather than through the adjustable high side jet.  These nozzles are susceptible to varnish because theyre so small.           

Double check your metering lever height.  Do you have access to a carb 'thumb pump' so you can run a few tests to rule out a leaking inlet needle or a worn or bad inlet seat?     


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