Poulan PP4218AH chainsaw run problem

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  #1  
Old 10-03-18, 04:33 PM
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Poulan PP4218AH chainsaw run problem

Greetings,
I have a nearly unused poulan chainsaw. Started well after a couple of years not used, but only ran for a short time and then shut down. Found that the tube from the filter to adapter was melted away. Took the pipe out, and replaced it completely. Real issue to replace the tube from primer to the fuel tank. Managed to get it through, attached the adapter, and connected the tube with filter to the adapter. Was really proud of myself...…..Duh. Primed the unit, started it and it ran great for 30secs and dead again. Seems that the fuel that is burning is not being refilled into the primer. Read some other posts regarding the path of fuel, and am having a senior moment over and over again. I did not remove the tube that goes from primer to Zama carb, and replaced the line from primer to fuel tank. On the primer, the line to carb is on the short end of the primer, and the one to the tank is on the long prong of the primer. When I pump the primer, it fills with fuel, but after it has run for its 30 secs, the bulb is empty. I have not tested which end sucks and which end pushes, nor changing the connections on the primer. Basically, what causes the fuel to be pulled into the carb, and should the pipe on the Zama carb connect directly to the fuel tank?
 

Last edited by zeeboy47; 10-03-18 at 06:58 PM. Reason: change to question
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Old 10-03-18, 05:45 PM
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Did you try replacing the fuel filter? If the filter is plugged with either dirt or congealed gasoline, the engine won't be able to get enough fuel to keep running?
 
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Old 10-03-18, 07:00 PM
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Did not replace it, but took it off and still no change, so it can not be the fuel filter. In addition, pumping the primer picks up fuel into the bulb which supports the "ok fuel filter" theory. Just want to add that the carb has only 2 pipes on it. One small one goes back to the fuel tank as an overflow, and the other larger one currently connects to the primer. I can not imagine any way that the primer can be set up other than to pull from the tank, and push into the carb. Found this on a repair site, but have trouble to understand it.
Primer bulb (or purge bulb) assembly. The primer bulb draws fuel into the carburetor to make the engine easier to start. The short port on the primer bulb is the inlet. The longer port is the outlet back to the fuel tank.

Given that it says that the short port is the inlet, it make me think that the fuel should go there, but then it says the longer one is the outlet back to the fuel tank. Can't both be right. Lastly with the fuel line plugged into the long port, it fills up with fuel from tank.


Any other suggestions?

My question regarding how the fuel is pulled into carb should get me going in the right direction.
 

Last edited by zeeboy47; 10-03-18 at 07:15 PM.
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Old 10-03-18, 07:33 PM
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This should help. The side of the primer that pushes air out is the one going straight to the tank.
http://i.fixya.net/uploads/images/25...zn1x4l-5-0.png
 
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Old 10-03-18, 08:14 PM
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Cheese,
My Zama carb has only a small tube (from the right side of the carb) going into the tank that is an overflow, and one other inlet for gas. The design you provided is different from my set up. In this diagram, the one in front of the adjustment screws goes to the primer in my set up, and the other seems to be the overflow back into the tank through a very small hole. The bottom pix shows the inlet to the carb attached to the short prong of the primer. The long prong of the primer would go to the tank and filter, and the other outlet from the carb simply drains back into the tank vis a small tube directly into the tank from another hole in the tank.

 

Last edited by zeeboy47; 10-03-18 at 08:34 PM.
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Old 10-04-18, 01:22 AM
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No, you have it connected wrong. The primer output side goes to the tank. The primer suction side goes to the carb.
 
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Old 10-04-18, 01:42 PM
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Finally woke up, and listened to the pros. I was stuck in the wrong gear because when I took the saw into a small engine repair spot, they insisted that I connect the fuel filter to the nipple that holds the purge tube into the fuel tank.

Connected it again as above, and it is now roaring fine.

In all me attempts to make changes, I punched out the small brass filter that is behind the duckbill in the gas cap. Any ideas on where I can get just the brass plug, and not the whole cap? I ask not because I do not want to spend the few dollars for the cap, but I refuse to pay the 10-15 dollar shipping into Canada.
 
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