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Hi everyone. I have a Poulan Pro pr624es. My engine has been surging or hunting I believe are the terms...it idles up and down when the choke is off. Acts fine when choked.

Did some research and all signs pointed to needing to clean the carburetor. Took it completely apart and cleaned everything - sprayed with cleaner, sat parts in carb cleaner bath, ran needle through each pinhole opening and cleaned everything with small wire bristle brush...THOROUGH! Put it back together - no difference.

Since then I have done the following
-New spark plug
-Removed the fuel line checked for clogs - it's clear
-Removed the shutoff valve under the gas tank - cleaned the barb and whole valve assembly.
-Removed the fuel filter from the shutoff valve assembly - cleaned it.
-Cleaned the inside of the gas tank the best I could - gave most attention to the opening where the shutoff assembly connects.

No change. I'm stumped. I feel like everything is cleaner than when I bought the thing new lol. Is there someone that can point me in a direction I have not considered? I feel like there is adequate fuel making it to the carb, but it's not getting to the engine. I tried hitting the primer once or twice as it was surging/hunting and it did make a difference...so somewhere in the process, there is not enough gas.

Thank you in advance!

-Steve
 

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Wow, sounds like you touched all of the bases. If it were me, my next step would be to but a Chinese carb. Or, have you tried fresh gas ?
 

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Just for the heck of it, try running it with the gas cap loose to see if maybe the vent is blocked. Don't actually clear snow that way, just run the engine full throttle and see if there is any improvement with the cap loose.

In the meantime, until you have time to possibly replace the carb, if that's turns out to be the problem, run it with a little choke so it behaves nicely while you're working it.
 

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You could have an air leak between the carburetor and where it mounts to the engine's intake. That can allow "raw" air in, making the engine run lean.

If the carb's float was sitting too low, that might be able to contribute.

Cleaning the main jet again might not be too much effort, and could help, if it's still restricted somehow.
 

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Sometimes you just can't get the carbs clean. Hopefully they make a Chinese knockoff cheap, and just replace the carb. To check for a vacuum leak spray carb cleaner around the carb to engine joint while running.
 

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With everything done and suggested, sure sounds like it's running lean to me. Check any carb you look at to see if it has adjustable jets in it (preferred IMO). I know some have drilled out jets in other engines a little to resolve this same type of issue when there was not an adjustable jet available. The other idea would be to see if there's an adjustable replacement jet available for your machine.


Just some thoughts.
 

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You don't say how old it is but I'm guessing it could be time for a new carb. If you can find a replacement carb with either/or adjustable idle and main jet you're golden. I put a carb with an adjustable idle jet from a Husqvarna on my Cub Cadet with a 208 cc Powermore engine with minimal modifications. An adjustable main jet needle from waterlooboy2hp completed the process and it runs better than new.
 

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how does it seem to run when it hits the snow and how long have you had the machine? only reason i ask is my neighbor has a machine that does the same thing when idling but when it hits the snow it seems to smooth out. i know i mentioned it to him a few winters ago that it sounded a bit off but i think i have heard a few other blowers since that do it.
 

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Some people say it's worked for them. I've tried Seafoam in 2 engines that needed choke to run smoothly, neither one showed a benefit.

For one, after running gas + Seafoam, I even tried to fill the bowl with what was pretty much straight Seafoam, and let it sit for a few days. Then ran gas again, and it still needed choke. It ran great after running it through the ultrasonic cleaner, though.

There's definitely no harm to trying Seafoam, but it hasn't produced a lot of results for me. Put differently, even if it doesn't fix the hunting, you might still be dealing with a dirty carb.
 

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The hunting comes from partial clog in the low speed part of the carb.

I use Berryman's carb dip, let it sit for 4 hours, then put it in an ultrasonic cleaner. After that I use a set of welding tip cleaning wires. The latter has a rough section on it that acts as a reamer.

I've used 3 different carb dips and found the Berryman's to be the best so far. The best Berryman's in the 5 gallon pail is a different chemical and much stronger than the 1 gallon.

What carb dip did you use?

I realize everyone does not have access to an ultrasonic cleaner but they have worked where the dip alone has not. On the older Tecumseh carbs there is a Welch plug on the side that needs to be removed to clean the holes behind it. I don't think your carb has such?

I recently did a neighbor's Chinese engine carb on his Craftsman that has been hunting for couple of years. I told him to use Seafoam but he waited until the night of the snow storm when it didn't start to put another carb on it only to find it was the wrong one. A few day later I did his snowblower, after the soak and ultrasonic cleaner it ran so smoothly.
 

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A few day later I did his snowblower, after the soak and ultrasonic cleaner it ran so smoothly.
Curious, have you tried just the ultrasonic, without the chemical dip beforehand? I'm sure you've cleaned way more carbs than I have. But with the ~5 that I've done, I've just run them through the ultrasonic (heated to about 140F, typically for an hour), using Simple Green HD, no other chemical pre-soak, and all came out running great.

Just curious if you've had cases that didn't get clean using just ultrasonic, and definitely needed a chemical soak as well.

Sorry KLSRC, I know this is sliding a bit off-topic for your thread. But it came up during the discussion, and got me wondering.
 

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when you use those chines carbs are the jets different from the ones used in snowblowers? that is do you have to enlarge the main jet?

on this carb, i am wondering if there is a idle jet also that needs to be cleaned or passageways in the carb body.
 
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