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Discussion Starter #1
I'm very pleased to find this forum nd will appreciate any input. I have a Poulan Pro 25 cc trimmer that is about 3 years old. We used it lightly for 1 season and then it has set up for about two years. I took it to a local repair guy and he said it couldn't be fixed, but I know he detests two cycle engines and I decided I'd try to get it running.

I first replaced the coil as it didn't seem to be firing. While doing this, I decided to replace fuel filter and fuel lines as they had some age on them. When it would not start, I decided I'd replace the carburetor and see if that might get it going. I have reviewed countless you tube videos. I bought an ignition tester which shows I'm getting fire to the spark plug. I bought a compression tester which shows I'm getting good compression. You tube videos suggested a plugged spark arrestor so I took the muffler off and tried starting it with no muffler, still the same results. I have removed the muffler now twice and have yet to find a spark arrestor???

I have another trimmer which is a craftsman that looked like it was on it's last leg. Had been sitting for probably 10 years. Not having any luck with the later model Poulan, I decided I'd try my luck with it. I cleaned the fuel tank which was mostly blue oily liquid, put in fresh gas, pumped the primer bulb about three times and it came to life and ran great. Surprise!!!

It had the same spark plug as the Poulan, so I exchanged the plugs and the craftsman still ran just as it did with the original plug. I noticed it has the same carburetor and I switched carbs, the craftsman ran perfect and the Poulan still refuses to start. I managed to get it to start and run roughly for a few minutes, but it will not rev and when pressing the throttle, it will die. After it runs for a few seconds, I've removed the spark plug and it is wet with fuel which indicates it is getting too much fuel.

I'm baffled as to what may be the problem. I have the tenacity of a bulldog and I would be much better off in terms of time and money to just go buy another trimmer, but.......that means I have let this little Poulan trimmer get my goat....I am hoping some of you guys with much more expertise will help save my pride.... I will be very grateful... Look forward to your responses...

Nick Williams
 

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Nick,
Conditions that could cause your trimmer's symptom:
Plugged exhaust
Scored piston/cylinder
Carburetor leaking / set too rich / collapsed diaphragm (i.e. flooding)
Very worn piston/cylinder
Stale fuel
No spark

Suggestions:
Ensure your mix is fresh and proper ratio.
You indicate it has good compression. What was the reading? 120 lbs. would probably be the bottom value and still have it run.
Inspect the exhaust, or even try running it without the muffler. Mud wasps favor muffler outlet pipes in Autumn here in NJ.

Also, a 2-stroke's entire crankcase, including crankshaft seals are part of the intake system, any leaks could hinder or prevent operation. A bad leak could also provide the wet-plug symptom. You'd need to block off the intake and exhaust and use a miti-vac to test the CC. You'd be getting into a new level of home-repair. I have old posts out there that illustrate how to perform such tests and how to make your own block-off plates.

BTW "Poulan Pro" is an oxymoron.
Paul
 

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PaulR44:

Thanks so. such for the reply.

I've removed the muffler and tried to start, so I don't think that is the problem. Its been a couple of days since I check the compression, but I think it only got to 90, so I'm going to double check that.

So pleased to check back on this site to see a response.. Thanks again. I'll look for your videos about blocking off the system and checking...

Most appreciated
 

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You absolutely cannot simply see that a carb is the same number on two devices and then swap it to think it will work fine on both. A carb that is the same on say motorcycle or car will have the exact same jetting, that is NOT the same on a chainsaw as the carb may be the same but adjusts wildly different on the two devices and the difference in one starting and one not. The major jetting adjusts there and may need super rich on the Craftsman but then be wildly flooded to foul the plug on the Poulan.

Pull the muffler and check out the cylinder walls for damage, Poulan does it very easy and damaged will be much harder to start. You may not be able to identify the spark arrestor feature, sometimes it is only in more convoluted muffler flow path that does it.
 

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I realize it's been over a month but in case you check back.....

In the interest of being thorough, you can also check the flywheel key (likely molded in as part of the flywheel). You can have all three elements of combustion (compression, fuel, spark), but if the spark happens at the incorrect time, it won't fire. When you pop the flywheel off, you'll know right away if that's it or not as it will look "fubarred" ;-)

FWIW! Good luck!
 
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