Echo chain saw and other chainsaw questions

[oncewaslost1982]

Ok, I picked up 4 chainsaws this past weekend to tinker with. They were all found outside a dumpster. The models are as follows, Poulan 3300 (complete except for air cleaner cover and top engine cover), Echo 452vl, poulan Micro xxv, poulan 2000.

Questions:

1. On the poulan 2000, I can get it to start, only by spraying gas in the carb, it is not pulling from the tank, but it will only run for a second, i have verified that the fuel line is clean and clear of abstructions, and i know it has good compression and spark. The gas cap does not seal really at all so would this be a cause of it not staying running, do 2 cycles need that vacuum in the tank to stay running? I have thoroughly cleaned out every port in the carb. Anyhelp?

2. On the echo, I have tried to get this one to start to no avail. I put a new plug in it and it does get some spark. I sprayed gas in the carb and it still wont catch. I did a compression test on it yesterday, and could only get it to register 75 psi of compression, is this low for a 2 stroke?

3. On the poulan 3300, ok same kind of issue here as with the 2000, i can only get it to start by pouring gas in the carb, there are 2 fittings on the walbro carb for fuel lines, one had a short peice of line running into the tank which i assume is for a fuel retun line? and the other line was missing, so i bought an end of the fuel line filter and some new fuel line and ran it into the tank, it wil start with gas poured into the carb but will also not pull from the tank. It will only run long enough to burn the fuel that is poured in the top of the carb. I replaced both fuel lines with new lines. Any ideas? This one does have a gas cap that seals well. ???


I got the xxv to run by cleaning the carb and it runs great, its a nice little saw and cuts well. So I only have about 1.00 worth of gas and 20 minutes tinkering invested in it.


Any help will be most appreciated.



Thanks, Have a blessed day.


Justin

[Harry]

From my own experience with my Echo, the fuel pickup tube has a weighted filter at its end. This tube is made of a soft flexible rubber so that the weighted end is always at the low point in the fuel tank. After a number of years of use, the rubber tube will rot or become extremely soft and either leak or seal itself shut.

[oncewaslost1982]

but the echo saw will not fire even with gas sprayed in the carb.

[John Newman, Jr.]

If it will not fire with gas sparyed directly in the carb intake, it must not be getting spark. Could be something simple like dirty points (if it has points) a sheared flywheel key or a bad plug and / or plug wire. It could also be a bad ignition module that would cost more than the saw is worth to replace and is why you found it by a dumpster....

[oncewaslost1982]

i know that I am getting some amount of spark, if i hook a test light up to the plug so that the clamp touches the sparkplug leg and diode and ground the negative side of the tester to the engine, I get lights flashing when i pull the engine over. But if i try to ground the plug to the engine and pull it over i dont see much spark?????

[Bill Geyer]

Justin,
Could be on the Echo the spark plug wire is open and having to jump a gap to the connector. This would cause you to have the minimal spark you describe.

As for the Poulans, many things to check, here are some. First the filter at the end of the line in the tank. Most of them are capable of stopping up to the point it won't run. I had much experience with these at work, if you remove it and it dries out it will pass the put in the mouth blow, suck test, but when put in the fuel may not draw The best check is to fill the tank with fuel and with the line free from the carb start a siphon the fuel should flow out or at least very fast drips. Next inside the carb there is probably a very fine mesh screen where the fuel enters the carb. It can be dug out with a pick or pocket knife and cleaned then pushed back in its hole. Sometimes they have so much junk in trapped it is hard to recognize it for a screen. Or many mechanics toss the screen, in that case the carb jets could be plugged. And finally the diaphragm may be hard or porous (hold it in front of a light and look for tiny holes.

Thanks Harry

[oncewaslost1982]

ok I got the poulan 2000 to run, i completely took it apart and cleaned it up, must have had half a cup of old gunked up sawdust and crap all over it. I still could not get it to stay running, So I took the carb off of the poulan xxl and the 2000 now runs great, so this points me to a carb issue with the other carburetor. I have a suspicion that the jets are not set right. Anyone know how to properly set this thing up? I have thoroughly cleaned this carb and it will not keep an engine running. Can someone point me in the right direction. both of the gasket diaphragms look fine, no holes of any sort???? I am confused. What else could be wrong with this thing? Should I just order a new carb? I havent messed with the echo yet, I will update as i get to work on these. thanks for any help.

[Bill Geyer]

Justin, Does the carb supply fuel? Put your thumb over the carb to choke it with the throttle wide open and crank it, your thumb should be wet with fuel, and you should see fuel in the bore of the carb. I forgot to mention the inlet valve, and lever in the center of the carb. Sometimes it can become stuck in it's seat. You can push on the lever and see if the valve moves. You can inspect the rubber tip on the end of the valve with a loupe or strong magnifier. If the tit on the diaphragm is very worn you may have to bend the lever up away from the carb. I don't remember where to begin with the adjustment needles, I would think that one turn out would be a good start. If you hold the throttle wide open and start with an over rich mixture, the engine should four stroke, as you turn the high speed needle in the rpm should increase, if she really starts to scream stop. I usually leave them where they four stroke at a very high speed. Then adjust the low speed needle for best idle. You may have to go back and forth between needles a few times. This may be VERY frustrating The few manuals I have seen with specs said to set the needle lever even with the carb housing. I have found however each has its own likes, bend the lever away from the carb to richen, bend it closer to lean. Do this only as a last resort.

[half-fast]

Check the metering side diaphram to see that it is 100% flexible. If the diaphram is stiff atmospheric pressure cannot move it and the carb. will not function. Another thing to check may be the spark arrester (screen in or on the muffler). If it is plugged the saw may not start and if it does it might idle but not speed up. Remember if you can't get the exhaust out, you can't get the fuel mix in.

[Chisel Tooth]

Hey Justin
Also check and see if the flywheel on the echo has a sheered key these are made into the fly wheel on some units. As was said earlier try a new diaphram kit, if they are stiff at all it won't run.
_ Draw a vaccum on the fuel filter and see if you have any resistance, don't ever blow through a fuel filter to test it. When you blow through you remove any obstuctions that may have been on the filter thus giving you a false result. You reinstall the filter and in a short time the same thing happens again. Remember to flush the fuel tank when you find a clogged or restricted fuel filter.
See Ya
Mike