Poulan Pro PP5020 won't start

[VRR.DYNDNS>BIZ]

Remove the spark plug and shine a light into the spark plug hole looking at the exhaust port with the piston in the down position. Any cylinder damage and you are done. Or you can remove the muffler but sometimes the mounting bolts will break off and look at the side of the piston, but the spark plug hole is easier

Also if the muffler is plugged no air flow/exhaust will flow thru. Also you say the compression feels right - but pull it over slow. If is has very little resistance the cylinder leakage is not good. At a slow pull the compression should not leak off overly significant, at a fast pull it will seem to have compression. The problem if slow pull leaks off is not so much compression but air fuel bypassing the rings back into the crankcase and having nothing to fire.

 

[bertsmobile1]

I am a Poulan fan and have about ten + of the cheap saws - the Quality of the spark is important - clean flywheel and make sure the mag. is set right - (I use an alluminum can as a spacer gauge - check to make sure you have a good spark by pulling plug and spinning engine with plug attached and grounded. Strong blue white spark should be present. Often a new flywheel and mag will be needed and if you shop around you can get a kit cheap - about $15 - Also check that you crankshaft bearing does not have too much -or any play . -Good luck - don't throw it out but save it for parts! Usually these Poulans need the gas lines changed as well - if you cut a sliver off the end of the line then you can put the line in the hole - grab the remaining sliver with needlenose pliers and pull the gas line through - these gas lines are a common problem with most all saws - good luck to ya !

Please go to the attic , find the box with your old high school books in it and read the chapter on magnetism & electricity.
Magnetic flux is not effected by rust dirt oil grease or just about any other material sitting on the surface
Remember playing with iron filings a magnet and a sheet of paper.
On top of that mechanical work as in scrubbing with a wire brush will reduce the magnetism by altering the surface microstructure of the alloys used to make magnets.
All magnets loose their magnetism over time , it is called magnetic decay because being a magnet is a high energy state, remember the first law of thermodynamics ?
What is important is the gap between the magnet & the pick up as it affects the timing of the spark and the intensity

 

[bad69cat]

Consumer grade saws have no cylinder liner.... so its raw aluminum. You MUST let them warm up at idle for awhile before going to full throttle! Otherwise the side of the cylinder closest to the exhaust valve heats up way faster than the other side and it scores the cylinder. If you warm them up first you can avoid the issue, even if it runs a bit lean..... but running a tad rich is always the way to go. You can get a compression tester for free at some parts stores (just a refunded deposit) if you want to do a quick test.

 

[Bellcrank]

My saw hasn't run for a while. The issues started when I was cutting up a fairly large hickory tree that fell. The saw started getting dieing after it got hot. Later it wouldn't start at all.

So here's what I've done and checked:

Changed the plug, fuel filter, air filter, carburetor, and ignition coil.

Low and high adjustments are about 1-1/2 turns from seated.

I occasionally get a single pop when I pull the cord.

The plug has spark, there is fuel on the plug when I take it out.

I don't have a way to check compression but it feels right.

I drained and replaced the fuel.

I pulled the fly wheel and the shear pin thing is intact.

Can anyone offer any advice?

If the muffler bolts are frozen a quick test is use'n liquid compression. ( motor oil ) through the spark plug hole. Does not take much oil to fire a worn piston / cylinder combination.

 

[virtual_guy]

OK. I took this thing apart and replaced the cylinder, piston & ring. I followed a VERY good tutorial on the subject here:

>> tutorial video <<

So now I have replaced every fuel component but the tank, the plug, ignition coil, air filter, carb, cylinder, rings, piston.

It still will not fire once.

I looked at the plug when jumpered to the cylinder head and it has spark. It appears to be getting fuel.

So here's the only thing I can think of. In that video he runs a bead of gasket maker on the crank case where the shaft bearings seat (at 20:20 in the video). I failed to do that but I also noticed that there was none there when I took it apart. Is that a normal thing to do and could it be causing enough of an issue that it wouldn't hit at all?

Otherwise I'm at a loss.

 

[ILENGINE]

You would think the rubber material around the bearings would seal those areas, but maybe they don't conform correctly causing an air leak. Did you put sealant on the mating surface around the cylinder base.

 

[virtual_guy]

You would think the rubber material around the bearings would seal those areas, but maybe they don't conform correctly causing an air leak. Did you put sealant on the mating surface around the cylinder base.

Yes I did. Loctite 515

 

[virtual_guy]

I picked up a tester and verified that I have plenty of compression (around 135 psi). I'm running out of ideas here.