Starter rope hard to pull, can't start saw

[jgyan]

Recently bought a Poulan 3750 chainsaw secondhand. Initially it worked well and it was easy to start. But after taking it apart, and cleaning it, it is now very hard to start. When I try to pull the starter rope it is easy to pull for the first few inches, then becomes very hard to pull, and continues to alternate between easy and hard to pull in time with the pistons motion. With the spark plug removed and holding the throttle the rope is very easy to pull.

The piston and cylinder are both smooth and free of scratches and corrosion. And the starter rope is not damaged and seems to wind correctly.

Looking through some other posts this problem seems to be related to compression and possibly problems with the carb? I also tried leaving the spark plug out to let any fuel in the cylinder evaporate but that did not solve the problem. Any suggestions or advice on what to look at next?

 

[aikensjc]

Try taking the recoil off and moving in a different position

 

[Guido Salvage]

Did you remove or loosen the flywheel or ignition module?

 

[kz1000]

Pull off the recoil and make sure that the rope hasn't slipped out of it's holder and wrapped around the inner piece.

 

[Chainsaw Jim]

It's called compression. Pull harder.

 

[Wood Doctor]

Take the starter housing back off and inspect it. Pull the rope a few times to be sure the mechanism isn't jamming up or if something is caught inside near the recoil spring. If it pulls smoothly when removed, it should work OK on the flywheel.

 

[Agrarian]

Recently bought a Poulan 3750 chainsaw secondhand. Initially it worked well and it was easy to start. But after taking it apart, and cleaning it,...

Can you tell us what you took apart and cleaned to help us with what could have happened? Top end only? Full tear down???

 

[Rookie1]

Did you spray any oil in the cylinder? It seals the rings real good and raises compression.

 

[jgyan]

I've removed the recoil and it works properly, the rope does not get caught or wind incorrectly.

I did not remove the flywheel or ignition module. Also did not spray any oil in the cylinder.

To clean the saw I removed the motor housing, recoil, chain, blade and also removed the clutch (which required some significant force to get loose).

 

[Chainsaw Jim]

Check your bearings. It's possible they're shot and the compression causes the crankshaft to shift enough to lock it up. If they're that bad you should be able to wiggle one side or the other quite a bit.

 

[Agrarian]

With the plug removed and the starter removed, is the saw easy to rotate by turning the flywheel by hand? Do you notice the same areas where it alternates easy and hard?

Where in the rotation does the motion get hard with the plug in (view the motion through exhause port)? Is it at the top of the stroke or at the bottom or other?

 

[Wood Doctor]

I've removed the recoil and it works properly, the rope does not get caught or wind incorrectly.

I did not remove the flywheel or ignition module. Also did not spray any oil in the cylinder.

To clean the saw I removed the motor housing, recoil, chain, blade and also removed the clutch (which required some significant force to get loose).

So, do you still have a problem? Not sure, based on what you wrote. If you do, then there may be a foreign object blocking rotation of the crankshaft that has nothing to do with the starter cord assembly. I once discovered a machine screw inside a Mac 3514 that had broken loose from the oil pump assembly and stopped the piston dead in its tracks and made it impossible to turn over.

The two posts above are also excellent.

 

[Rx7man]

Check to make sure the clutch is on correctly, some models have engagement cogs on the drum that mesh with the oiler, if they aren't lined up it could cause binding.. if the clutch hub spins freely they ought to be meshed right, if it's tight, that could be the problem

 

[aokpops]

I like to bring out the old 298 after it sat about a year an have some one try an start it . I did a compression check about 185 . One thing I notice been running lucas oil it was a pretty normal start after setting over a year . Bought a old lawn boy push mower at a auction for 12 dollars some nut had every one convince the motor was blown . I got home put some gas in it started on the first pull . Just saying good motors pull hard

 

[Westboastfaller]

Not familiar with many models but I have had this happen:
Hairline split in the nylon drum and seperating under load when snaping back to its normal form. It was hard to detect.
May want to pull it apart and try to spread it with your hands? Its a possibility to me.

 

[Agrarian]

I bought a Husky 42 Special recently that was described as needing abnormal amount of force to turn it over and having internal problems. When it arrived I was expecting bad crank bearings but it was nothing more than very good compression. Of course there has to be balance in this world - the 257 I bought was described as being in good condition but it did have obviously bad bearings.

 

[jgyan]

With the plug removed and the starter removed, is the saw easy to rotate by turning the flywheel by hand? Do you notice the same areas where it alternates easy and hard?

Where in the rotation does the motion get hard with the plug in (view the motion through exhause port)? Is it at the top of the stroke or at the bottom or other?

With the plug removed and starter removed it is easy to rotate by turning the flywheel by hand, except there was a hitch at TDC where it was a little bit more difficult to turn.

With the plug in, the motion is difficult whenever the piston is blocking the exhaust port. So both when the piston is moving upwards to TDC, and when it is moving downwards until the exhaust port is open.

Also I did not detect any wiggle due to damages bearings

 

[aikensjc]

There's a 96% chance your saw just has good compression

 

[Guido Salvage]

OP, where are you? Perhaps there is someone close who could look at your saw.