Poulan 3700, What would cause this???

[dgajr]

I have an old Poulan 3700, which has been a superb saw over the years. Yesterday, after running hard for about 20 minutes, suddenly began missing badly. I could make it run, but not well enough to cut with. I set it aside and continued with another saw. Today, it fires back up just as usual with full power.

It has fresh fuel, new fuel lines, fuel filter, plug, air filter...etc, so I have eliminated most of the really obvious stuff. Any thoughts? Ignition module failing? I would have thought that it would be a go or no go type of failure. Can they be troublesome like a car coil when they get hot and then work perfectly when cool?

Any other suspicions?

Many thanks.

 

[RED-85-Z51]

Id bet on the coil breaking down. Try another new plug though.

 

[highsiera]

coil wire?

maybe coil wire is a bit frayed and rubbing on the casing? When it was missing, were you bucking or was the saw on it's side?

 

[dgajr]

I had been bucking... a large pine. Maybe the 20th consecutive cut, so the saw had been cutting upright the entire time (no change in position when it happened).

 

[highsiera]

poulan

sounds like ignition rather than a seal, a bad seal seems to show itself when the saws flipped sideways.. let us know what you find after you go digging.

 

[Freakingstang]

could be the coil, could also be a spun flywheel. Take it apart and see if the flywheel has moved on ya, before you go buying a new coil.

 

[dgajr]

Thanks,

Will do on the flywheel, I'll check it out. But I'm doubtful about it... It ran perfectly today with no effort to repair...etc.

Is there a way to test the existing coil?

 

[Justsaws]

Warm up the saw until it stops running and then hook up a spark checker or unscrew the existing plug, hook up the coil to it and ground the plug to the saw. Pull the saw like you are trying to start it if you can see good spark then it may not be the coil.

It sounds like a spark issue. An additional way to check would be to warm the saw up until problem occurs and to put a different plug(same type) with the gap set at .015 in it. If the problem goes away or is less severe than it is the coil.

 

[milkie62]

I have 2 3700 Poulans: One had a cracked fuel line that ran funky at times and the other had loose carb bolts that also ran funky---check those 2 areas

 

[lawnmowertech37]

the best way to tell if a coil is bad is if the unit runs fine while running cold then it starts acting up when hot thats the time to check your compression and also the color of spark when a engine is warmed up this can pin point either coil or cylinder problem hope this helps out

and if its the coil that will be a obsolete coil part # 530-039093 yes we have them if you need to find one you wont have very far to locate it