I have a 6.5hp briggs on a poulan pro mower. The coil will spark a few times and quit, spark and quit.

[moodymac]

The diameter is the same, but the cooling fins are much taller and pronounce on the Poulan vs the Murray and would not allow for the top cover to be refitted. Besides, the customer is picking up the Murray soon.

 

[moodymac]

And are you sure the blower housing with the model number on it belongs to the engine it is on.
More than once I have been caught out because the covers had been swapped and what was under the hood was not the original engine.

Yes, both are original.

 

[moodymac]

According to the numbers you posted they both use the same flywheel. Seeing you have two different flywheels, have you checked to see if everything is exactly the same? Magnet location in relation to key slot.slot, Flywheel diameter, Magnet size, etc. As stated I think you’ve found your problem

Yes, the only visible difference that I can see are the cooling fins. I have a couple of locked up Briggs engines, tomorrow I will check the flywheels and try replacing the one on the problem engine.

 

[moodymac]

Get a compass, a real one with a swinging needle, not your phone
Sit it on top of the coils & slowly rotate the flywheels ( check both engines )
I am hazarding a guess that the magnets on one have reversed or are compromised
As the flywheel passes the compass , the needle will swing either N ( showing the magnet is south out ) or S ( showing it is north out ) or will swing showing the magnet is orientated length wise ( not usual ) .
You can get a very rough measure of the strength by moving the compass back and seeing how far away the flywheel moves the compass needle
From what you have posted to date, using substitution to draw a conclusion the flywheel is the problem.

Magnets loose power over time, loose power with exposure to heat , loose power with exposure to mechanical actions like hammering or with mower engine rubbing on the coil legs .
Coils get hot during use , heat increases the resistance of the coil and if the magnet is marginal to start with then after a few revolutions it could end up being outside the operating range .

That sounds interesting, I will try to find my old compass and give it a try. Sounds like a good way to measure comparative magnetic strength.

 

[bertsmobile1]

That sounds interesting, I will try to find my old compass and give it a try. Sounds like a good way to measure comparative magnetic strength.

Not as good as it sounds but I did find what I thought was a faulty old B & S engine only to find out much latter the magnets were supposed to be reversed so to get the module to work, you need to put it on upside down.
Depends upon the compass but it does sort of work a bit better than the "pulls a screwdriver from 1" away method .

 

[Joed756]

And are you sure the blower housing with the model number on it belongs to the engine it is on.
More than once I have been caught out because the covers had been swapped and what was under the hood was not the original engine.

I'm very impressed you figured that problem out, I don't think I ever would have found it.

 

[bertsmobile1]

I have just fitted a 406722 into a z435 that originally had a 44L777.
The owner wanted to retain the original blower housing so he could continue to buy the JD engine maintenace kits
So the bower says 23Hp JD but the engine is a 19Hp.
Very common for a customer to come in with a second hand mower and the blower housing is from a much bigger mower.
Funny you almost never see them the other way round .
A little more suspicious is when the Hp decal on the housing seems newer than the rest of the mower
Turn over an extra $ 200 for the cost of a $10 decal .

 

[moodymac]

No, the cover is original. The gentleman that owns it owns seven self-propelled push mowers. He is a little eccentric, I have been servicing and maintaining them for years. I believe the problem is in the flywheel magnet. I have a source for a used flywheel, however the shop that it is at is closed due to COVID. It will be several days to wait to try it out. I will report back here with the results, thank you for helping.

 

[StarTech]

What Briggs might have done was to change the fan and shroud on the later engine as the IPLs shows the same PNs. It would not be the first time Briggs did this.