Qualcast Suffolk Punch 35s Problem

[manuel]

I turned the motor over with a portable drill while the spark plug is removed from the engine but with the thread of the plug connected to the frame and the HT lead connected

would not turn it over while the plug is in as it would damage the drill had it started but have tried to start with the pull cord (correct way) I think I would have seen it spark

regardless of any damage to the valves ?

[GardenKit]

Fair enough.

 

Are the flywheel magnets strong?

[manuel]

from my point of view just cant see the magnets just dying only if they were electrical operated I checked the magnets they seem to be ok also checked if there was play in the shaft as the distance between the module and the magnet can influence the voltage induced in the module that seems ok

 

I assume that a spark can be seen when removed from the engine and I know there is a voltage there as I felt across my fingers but not powerful to create a spark ?

 

and with a volt meter there is some movement

 

but the normal analogue volt meter my not give a true reading

[GardenKit]

I have known flywheels to have weak magnets, and they all started and ran until they did not. I dont think its a case of suddenly dying, but rather that they have just reached too low a level. They should hold a small 4" flat blade screwdriver.

 

Another thought. Are you using a resistor plug? If so try a non resistor, they will spark at a lower voltage.

[WeFixIt]

Interesting puzzle ?

 

A few questions if I may!

 

What make and type plug have you got?

 

What distance do you have between the flywheel magnet and the HT coil?

 

When you say you have the plug clamped when testing with a battery drill where have you got it clamped?

 

Does this mower have electric start and a battery fitted?

 

 

 

 

Is it a chipper, is it a mower or another broken stump grinder who cares we'll fix it!

[manuel]

I'll try to answer both questions but first just like to say thanks for all your responses

 

My first post I said I connected the plug directly to the HT lead bypassing the suppressor cap with no luck the Plug was champion RJ19LM, tested the centre electrode and found it to be open circuit replaced it with J19LM from the local Halfords it was the only place around that had a plug to fit Tested the centre electrode on the new plug that as a very low resistance reading totally continuity

 

and when testing the plug out off the engine I clamped a copper strap to the thread of plug and connected the other side to the frame on the engine with a gap of 25 thou my gauges or imperial have tried 20 but still no luck

 

The only electrical parts on the mower are module HT lead, kill lead which is disconnect, the spark cap which as a resistance of 10K which is the suppressor, the spark plug and the magnets

 

 

 

There is no electric starter on this mower wish there was it's a pull start on the side

 

the gap between the magnet is total fixed as the magnets are imbedded in the inside of flywheel so with the flywheel in place its impossible to check the gap and the module as no adjustment total locked down with two screws the magnets due hold a screw driver with no problem

[hedgesparrow]

there shoud be adjustments between flywheel and coil if its to big will not get a spark the coil should be slotted so you can adjust it. as gardenkit try a screwdriver on flywheel magnets see if it will stick a screwdriver to it.

you can get a spark plug tester looks like a spark plug wich when you pull the engine over flashes to say if you have a spark.good bit of kit to have.

you say it went bang and backfired. as other post take flywheel off and check key more than likely it has sheared so not keeping flywheel in place correctly. they are only ali so do shear. only pence from a mower shop.

be interested to see.what the problem is i reckon the key has sheared.

[mikerecike]

 

Another thought. Are you using a resistor plug? If so try a non resistor, they will spark at a lower voltage.

 

Never knew that! Nice one Barrie.

[mikerecike]

Hows the connection under/between the plug cap and the HT lead? Dealt with several where the pin has pulled partially out of the lead weakening or making the spark erratic. This wouldnt have caused a backfire but could explain the weak spark.Personally I stick to NGK.

[manuel]

Hi People

 

I have checked the key on the shaft when I first replaced the Electronic module and I can assure everyone that the shaft key and the flywheel are keyed ok that is what I checked first, the module can not be moved it a wimpac 3 pole module that can only be fix to stationary part around the shaft of the engine so the magnets moving around create the magnetic field

If there was a means of movement it would be total guess work as the magnet may foul the module, when the flywheel is placed over the shaft you can not see the position

 

looking a the problem

 

was the backfire caused by the engine firing at the wrong time or was there fuel in the exhaust manifold that ignited

but why no spark am assuming that a spark can be seen when testing out of the engine

 

it is such a simple setup I tested the kill lead and the continuity of the HT lead all the way to the centre electrode of the spark plug

 

is the spark plug that I have replaced a compatibly replacement

 

but holding the HT lead close to the frame with a small screw in the lead still no spark