manuel

Update Success it working replaced the head gasket spoke to a guy who repairs Suffolk lawn mowers he says the on a electronic ignition if very unlikely to see a spark until it's turning over at the normal idling speed tested with the old electronic module in and it did not start therefore the electronic ignition needed replacing and the spark plug failed and the head gasket needed replacing Thanks to all that kindly posted with constructed advice Time to cut the lawns ?

Hi Cornish wood burner the part is a genuine part F016L34244 while turning it over with my arm I notice that fumes were going out of the side of the engine and assume the back fire had blown a small amount of cylinder gasket out so have taken the head off the engine and waiting for a new gasket to arrive will update ASAP

both wefixit and Cornish wood burner are right in there post but when the flywheel is on it total covers the module and in not accessible at all the module contains the iron core coil and the electronics is encapsulated in black resin with a steel bracket with screw holes in which can not be adjusted and the magnets are embedded in the inside of the flywheel I have replaced the module twice which automatically replaces the kill wire and HT lead have replaced the spark plug at this very moment are disassembling the mower for the 5 time it seem a simply problem for me as a Electrical Engineer will check it again

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

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

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

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 ?

aluminium flywheel with imbedded magnets it the one that needs the 3 pole electronic ignition module

I am not sure but it maybe a Briggs and Stratton Electronic ignition model 98cc

The module is encapsulated with only two wires coming out of the module the trip wire and the HT wire I have also tried a second module here is no coil that came be seen only the three metal parts coming out of the module there are there to pick up the magnetic field when the magnet in the fly wheel passes the module and with a bit of electronics inside and a transformer increase the voltage when the magnetic field collapses and in the last few days have tried a second module and did try with the trip wire disconnected because that seem to be a common problem that is over looked But sorry to say no spark

My first post. Hope this is the correct section to post this question I have a Qualcast Suffolk Punch 35s electronic ignition lawn mower that as be cutting my lawns for a long time with no problems, just a service at regular intervals. But the other day while trying to start the lawnmower there was a bang which I believe to have been a back fire? After then the mower would not start I checked the fuel and the carburettor that was ok and the compression But unable to produce a spark at the spark plug Being a electrical engineer I checked the cut off lead and the continuity of the ht lead all ok Replaced the spark plug with a new one as there was no continuity on the centre electrode Also replaced the electronic module 3 pole unit inside the flywheel with a new one Which as all new HT and trip wires cables attached And still no spark also removed the spark plug cap which from the reading as a 10k ohm suppressor built-in and connected the lead directly to the plug Inside the flywheel the electronic module is screwed in place with no adjustment and the flywheel with the magnets build in are keyed to the shaft so there is no adjustment There is a small voltage at the plug but nowhere a voltage to create a spark also turned the motor over with a portable drill with the spark plug removed and the thread connected to the frame Has anyone any suggestions what maybe wrong with the mower that’s stopping it sparking at the plug