# [SOLVED] briggs and stratton 5HP sparking issue



## ellies grandad

I have an old B&S 5HP engine running my old Norlett 5000 rotovator. Having a starting issues. I have cleaned condenser, points, and coil and fitted new plug but for some reason I have a great spark when connecting the plug tester to the plug lead and grounding it (it flashes like a Christmas tree) but when connected in between plug and plug lead, nothing so I can only assume its grounding elsewhere. I have removed the kill switch wire but still wont work so naturally it isn't that. Any ideas please?


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## AVB

*Re: briggs and stratton 5HP sparking issue*

The new plug could be bad. Try a known good plug.

One additional test you can perform. Check the impedance (resistance) of the secondary circuit at room temperature. Hook an ohmmeter test lead to the spark plug terminal of the high-tension lead and another to the lamination stack (ground). Your resistance reading should range between 2,500 and 5,000 ohms. If infinite (no continuity), an internal open circuit exists. Replace the coil. If infinite and the engine runs, your problem is an internal break of the high tension lead, a poor attachment of the spark plug terminal or improper mating of the high tension lead to the coil. A pin within the coil body skewers the lead. If the pin does not contact the wire core, there will be no continuity. The coil will often have enough available voltage to jump the gap, so you see spark. The internal arcing that occurs within the high-tension lead will eventually create enough resistance that ignition system performance will suffer. If your resistance reading is much lower than 2,500 ohms, an internal short exists. Replace the coil.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

Hi, thanks for your reply. I have tried 2 different plugs with the same result. whilst there, I did do a further test on the condenser as described on the internet and the condenser failed so I have ordered another one anyway. I will also try your test and report back asap.


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## AVB

*Re: briggs and stratton 5HP sparking issue*

That is actually an extract from a Briggs article on ignition testing.

If you don't mind I would suggest checking the valve clearances while your working on this engine as the L-head gaps tends to close up over leading to valves not fully seating causing starting problems too.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

Hi
I have tested the coil. setting the multimeter at 20k on the ohms field, I had a reading of 2.74 so all seems ok on that front and also there was good contact on the HT lead pin.

I cant help thinking, could it be the condenser. The machine was it a shed which was severely damaged in last years gales and it did get a bit wet. When I took the points and condenser cover off. It was damp inside but wasn't rebuilt until completely dried out. I have cleaned and rebuilt carb with new jets gaskets, and diaphrams and have got good fuel flow. I have another coil but unfortunately that one has not got the wire on it which runs to the condenser so cant try I don't think.


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## AVB

*Re: briggs and stratton 5HP sparking issue*



ellies grandad said:


> I cant help thinking, could it be the condenser. The machine was it a shed which was severely damaged in last years gales and it did get a bit wet. When I took the points and condenser cover off. It was damp inside but wasn't rebuilt until completely dried out. I have cleaned and rebuilt carb with new jets gaskets, and diaphrams and have got good fuel flow.


Could be as it would boost the current flow for coil making the spark last longer inder load.


ellies grandad said:


> I have another coil but unfortunately that one has not got the wire on it which runs to the condenser so cant try I don't think.


It depends if your engine is aluminum or cast iron. The aluminum engine can be easily converted to the magnetron ignition system as long as the magnetron coil is from another Briggs 5 HP donor. The 3-4 hp and 7-16 hp coils won't fit.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

Its an aluminium engine so if all fails once I have fitted the new condensor, how do you convert it please as ive never attempted that before. I can easily get a donor magnetron coil as the spares I have at present have all come off of 35 and 4.5 series mowers


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## AVB

*Re: briggs and stratton 5HP sparking issue*

I am not familiar that with those 35 and 4.5 series mowers I usually reference the engine model numbers themselves. Stilling learning a lot about how others reference equipment. 

If the engines are 5 hp versions then the coil would simply just bolts on as the old one does except you don't connect the lead that currently goes to the points. The terminal on the magnetrons is the kill terminal for shutting down the ignition when you stop the engine. Depending on how that particular engine was wired you may need to move that kill wire to the coil terminal as I have seen a few with it running to the points but where already at the coil terminal. The air gap between the coil legs and the flywheel is .010"-.012".

Briggs did provide a plug to replace the points plunger but you can simply let point system stay as is; just not electrically connected.

Back in the '70s when I was in high school (I know telling off my age) Briggs was selling a conversion kit for failing points that consisted of a slip-on magnetron trigger which is now built into the current coils. I haven't seen one in years.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

Im beginning to see how it all may add up now because the set up in my machine is one wire running from the coil to the condensor, and another running from the same port hole in the condensor to the kill switch which on operation from the handle simply grounds the extra voltage, so the condensor may be the issue. As soon as it arrives I will fit a let you know


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## SABL

*Re: briggs and stratton 5HP sparking issue*

If it didn't need a condenser they sure wouldn't waste money installing one. I had a '71 VW Beetle that liked to eat condensers. That was long ago.


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## AVB

*Re: briggs and stratton 5HP sparking issue*



ellies grandad said:


> Im beginning to see how it all may add up now because the set up in my machine is one wire running from the coil to the condensor, and another running from the same port hole in the condensor to the kill switch which on operation from the handle simply grounds the extra voltage, so the condensor may be the issue. As soon as it arrives I will fit a let you know


That extra wire on the condenser is the one I that mentioned previously may need moving to the magnetron coil kill terminal and the other one disconnected or could simply connect them together and tape them; just don't put them back in the condenser if you which over to magnetron coil. But being me I like to keep it neat with less chances of shorts.



SABL said:


> If it didn't need a condenser they sure wouldn't waste money installing one. I had a '71 VW Beetle that liked to eat condensers. That was long ago.


The condenser was used to help prevent the point contacts from burning and pitting as they open. It is nothing but a capacitor that supplies the current and voltage for short time longer as the points contacts opens helping to prevent that familiar arcing as the contacts open.

These is old style ignition systems where replace by the new electronic triggered systems. Several vehicles that I repaired in the late 70's and 80's even had conversion kits to do away with points and condensers.

In the case of the magneto system they just switch to letting the flywheel magnets trigger an electronic version of the points system. This was nothing but a trigger coil and transistorize switch. They have now advance to point that they no longer using this system in flavor of the ignitor triggered system.

Here is a couple diagrams to help explain. The first is how the first generation trigger was setup and second is an example of wiring in the latest ignitors. The latest ignitors can even used with the old cast iron small engine that had reversed polarity magnets.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

thats great thanks. If the condenser theory doesnt work, I have found a new coil online which according to B&S is the replacement coil so as to do away with the points and condenser as it is wired to give a stronger spark...nicely priced too.


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## Basementgeek

*Re: briggs and stratton 5HP sparking issue*

FYI ellies grandad

You would be surprised how different a plug fires in free air than under compression. The higher the pressure the less spark.

BG


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

I did hear that from a company called Briggs Bits, They also said that their newer coils were introduced to create a stronger spark and eleviate the need to remove the flywheel assembly to access the points and condensor. Who knows we may even see an "ECU" in a mower yet.


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## AVB

*Re: briggs and stratton 5HP sparking issue*

I would say we are very close already with fuel injector systems out there now and with Kohler improving on their DSAM Ignition System on the twins. Their DSAI had problems due the need of 12V so they have replaced it with MDI modules which are magnetic driven.

And there are the Stihl M-tronics and Husqvanra Auto tune carburetors on the chainsaws that are software driven. Just to work on the Husqvarna Auto tune you need the diagnostic software and a cable that plugs into the chainsaws.


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## wristpin

*Re: briggs and stratton 5HP sparking issue*

Various answers given to this question have quoted impedance figures to expect from suspect coils but while these may be valid from personal experimentation, to the best of my knowledge have never been quoted by Briggs themselves nor contained in their official workshop manuals. Take for example the 270962 Single cylinder L head manual. 
Briggs have never recommended the use of any specialist test equipment other than their various generations of spark gap testers. In fact in days gone by the sole test recommended was "would the spark jump a 1/4 to 5/16 inch gap between the bare end of the plug (high tension) lead and an unpainted surface on the cylinder head. If it did, the ignition system was said to be in good order, if not, there was a fault - as simple as that. 
I would also point out that condenser (capacitor) testing with a multimeter is unreliable and can even result in a trashed meter! The only reliable test is with a specific tester that indicates the capacitor's ability to accept a charge, hold it and then release it.
Finally, as good as the magnetron system is, it does need the engine to be rotated at over 350rpm to give a reliable spark ; unlike the points system which when in good order could produce a spark just by flicking the flywheel .


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## AVB

*Re: briggs and stratton 5HP sparking issue*



wristpin said:


> Various answers given to this question have quoted impedance figures to expect from suspect coils but while these may be valid from personal experimentation, to the best of my knowledge have never been quoted by Briggs themselves nor contained in their official workshop manuals.


Wristpin, I would differ on that as Briggs do; although, it is not the repair manuals. Here is the link to the actual document that I referred to.
Ignition System Theory and Testing


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## AVB

*Re: briggs and stratton 5HP sparking issue*

I would also add the quoted minimum rpm for the magnetron is 250 and not 350.


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## wristpin

*Re: briggs and stratton 5HP sparking issue*



AVB said:


> I would also add the quoted minimum rpm for the magnetron is 250 and not 350.


Page 2 of the ignition section of the Single Cylinder L head Manual -*NOTE :*_Flywheel must rotate at 350rpm minimum on engines equipped with Magnetron ignition! 
_
As far as impedance readings etc go; in over 30years of attending BS Service Update Courses, specific application courses and the four day MST course the message has always been "don't bother with fancy meter readings etc " just do the basic tests using the air gap tester.


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## AVB

*Re: briggs and stratton 5HP sparking issue*

I can agree that it can be a misprint in either place then I would use the higher valve in this case. I have found incorrect info the service and parts manuals before. That is why I download the parts IPLs and make my own notes on them. 



> As far as impedance readings etc go; in over 30years of attending BS Service Update Courses, specific application courses and the four day MST course the message has always been "don't bother with fancy meter readings etc " just do the basic tests using the air gap tester.


When press for time in the shop setting most do probably recommend the "quick and dirty" method. It is all about getting the equipment operational as quickly as possible especially during the busy season. I don't even fool with points most times as I just convert them over to an ignitor system which usually have a better starting performance away.

I do think that most DIYs don't have the Briggs air gap testers and even some shops don't; mine being one.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

with all the above said I have today fitted the new condenser and points kit and hoorah problem solved. I then stuck a piece of reflective white paper on the flywheel nut and have adjusted the revs with a digital rev reader. and she's ready for the allotment as soon as it stops raining. All I have to do now is persuade my son to use it LOL.


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## SABL

*Re: briggs and stratton 5HP sparking issue*



ellies grandad said:


> All I have to do now is persuade my son to use it LOL.


Good luck....I have the same problem. But....it'll be months before mowing season rolls around. The snow hasn't melted yet......:frown:

Glad to hear you got the problem sorted out......:thumb:. I haven't dealt with points/condenser for a long, long time. 

I can mark this thread SOLVED if you wish.....or you can click THREAD TOOLS and get some practice......:grin:


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## AVB

*Re: briggs and stratton 5HP sparking issue*



ellies grandad said:


> with all the above said I have today fitted the new condenser and points kit and hoorah problem solved. I then stuck a piece of reflective white paper on the flywheel nut and have adjusted the revs with a digital rev reader. and she's ready for the allotment as soon as it stops raining. All I have to do now is persuade my son to use it LOL.


Glad you got it fixed. It is always nice hear back when things are finally fixed.

As getting the son to used it that might be a more difficult task than the repair work.


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## ellies grandad

*Re: briggs and stratton 5HP sparking issue*

thanks all for your help and advice, I think we can mark this one as solved but watch this space as my next project is a rescued Honda HR194 all singing and dancing petrol mower which my son came across whilst out working but is in a sorry state.


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