Mower coil resistance value

[ipbr21054]

Morning.
Been given a petrol mower name on label is Wilko.
On the top enging cover it shows DG350 98.5cc & has an OHV engine.

I could smell something like meths / parafin so i emptied the tank / cleaned it & put in fresh fuel but still the mower would not start.
I removed the fuel pipe at the carb & petrol came out so all ok there.

So i removed the carb & give it a clean.
The brass jet which has 3 holes in it has been cleaned but the holes do not line up so you cant see through them etc for a blockage but i think they are now all clean / free.

I am able to blow into the carb inlet fuel pipe fine & when i lift the float up i am then unable to blow again untill i lower the float so to me this all seems ok.

I have removed the spark plug & tried 2 others that i have but still the mower will not start.

Ive have now removed the coil & checked it with a multi meter.
With the meter set at 20K i put the RED lead in the spark plug cap & the black lead on the coil metal piece, My reading on the meter is 11.87

Does this tell you that its working but resistance is to high & that is my problem as to why the mower will not start.

I am able to pull the cord to start it but it just pulls the engine over but no attempt to fire / start not even a pop or backfire etc.

Please advise Thanks

 

[Burnerman]

The best idea is to check for a spark by using a good known plug earthed out onto the mower engine.....you may have to look for a spark in the dark though!
Remove any cut out wires from the coil as you do so.
John

 

[ipbr21054]

Using a plug in the lead to the engine i see no spark when cord is pulled.

 

[Burnerman]

Ok, then remove any cut out wires as I said above, just to rule any switches out.
The gap between coil and flywheel should be the same as a couple of sheets of paper, i.e minimal but the two mustn't touch.
If no joy after that then it sounds like the igniter. I can't give you any resistance readings until tomorrow regarding that one.
John

 

[ipbr21054]

There is only 1 wire of which ive removed.
Ive also checked this wire & it works correctly as when the brake bar is operated it presses down the switch which make the connection for continuity or not.
I will reset gap now

 

[Burnerman]

If you don't get anywhere, try matching the coil from the GHS website......maybe under Mountfield or Briggs to kick off.
John

 

[ipbr21054]

Well i couldnt start this mower or see a spark so i ordered a good used working condition item from Ebay.
Just fitted it but still no joy in respect of the mower not starting.


There is a small low tension wire which connects to a switch below the arm that touches the flywheel / connected to brake arm.
I operate the brake arm & see this switch "brass bullet item" pop up & down,also checking it with a multimeter it also shows its working.
Ive tried starting mower with & without it connected but nothing.

I have swapped the plug for another that i have but still the same.
Even though i dont see a spark im looking at the fuel side of things.

I dont think its my imagination but i dont really smell fuel as if its flooded etc.
Plug isnt really wet at all ?

Ive removed the pipe from tank to carb & my fresh fuel purs out.
With the carb removed from engine but still connected when i press the red primer item should fuel then squirt out ?
On the back of the carb is a small hole when the carb is tilted slightly & i press the red primer i see fuel squirt out.
If i angle carb as if on the mower & do the same again i dont see any fuel.

I here a hissing noise like air but no noise like fluid if you know what i mean.
I put my finger over the small hole & press the red primer where i can feel resistance so red primer seems to be fine without holes / split etc,removing my finger from the hole ythen releases thepressure.

I cleaned the carb & cleaned the brass main jet if thats what its called

I AM NOW NOT SURE WHAT ELSE THERE IS TO DO

Attached are some photos

 

[Burnerman]

You must look for a spark.....if necessary check in the total darkness with a crocodile clip and wire between the plug and the engine casing.
Regarding the primer button, that just delivers a puff of air into the float chamber of the carb.....that in turn shoots a bit of petrol up through the main jet for a cold start.
John

 

[ipbr21054]

OK
Will check spark tonight.

Ive just taken off carb & clean it out again.

 

[Burnerman]

You can always tip a little fuel down the plug hole and see if the engine fires once or twice......its not foolproof but sometimes the sparks are very difficult to see in daylight.
These igniters produce very high voltage with a very low current - hence a tiny spark. The 'big fat spark' of the old days have gone - which is one of the reasons spark plugs last so long!
John

 

[ipbr21054]

Can you check the coil resistance value please.
Attached are the values from my coil & the purchased coil off Ebay

 

[Burnerman]

I'm getting anywhere between 4k and 200k on the coils I have so I reckon your reading is ok.
Do the in the dark spark test next!
John

 

[ipbr21054]

Will check for spark later.
There must be a range specific for each mower as the higher the ohms value the less spark will be produced

 

[Burnerman]

Indeed the coils are specific and the resistance ranges vary enormously but I’ve no idea what your specifications are.
However, as a general rule you should see 20k or less connecting between the kill wire terminal and the coil metal frame, and 30k or less between HT cap and kill wire....primary and secondary windings.
John

 

[ipbr21054]

Ive bought a can of carb cleaner & squirted it into the carb port with air filter off,started fisrt pull.

So as i have fuel running from the pipe to carb the issue is inside the carb ?

Ive taken it apart twice and cleaned anything that can be removed so wondering why fuel is being starved from the engine.
I think were getting somewhere now