starting problem on countax ride on lawnmower

[johntheo]

Its a strange one alright, presume nothing daft like a 6V starter or reversed battery polarity, can you try a different battery.
If its the normal pre engaged type starter then you might have one wire going from start button to the solenoid, there will be a much heavier cable direct from the battery to the main starter terminal, when the start button is pressed the solenoid is energised and engages the pinion with the ring gear and also closes a contactor to stat turning the starter to start the engine. You could check the resistance between the solenoid coil + and the body of the starter and see if you have continuity or a fairly low resistance as I think that the solenoid coil is also connected internally on the negative side to slowly turn the pinion while also engaging it before the main contacts close.

 

[johntheo]

Looking at a schematic it just looks like a inertia type starter motor so no pre engaging.

 

[stephen181]

Its a strange one alright, presume nothing daft like a 6V starter or reversed battery polarity, can you try a different battery.
If its the normal pre engaged type starter then you might have one wire going from start button to the solenoid, there will be a much heavier cable direct from the battery to the main starter terminal, when the start button is pressed the solenoid is energised and engages the pinion with the ring gear and also closes a contactor to stat turning the starter to start the engine. You could check the resistance between the solenoid coil + and the body of the starter and see if you have continuity or a fairly low resistance as I think that the solenoid coil is also connected internally on the negative side to slowly turn the pinion while also engaging it before the main contacts close.

hi, tried a different battery, the starter is not pre engaged, it throws th cog into the flywheel at least it used to! the solenoid is a seperate unit when the ignition is turned on a voltage goes to it, the other half of the coil is grounded. you can hear the contactor working and a multimeter shows that it puts the voltage to the starter motor.
it is strange, i am fairly convinced that both starter motors have failed - but why is the puzzle?
cutting an acre of grass with a push mower is not great!

 

[johntheo]

If its throwing a cog onto the flywheel then the starter motor must be turning fast enough initially at any rate to make the pinion move along the shaft?. What is the resistance across the terminals? I suppose it should read nearly zero ohms, if burned out then probably infinity.

 

[stephen181]

Looking at a schematic it just looks like a inertia type starter motor so no pre engaging.

that is correct, i posted a breakdown of the starter earlier - there is nothing to it -static magnets, an armature which tested fine and 4 brushes which were in good condition and all the springs were intact

 

[kilotango]

hi, tried a different battery, the starter is not pre engaged, it throws th cog into the flywheel at least it used to! the solenoid is a seperate unit when the ignition is turned on a voltage goes to it, the other half of the coil is grounded. you can hear the contactor working and a multimeter shows that it puts the voltage to the starter motor.
it is strange, i am fairly convinced that both starter motors have failed - but why is the puzzle?
cutting an acre of grass with a push mower is not great!

Hi Stephen, have you solved the starter engagement?
I Have exactly same issue and a similar field to mow...
Contactor clicks, starter fly's up but engine turns to slow to start. Battery vitals are fine.
Starter, checks out ok, & it fly's to engage.
I am going to try with the plug out to see if engine turns over faster with less resistance.
Next, I will change dc contactor to eliminate this as an issue.
Please let me know if you got to bottom of problem?
J

 

[stephen181]

Hi Stephen, have you solved the starter engagement?
I Have exactly same issue and a similar field to mow...
Contactor clicks, starter fly's up but engine turns to slow to start. Battery vitals are fine.
Starter, checks out ok, & it fl

 

[stephen181]

it turned out new starter was duff. if petrol is getting into chamber (dirt in carb) then it will create high resistance.
use car jump leads to bypass other leads. one from battery to starter body, one from live battery and just touch the live input on starter. this will show if any permanent leads are duff i suspect solenoid is ok
s