No spark on my 1979 Mariner 3.5 air cooled

[bikerbill]

Hi all

My old Mariner 3.5 would start but not run, so I stripped and cleaned the carb and replaced and gapped the points today, now it won't start at all as there is no spark at the plug.

How can I check if there is a spark at the points and how can I check if the stator coil and condensor are ok?

Thanks in advance

Billy

 

[mtb]

you could

Be sure you've not earthed the points ! be sure their opening and are also opening enough oh and closing ;-)
Try cleaning the points surfaces with thinners and or a dry clean piece of paper, put the paper in then close the points draw the paper out. You'd be surprised how much dirt or grease you'll get even on new points
Check condensor and low tension wire re to points and to kill button
If you can why not spin it over in the dark its the best way to see the spark or if the ht lead is breaking down
of course you could use the plug earth it to the engine and spin it over to see if theres a spark or if its weak
years ago I had a bit of kit that fed power in through the circuit and showed the quality of spark It loaded up the coil so you could check if it was breaking down.
a little firm from white Waltham made them, but not much need for gear like that after the late 1970s

cheers
mick

 

[bikerbill]

Thanks Mick

I'm not sure what you mean by the 'points being earthed', don't think they are though. Both the condensor and stator coil wires are connected to the points and they are opening and closing I have found out how to check the condensor, which I will be doing later, then check for a spark in the darkness as you suggest.

Thanks again

Billy

 

[VicS]

If it previously started and now there is no spark look again at the fitting and gapping of the points.

Be sure you've not earthed the points !

Yes make sure the moving point is not shorting to earth. Sometimes it's quite easy to miss-install a spacer or insulator.

be sure their opening and are also opening enough oh and closing ;-)

The gap should be set to the specified value when the points are at their widest open.

Try cleaning the points surfaces with thinners and or a dry clean piece of paper, put the paper in then close the points draw the paper out. You'd be surprised how much dirt or grease you'll get even on new points

They should be scrupulously clean. Not so much as a finger print!

All you can do with the coil without testing equipment is to:
inspect it.... it it looks manky or the insulation is damaged replace it

Check the primary and secondary for continuity.

About all you can do with the condenser is to replace it if suspect

 

[rosssavage]

Clean the points... New ones are often coated in thin oil to keep the surface clean during storage.

Had the same problem on a Volvo AQ150 - drove me nuts until I cleaned the brand new points!!

 

[bikerbill]

Thanks all

I have double checked the stator & condensor which are giving me readings! Now it looks like the HT ingition coil might be suspect, because I can't get a reading when I connect the meter to the spark plug end of the HT lead and the black wire from the coil.

 

[VicS]

Thanks all

I have double checked the stator & condensor which are giving me readings! Now it looks like the HT ingition coil might be suspect, because I can't get a reading when I connect the meter to the spark plug end of the HT lead and the black wire from the coil.

Maybe just the HT lead ?

Check the stop button.