HELP! Voltage at Coils

[Bondyboy96]

Hi guys, getting fed up of still getting no spark on my fazer cafe racer build. Been through all the micro switches (sidestand etc) tested the coils, leads, plugs etc. Even tried another wiring loom, but still nothing. The new loom fixed the problem of a badly installed alarm and nothing happening when the starter was pressed. I am now thinking its the CDI box itself, i tested the voltage reaching the coils and without turning over its about 12.8 volts, but when the button is pressed it drops to about 7v? should this be happening? If anyone has any other ideas please speak out! haha


Cheers guys
Max

[Paulfzs]

scrap last post.


if its dropping the cdi will be knackerd


capacitor discharge ignition is used to raise the voltage to 250-600v then when its told to spark itll dump it causing the spark so try a new cdi.

[Bondyboy96]

Ok, will try in the morning thanks!

[Fazerider]

The Fazer doesn't have a CDI unit, just a standard transistorised ignition, this will give a low-ish voltage reading on a meter. In addition, the battery volts will take a fair hit while the starter is churning the motor over.
Not saying the ignitor box isn't the problem, just not to expect a reading of hundreds of volts at its output.

[Paulfzs]

have you tried 12v direct to the coils to see if it sparks

[Paulfzs]

The Fazer doesn't have a CDI unit, just a standard transistorised ignition, this will give a low-ish voltage reading on a meter. In addition, the battery volts will take a fair hit while the starter is churning the motor over.
Not saying the ignitor box isn't the problem, just not to expect a reading of hundreds of volts at its output.

^^
ignore my above post then, didnt know fazer doesn't have cdi.

[Bondyboy96]

Ohh i see, thought it was CDI. In that case does much change?

[Fazerider]

Not really, mostly that was me being a pedantic git.


Changing the box is still probably a good bet assuming you tested the pickup coil as well.
Swapping all the major components one by one is usually the quickest solution unless you have more advanced measuring equipment, like an oscilloscope, to hand.

[Bondyboy96]

ohh ok, haha just tested the rear lights and upon pressing the starter the voltage drops to under 7v aswell, so guessing there's a short somewhere causing a big voltage draw, explains the dead battery!

[Fazerider]

Does the engine actually turn over when you thumb the starter?

[His Dudeness]

Have you tried using another battery or jumping it off a good battery? Even a car battery would do. Batteries can show a good voltage with no load but collapse when there's a big current draw. Try measuring the battery voltage when you're turning the engine over if it drops to 7v at the battery again then the battery would need to be replaced. Cold weather seems to finish off weak batteries too.

[unfazed]

Have you tested the pickup coil?

[Ebme Geek]

I am going with your battery droping too much for the ignition to fire, but must ask how fast does it turn over ?
 
On a side line,
do hear the fuel pump tick a few times when you turn the ignition on ?
Just a silly one, you are holding the plug against the cylinder head, not the cam cover, it's rubber isolated.
 
Loose thoughts, if had been checking for sparks against the cover and this has been a red herring,
might be there is no fuel, as i say loose thoughts ....

[Bondyboy96]

Hi, yeah replaced the battery yesterday. Old one was down a cell, we now have a spark! And yeah was testing against cylinders, however I have a spark plug tester now, makes like easier! Thanks guys