Coil troubleshooting

[oneliterbeater]

I love and appreciate all the knowledge here in the GS forums, but I still haven't figured out how to search worth a dang. So...does anyone have an idea on where to look for troubleshooting a coil on the new to me 450L I just picked up? I have a dead cylinder with no spark. Tried a new plug and same result. Tested by grounding to engine. That being said, I really don't know how to test the coil itself. I have a meter and know how to use it, but not sure what measurements I should have and where.

Ant help is greatly appreciated.

[hikermikem]

With the power off, the primary sides of each coil (where the leads go) should read 5 ohms (assuming stock coils) - the secondary sides (where the plugs go) should read approx. 35K ohms.

If the primary sides are shot, then the coil is toast, if the secondary sides get no reading, then try unscrewing the plug cap, snipping off about a 1/4" of wire to get to clean stuff, screw the caps back on & try again.

Often times the plug cap connections get old & corroded.

[1_v8_merc]

Yep, bad plug wires or caps are often mis-diagnosed as a bad coil...simply because someone can't get a reading from the coils!
Speaking from personal experience too.

[hikermikem]

Yep, bad plug wires or caps are often mis-diagnosed as a bad coil...simply because someone can't get a reading from the coils!
Speaking from personal experience too.

I've had that "experience" as well...

A good upgrade is to ditch the OEM caps & replace with new aftermarket NGK ones. I believe Cliff's site has some info about that, showing the different cap styles & sizes.