V7 no spark, both secondary coils no resistance value

[09dudharb]

Hi,

Moto Guzzi V7 stone 2013.

New to the site, thanks for having me. I had a V7 for 3 years a while back and it never missed a beat but bought one at the weekend and its now not starting.

*Background*
The bike started okay on collection but after getting home (2hr ride) and a hour or two gone cold, the bike took about 5 seconds to crank and start. This was the case for the next 3 times it was started, one of which started and then died after a few seconds. Went out to the bike yesterday and wouldn't start at all.

*Checks so far*
Pulled plugs and grounded to the cylinder, no spark. The ends of the both spark plugs were blackened (HT lead end) - pictured below. Unsure if this means it was arcing. Checked the HT leads and they were rather messy. Coil pack end of one HT lead was caved in and only half inserted to the jacket. The other lead fell out of the elbow spark plug end. Sorted this and managed to get resistance over the HT lead but still no spark when reconnected.

I then moved onto the coils. Touching probes onto each of the two coil pack pins gave me a reading of 14 (sorry not sure what multiple I had my multimeter set too). I then probed the HT lead connection point on the coil pack and on the electrical pins. I tried this with positive on HT end, negative on pins and visa versa. I tried on all resistance settings on the multimeter, tried on either electrical pins - all resulted in no resistance. This was the case for BOTH coil packs. Similar readings on the primary, no reading on the secondary.

Can someone confirm if I have messed up reading the secondary coils? If not, does anyone have a clue how both could go pop overnight? I know the HT leads wern't great but it seems odd that both coils went at the same time.

The bikes got a replacement reg/rect by the looks of it, there's no part number but the brand is 'LP2'. The wiring is a bit messy as it has aftermarket indicators, heated grips and a usb charger. Lots of plugs kicking about unconnected. I've attached pics of the two that were accessible. The one by the headlight I believe goes to the little bulb at the bottom of the head light. The connector by the airbox I've got no clue, can't find it anywhere on a wiring diagram I've found online. Any help with this would be appreciated also! Unsure if this is related but thought I'd mention it just in case!

[Tom H]

Give this a shot. Insert your coil end of your plug wire into the coil. Take your meter and neg lead to a good ground and the pos lead into the spark plug end of the cable. You should see about 8 (8K?) ohms resistance. If so, the coils should be good.

Good luck,
Tom

[09dudharb]

Give this a shot. Insert your coil end of your plug wire into the coil. Take your meter and neg lead to a good ground and the pos lead into the spark plug end of the cable. You should see about 8 (8K?) ohms resistance. If so, the coils should be good.

Good luck,
Tom

Cheers Tom, appreciate that, will give it a crack tomorrow. UK based so getting a bit dark now!

[Tom H]

I should have added. The coils if tested without the plug wire inserted S/B about 3 (3K) ohms. The wires from end to end S/B about 5 (5k).

Let us know how you do.

Tom

[09dudharb]

I should have added. The coils if tested without the plug wire inserted S/B about 3 (3K) ohms. The wires from end to end S/B about 5 (5k).

Let us know how you do.

Tom

Just tested, both coils reading infinity :( I think they must both be blown. No idea how that's happened to both at the same time though! any ideas?

[09dudharb]

Just a thought, all the tests I've done have been with the electrics off and the battery disconnected. From my fairly limited leccie knowledge that seemed to be the safe thing to do - am I right in doing this? Surely when I've been testing the secondary coils at the packs themselves I am just checking continuity of the windings therefore need no power. Just trying to cover all bases as it seems unlikely that both blew at the same time.

[Tom H]

That would be odd for both to go.

Are you sure your getting a good ground with your meter? When I have done as I described on my EVT, the battery would be connected and key turned off. Meter lead to plug wire end and the other lead to the rocker cover.

Did you try one lead of the meter on the mounting bolt for the coil and the other into where the plug wire goes in? Sometimes it can be a bit fiddly getting a good connection.

Tom

[moto-uno]

  Do you have 12V to either coil with ignition on ? If so , does it stay at 12V when you wiggle the crap out of the harness ?
  Do you have points ignition ?
  Do you have spare condensers?
  If points , do you have any gap ?
Peter

[Kev m]

 
Do you have 12V to either coil with ignition on ? If so , does it stay at 12V when you wiggle the crap out of the harness ?
  Do you have points ignition ?
  Do you have spare condensers?
  If points , do you have any gap ?
Peter

It's a single throttle body EFI smallblock so no points or condenser.

I would have to read a wiring diagram to see how/when coils are powered. Probably one or more relays control it and ECM provides timed grounds.

I would bet dollars to donuts that it's NOT the coils. Both don't just go bad intermittently and then fail all together at the same time no way.

[guzzisteve]

I was curious last night & looked up on hi def diagram, all coil wires go to ECU, no relay involved. Check all safety switches. They tell ECU it's OK for coils.

[73 sport]

   If the plug wires are carbon core, there may be internal disintegration which then could pass low voltage test current but not the coil voltage.

[Kev m]

I was curious last night & looked up on hi def diagram, all coil wires go to ECU, no relay involved. Check all safety switches. They tell ECU it's OK for coils.