PLEASE help with no spark

[Teddo]

As I recall the plugs did seem pretty dry. 
I'm thinking of replacing my fuel filter while I have the tank off (was a struggle getting that vent hose off!) with an all metal one - any suggestions?

[Bulldog9]

Most EFI systems that don't have a redundant way to track engine speed to determine ignition and EFI timing will CUT both ignition and fuel with a CKP sensor failure. It stops triggering the ignition coils and stops fuel injectorv pulsing.

So no wet plugs.

Right, but if the CKP/CPS - ( meaning crank position sensor) is good, the ECU would trigger the fuel and spark, but if the coil is bad no big bang......

[Teddo]

Most EFI systems that don't have a redundant way to track engine speed to determine ignition and EFI timing will CUT both ignition and fuel with a CKP sensor failure. It stops triggering the ignition coils and stops fuel injectorv pulsing.

So no wet plugs.

Still wondering why I don't get current to the coils - I would think that the coils are normally charged ( with key on ) and the ecu , via the CPS, would cut power for the spark, no? I visualize the CPS/ECU doing the job that points did.

[guzzisteve]

All the sensor does is pick up a gap in the teeth on the tone wheel which triggers the ecu to send signal to the coils.
I doubt both coils went bad at same time.

[Teddo]

All the sensor does is pick up a gap in the teeth on the tone wheel which triggers the ecu to send signal to the coils.
I doubt both coils went bad at same time.

Is the signal to cut power to generate the spark? If so wouldn't the coils be energized between signals? 

[Kev m]

Right, but if the CKP/CPS - ( meaning crank position sensor) is good, the ECU would trigger the fuel and spark, but if the coil is bad no big bang......

The ECU triggers the coil BASED on the CKP signal.

The TWO coils likely did not go bad at the same time.

The ECU simply isn't triggering them, because...

Still wondering why I don't get current to the coils - I would think that the coils are normally charged ( with key on ) and the ecu , via the CPS, would cut power for the spark, no? I visualize the CPS/ECU doing the job that points did.

Partially agreed, yes, the trigger signal is ground by the ECU.

No it is not designed to be powered all the time key on/engine off.

See wiring diagram (and/or service manual):

https://www.thisoldtractor.com/mg_manuals/wiring_diagram_v7-iii-e4-stone.pdf


Power supply is 12 V - Red/Brown wire FROM the Injection Load Relay.

Ground is Orange/White (left coil) or Orange/Red (right coil) wire - both go to the ECU

I'm a little confused about what the third wire on the right coil does - "Power Ground 2" according to service manual - Blue wire (also goes to ECU).

Anyway the Red/Brown wire appears to power a bunch of things (both coils, both injectors, fuel pump, and both O2 sensors, presumably the heater circuits). BUT it only does so when the injection load relay is activated, and then it is providing power directly from the regulator/rectifier.

Which suggests you'll only see power to the coils when CRANKING or RUNNING.

At least that's what I'm reading.

Let me know if you still don't have the service manuals for the V7III. The link to a readable diagram is above.

Kev

[Teddo]

Kev - When I back probe the red/brown wire on the coil connector I get a small voltage - like .05 when cranking ( maybe a bad probe contact) - but ya your right, it only powers up when cranking (or running)

[Kev m]

Kev - When I back probe the red/brown wire on the coil connector I get a small voltage - like .05 when cranking ( maybe a bad probe contact) - but ya your right, it only powers up when cranking (or running)

Well that comes from the Reg/Rectifier - which in turn gets power from the stator. So, I wonder if it's time to check the stator coils?

There have been a number of V7III's that burned their stators internally with shorts. Which would drop output to nothing or close to nothing.

The whole system sorta shuts down if it's not getting power when the crank is spinning.

[Kev m]

Kev - When I back probe the red/brown wire on the coil connector I get a small voltage - like .05 when cranking ( maybe a bad probe contact) - but ya your right, it only powers up when cranking (or running)

Just checking in - anymore progress?

[Teddo]

Kev I just got the new cps - it measures 924 ohms - a bit more than what's specified in the service manual 680 +- 15%(102). Should this be a concern? I can't find any independent resistance info on this sensor- Bosch 0261210 (same as the old one). Maybe the sensors changed since the manual was written?

[Kiwi_Roy]

Is there a crank position sensor on these bikes ? If so , and it's accessible , try removing it and checking for debris on it . Peter

Thats what I would be looking at

[Kiwi_Roy]

Is there a crank position sensor on these bikes ? If so , and it's accessible , try removing it and checking for debris on it . Peter

Thats where I would be looking, the sensor signals the ECU to fire up the coils, injectors and fuel pump, attach a small lamp to the injection relay contact.
The timing sensor is not a Hall Effect like the ABS Sensors its a very simple coil wrapped around a magnet should measure ~680 Ohms
Its a spare you should have, the motor is dead without it.

[Kiwi_Roy]

All the sensor does is pick up a gap in the teeth on the tone wheel which triggers the ecu to send signal to the coils.
I doubt both coils went bad at same time.

If there is no power to the coils it indicates the sensor is not sending pulses and the ECU is not turning on the power to the coils and injectors.
I installed an LED on the Injection relay the first change I got. The gap between the sensor and phonic wheel is also very important, I measure that by placing a blob of epoxy or JB Weld on the probe tip then bolting the sensor in place. After allowing time for the epoxy to set you cn take the sensor out again and measure the thickness of the epoxy with vernier callipers to get the gap setting.

[Kiwi_Roy]

Well the crank sensor appears to be open - I get nothing when probing for ohms across the 3 spades in the plug - I'll shop for a new one. But does that explain getting no voltage to the coils? Also why P0336 and not P0335?

This document describes the sensor on page 13, also shows the gap setting
http://www.dpguzzi.com/efiman.pdf

https://www.thisoldtractor.com/guzzi007/schematics/2015_V7_II_Racer_ABS,_V7_II_Special_ABS,_V7_II_Stone_ABS.gif
The crank position sensor sends pulses to the ECU, the ECU use these pulses to trigger the sparks and the injectors
When the ECU  is missing these timing pulses it turns off the injection relay to turn off injectors and coils.
A great aid in troubleshooting is a lamp monitoring the relay, I add one to all my injected Guzzi's (pin 1 - pin 2 of the fuel pump connector in this case.)

[Teddo]

Kiwi  -  Thanks so much for your help - the cps looks clean although the gear ring does look a little offset from the hole - like Smithswede  mentioned - did that ever get resolved? Air gap looks good. The reason i got a new cps is that my old one measured open. I'm  just wondering now why my new one measures 924 ohms and not 680? I do notice there's different types of cps on the Guzzis, mine mounts with one bolt where I see that others, I assume on older bikes, mount with 2 bolts - maybe the resistance changed with the upgrades? I really like the idea of that relay light, is there a picture of how you did that? Thank you for that pdf - great info!  You're right Guzzis are making us into electricians

[Kev m]

Sorry, late to the party today. Though I don't have the data to say whether or not you should doubt the new part for sure, I kinda feel it's more likely the impedance of the meter is different and the new one is probably good.

That said, I'm still curious if the issue isn't the CPS signal but possibly the stator not providing voltage for the coils. I thought the diagram suggested that the ECU only gets involved when breaking the ground to trigger the coil, but the power to the primary side came from the stator. No?

[Bulldog9]

That said, I'm still curious if the issue isn't the CPS signal but possibly the stator not providing voltage for the coils. I thought the diagram suggested that the ECU only gets involved when breaking the ground to trigger the coil, but the power to the primary side came from the stator. No?

And THIS is why I was asking if the plugs were wet or dry................ .

[Kev m]

And THIS is why I was asking if the plugs were wet or dry................ .

And again, I'm pretty sure they would have been dry either way.

No current to plugs and injectors = dry

No CPS signal = dry

If I'm reading the WD correctly the injectors can't pulse if the plugs can't fire, but I also believe the ECU WON'T pulse the injectors if it doesn't get a signal from the CPS.

[Bulldog9]

And again, I'm pretty sure they would have been dry either way.

No current to plugs and injectors = dry

No CPS signal = dry

If I'm reading the WD correctly the injectors can't pulse if the plugs can't fire, but I also believe the ECU WON'T pulse the injectors if it doesn't get a signal from the CPS.

Right, so if plugs were wet, it would likely be more in the power to coils, and less the sensor. That's all I was saying.

[Teddo]

Pretty sure the plugs were dry, bone dry now

[Kev m]

Right, so if plugs were wet, it would likely be more in the power to coils, and less the sensor. That's all I was saying.

I'm not 100% sure but I don't THINK so.

If the sensor fails the ECU will not provide ground to pulse the injectors OR fire the coils. So even if the fuel pump runs while priming and cranking, no pulsing of injectors = no fuel spray.

Since both ignition timing and fuel injection timing is controlled specifically based on engine rpm, no rpm signal because of a bad CKP would mean the ECU wouldn't try to activate either.

[Teddo]

SUCCESS! the bike runs...... it was the cps after all. Bugs me that it would fail so soon (<4k mi).  I'll be carrying a spare and a 10 mm socket in my back pack from now on.. Thank you guys for your guidance!
I'd like to see that Kiwi light.

[Kev m]

SUCCESS! the bike runs...... it was the cps after all. Bugs me that it would fail so soon (<4k mi).  I'll be carrying a spare and a 10 mm socket in my back pack from now on.. Thank you guys for your guidance!
I'd like to see that Kiwi light.

 .  . 

[Kiwi_Roy]

Well the crank sensor appears to be open - I get nothing when probing for ohms across the 3 spades in the plug - I'll shop for a new one. But does that explain getting no voltage to the coils? Also why P0336 and not P0335?

The crank sensor tells the ECU to power up the ignition coils and Injectors

[Kiwi_Roy]

SUCCESS! the bike runs...... it was the cps after all. Bugs me that it would fail so soon (<4k mi).  I'll be carrying a spare and a 10 mm socket in my back pack from now on.. Thank you guys for your guidance!
I'd like to see that Kiwi light.

Here you go, 3 lights, one for each relay under the tank, Start Relay, Injection Relay, Headlight Relay

I use type 194 miniature 12V wedge base lamps and solder the wires directly onto the base
https://www.superbrightleds.com/led-light-bulbs-universal-finder/wedge-base-bulbs/194-led-bulb-1-led-miniature-wedge-base
Type 194 have rectifier diodes inside so you dont have to worry about polarity just glue them into a suitable size hole. I also use them to brighten up any old guzzi dash.

[Kev m]

The crank sensor tells the ECU to power up the ignition coils and Injectors

Kiwi, cause you're better at this stuff than me. Is that REALLY what the V7III W/D says?

Sure looked to me like the stator will apply power to both anytime the engine is cranking (and only when the engine is cranking) and the ECU only applies ground (which I know if just two ways around a square and defacto applying ground "powers" up a circuit that is otherwise not powered because of lack of ground, so maybe semantics. But I'm curious if I'm reading that diagram correctly.

[Kiwi_Roy]

Can't find any voltage going to the coils. ( probed the spades in the connector with key on) Also tried swapping the relays. Huzo I checked all the fuses for resistance they looked good.

I don't believe you will see power on the coils just because the key is ON
the power to the coils is added when the ECU sees that the motor is turning over (injection relay closed)

[Teddo]

I don't believe you will see power on the coils just because the key is ON
the power to the coils is added when the ECU sees that the motor is turning over (injection relay closed)

Ya I was not getting power to the coil when the cps was busted. Thanks for the pic.