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4th Gen has no spark


n2red
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Guys.... I have a 1997 VFR that won't spark Was running find then died.... not like turning off the switch, but started missing, then nothing.,  I have tools, good mechanic skills, reference manuals, and, thanks to this problem, no more hair.

This is a well maintained bike so neglect really isn't a factor. I have done dilligent wire tracing, tried three (3) different ICM's, replaced the pulse sensor, replaced coils, getting continuity, where specified...pulse sensor is sending 4-5 volts, battery is new (fully charged before testing), side stand checks good, neutral switch is good, but I'm only getting about 65-70 volts coming from the ICM to the primary side of the coils.... (Manual says 100 VDC minimum). There is no spark on any plug. I need another set of eyes with more experience looking at this.

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Have you confirmed Volts and Grounds at the ICM connector? I know you've stated you have checked the Neutral and Sidestand switches, but have you confirmed their Grounds are getting to the ICM?

Grounds must read zero ohms back to the Negative Battery Terminal, not just to frame!

1 - Do you have a solid Ground on the Green wire at the ICM connector?

2 - With Ignition to ON and Kill Switch to Run, do you measure battery voltage between the Green wire and the Black/White wire at the ICM connector and all Black/White wires of the 4 coils?

3 - With bike in Neutral are you seeing a solid Ground on the Light Green wire at the ICM?

4 - With the Sidestand Up are you seeing a solid Ground on the Green/White wire at the ICM?

5 - Measure the two Pulse Generator coil resistances, make sure they are in spec 200 - 400 ohms each then with the ICM plug removed make sure you are seeing the same resistance values at the ICM connector, note Yellow wire is common so measure White/Yellow to the Yellow then White/Blue to the Yellow. Refer the attached drawing.

 

Is your Ignition System layout as per the drawing attached?

Good luck.

IMG_0974.PNG

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Yup... layout is the same as I've been using to test. Pulse gens are ohming out at 311 ohms....and between 4-5 volts on peak voltage. All wires at the ICM connector read the same as the values that are found at the respective, and pass the wiggle test at the ICM connector. Even disconnected all the ground wires from their respective attaching points, ganged them them all together for a massive "danged sure ground" at a known hardpoint... Nada...  (and thanks for the fast response BTW)

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Ummm. It sounds like you've confirmed step 5 and maybe step 1. But how about steps 2,3 and 4?

 

What voltage are you seeing at the ICM on the Black/White wire while cranking?

 

You could try only having one known good coil connected. See if you get a spark from that.

 

"I'm only getting about 65-70 volts coming from the ICM to the primary side of the coils.... (Manual says 100 VDC minimum)".

Where does the manual state this? Are you measuring this with a peak voltage adaptor?

If you've replaced the coils and ICM and your interconecting wires between the ICM and coils are good then that test really doesn't mean much. The ICM switching transistor for each coil grounds and then opens the coil primary. The 12v supply and proper ground for the ICM are more important in your case. Along with the ignition pulse gens trigger inputs and the enable/disable logic grounds from Neutral or Sidestand switches.

 

I only have the 90-96 VFR750 Service Manual. (Also....I've never owned a 4th gen.)

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Thanks for the insight... I have the '90-95 Honda Service Manual  which primarily gives resistance values and a diagnostic flow chart. I also have the 1997 Honda Service Manual for the VFR750F. It deals more with actual performance parameters. ( And the same circuit layout as the other manual) ...It says (on page 17-5, when checking the 4 ignition coil primary leads from the ICM), "Peak voltage: 100 V minimum."

I am using a Klein MM400 multimeter and an Ideal 61-310 multimeter, both having an impedance of 10 megohm/DCV, with a peak voltage adapter.

I will recheck again (because I'm an old man and I forget things a lot) the cranking voltage at the primary side of the coils. As I remember, It does not drop during cranking, which could be a short in the primary coil.

Thanks, and clearly, you know your stuff... Dan

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While grasping at straws, I did take both the side stand and neutral switch off the circuit and just let the ICM see a ground. Still nothing. I'm open to whatever is necessary to hear it run. Once I can see where the prob is, I can reintroduce the good parts back into the system. Right now, no configuration I can come up with works. Thoughts?    Dan

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Voltage on the Black/White wire is 12.8 dropping to 10.8 while cranking.... coils are ohming at 3.4..... with a confirmed good ground... and sidestand and neutral switch confirmed good grounds. Battery is new and fully charged at the beginning of this test.  Pulse coils are ohming at 311 ohms, with a 4-5 VDC pulse... still no spark....Dan

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Process of elimination. You confirmed that ICM is known good ( new or have you hear it running in another bike?) Now I would concentrate on clean inputs to the ICM. Clean power, clean ground. I see you have tested pulse generator extensively, check terminals with spare male terminal and make sure there is proper  amount of friction and no corrosion. 

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3 hours ago, n2red said:

Voltage on the Black/White wire is 12.8 dropping to 10.8 while cranking.... coils are ohming at 3.4..... with a confirmed good ground... and sidestand and neutral switch confirmed good grounds. Battery is new and fully charged at the beginning of this test.  Pulse coils are ohming at 311 ohms, with a 4-5 VDC pulse... still no spark....Dan

Manual says pickup-coils should be 450-500ohms @ 68F. But the next page it says 200-400ohms.... ???

Make sure wires are OK, by measuring crank-triggers at ICM connector.

If wiring is broken on way to ICM, signal doesn't make it.

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8 hours ago, n2red said:

Thanks for the insight... I have the '90-95 Honda Service Manual  which primarily gives resistance values and a diagnostic flow chart. I also have the 1997 Honda Service Manual for the VFR750F. It deals more with actual performance parameters. ( And the same circuit layout as the other manual) ...It says (on page 17-5, when checking the 4 ignition coil primary leads from the ICM), "Peak voltage: 100 V minimum."

This seems very odd as bike uses inductive coils (not CDI):

 

1. ignition-switch powers ignition-coils with +12v from battery, primaries are "live" with power full-time with charged EMF

2. ICM then grounds other side of primary coils to dump field and generate HV at secondary

 

There really shouldn't be any voltage coming out of ICM on any of trigger wires...

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Here's the "100 volts minimum I mentioned...... Since the Black/White wire is a constant voltage from the battery and only drops slightly while cranking... Did I err?

 

 

Hereimage.thumb.jpeg.3841f88ef6c7dd200154021fd2ded656.jpeg

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That certainly looks like test for CDI ignition.

Pulsing +100v into coil that's already charged with +12v isn't good way to fire coil.

Such short duration and low-amperage will be negated by +12v high-amp power from battery.

I suspect your 1997 manual may not be matched to your bike.

I found that same test page 17-5 in the '98-01 VFR800 Service Manual
https://www.vfrdiscussion.com/index.php?/files/file/171-98-01-honda-vfr-service-manual-optimized-bookmarked/

 

What voltages did you measure for Grum's test#2 above? Should have 5 separate readings.

 

Quote

2 - With Ignition to ON and Kill Switch to Run, do you measure battery voltage between the Green wire and the Black/White wire at the ICM connector and all Black/White wires of the 4 coils?

 

Next step is to test ignition-coil secondary's output. Do you have spark-tester to insert into plug-wires? Or you can just insert spare plug into plug-wire and ground case of plug and crank.

 

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Battery voltage at Black/White and Green (Ground) is 11,9  (Battery is charging)

Voltage on all four coils is the same... 11,9..

I' initially used my inductive timing light, which showed "No Spark".... then, with a grounded spark plug... which also did not spark.

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What's part# on your ICM?

 

I think issue here may be you've got mixture of VFR750 and VFR800 parts and different manuals all for one bike.

You've got inductive coils for VFR750, yet ICM seems to fire it like VFR800

Your ignition-coil test seems to fail VFR800 manual.

But chances of all 4 coils going bad at once is highly unlikely.

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Gut feeling is.

1 - You possibly could have a poor socket to pin contact between main plug and ICM.

2 - ICM is not seeing trigger pulses from Pulse Gens.

3 - ICM is faulty!

When replacing the pulse gens. Are the pickups spacing adjustable relative to the starter clutch? In other words could the pickups be too far away from the pulser bumps on the starter clutch outer? Grasping at straws a bit!

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Oh, Im hip on "grasping at straws"   The pulse gens are putting out a good 4-5 V.... according to "THE MANUAL" the minimum is .7 V..... There appears to be no degradation of the signal because that same value is read at the ICM connector.....  I did not see where there was much adjustments for the pulse gens... three bolts out-- three bolts in..

 

I understand the possibility of #1 above... if that IS the case, then no ICM will work properly until you rewire another connector in place.....

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Is there any chance you can measure the diameter of the ICM pins. Then finding something, perhaps the end of a very small drill exactly the same diameter and use this to insert into each of the sockets to feel the socket retension for each socket? Assuming they are of course round pins and sockets!

 

Also a close inspection of the ICM plug. Is there any sign of corrosion, oxidization, burn marks etc?

 

More straw grasping!

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Have you tried testing each coil for a spark separated from the ICM?

 

I'm guessing that if you rig up a 12v lead to the coil primary (or simply unplug the ICM but using the existing Black/White wire 12v to the coil primary) and you have another wire connected to the primary ground side,  grounding and ungrounding the ground side wire should induce a spark at the spark plug.

Doing this is the same thing that the switching transistor in the ICM is doing, switching between ground and no ground on the coil primary ground.

 

This will at least verify all coils and HT leads are functional.

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I have NOT thought of making a coil "tester"  ... I may have to try that...  nothing ventured........ I've tries most everything else... and of course, thanks ,guys for your insights into my problem..Dan

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