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Discussion Starter · #1 ·
Hi.
I have a 2001 750 gsxr having the problem as written above.
So far I did the following:
1 - Took a coil + plug which fired at #1 and connected it to #2 and than to #4 -> Did not fired.
2 - Checked pickup resistance -> Found normal values as shown at picture.

1 - What is the problem?
2 - What do I need to do next?

Thanks a lot

61088
 

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I would have put #1 onto #2 and #3 onto #4 in hopes to see #2 and #4 to start working. Sounds like that's sorta what you did but only halfway and I'm not mechanical enough on these things to know if they are in pairs or not but that's why I would take both working ones and move it to non-working ones keeping it as if paired. Could you try that until the gurus here can tell you exactly what to do?
 

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Discussion Starter · #4 ·
hogcowboy - I did tried what you offered as I wrote. still only 1&3 give spark.

WintrSol - My wiring and diagram is different from what you post. All 4 coils has common wire and independent wire from the ECU (see picture).


Thanks for the posts
Any other ideas?

61106
 

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@hogcowboy - I did tried what you offered as I wrote. still only 1&3 give spark.
I'm lost then as that makes no sense to me. Unless something is shorting the spark for 2 & 4 even when you put the known working wires of 1 & 3 in 2 & 4. That is if you are saying you also moved non-working 2 & 4 to 1 & 3 and the non-working are now working. That's what it sounds like you did which makes no sense to me. I expected consistency and I'm not getting it.
 

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Discussion Starter · #6 ·
Maybe I described my test incorrectly.
  • I took a working coil+plug and pluged it to the wires of cylinder 1 (gray + white/blue). I press start and got a sperk.
  • I made the same for the other three. I got spark only at #3.
  • #2 #4 did not fired.
Hope I wrote it clear now.
Thanks
 

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Then, if it is wired per your schematic, and not the one I found, there must be open connections to the non-working coils; or a bad ECU. With a Volt meter, check that there is +12V at all coils on the Gr wires. If good, pull the connector from the ECU and verify that all four wires are fully inserted in the connector shell, and verify continuity (Ohms) from each coil to the connector contacts. Unless you have a drawing showing which contact holes they should be in, you will just have to follow the wires, by color, to the contacts; take notes.
 

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Discussion Starter · #8 ·
"pull the connector from the ECU and verify that all four wires are fully inserted in the connector shell, and verify continuity (Ohms) from each coil to the connector contacts"

- I did that. Continuity is OK

"With a Volt meter, check that there is +12V at all coils on the Gr wires "

- I haven't done that one but i saw all 4 gray wires connected together. I will check again.

- what about the pickup or CPS (crank shaft position sensor)? Is there a chance that the problem is there?
 

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All four gray wires may route to the same place, but the connection could still be bad to two of them. When you do your Voltage test, bend and twist them, especially where they come together, to see if the Voltage drops out.

If there is only one CPS to control spark for all four, I'm not sure it could cause two of four not to fire. A flaky ECU can, though. Is the firing order 1-4-3-2? If so, this is probably a waste spark system, where spark occurs at two cylinders at a time - one at top of compression, the other at top of exhaust, which is very common.
 

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Discussion Starter · #10 ·
Hi. Some updates:
  • A friend gave me a cdi. I connected it and still ignition was good at 1&3. I did saw some poor spark at 2&4.
  • I noticed that the stva (secondary throttle valve actutor) is not working well by sweep to fully open and to fully close when I opens the switch.
  • I disconnected it and held the butterflies open. I sprayed carb. cleaner and the motor manage to start and worked around 20 seconds. it wasn't stable but it did start.
  • I managed to start it with both cdi's so I believe they are not the problem.
  • After that i did not managed to start any more.

  • If the motor ran that means that at least 3 cylinders has sparks so I still can't explain the reason.
  • From what I red, a broken stva shall not cause starting probllems, just motor smooothness, is that true?
  • I remained confused about the source for the problem so I changed the thread tite.
 

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Discussion Starter · #11 ·
Hi hi.
Angry but happy. The motor finally startad. All it was a battery problem.
I never thought it can rotate the starter and not be strong enough to give good spark.

How embarrassing...
Thanks for the support and patience.
Bye for now

Sent from my Redmi 6 using Tapatalk
 

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Well thanks for letting us know. Glad you got it going. (y) (y) (y)
 
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