1985 Suzuki DT30 No Spark when cranking

[niegelp]

I have an '85 DT30 I've been working on for a while. Customer brought it in because it would crank and crank but not start. The only way I could get any spark out of it at all was to flick the key switch back to the off position, then to the run position while the engine is still turning. Confusing, I know. I have checked every electrical system, double checked my grounds, tested continuity on the kill wire, everything.


I had a few calls into the Suzuki dealer, he said to test it with a different key switch. Didn't change a thing. I had a CDI lying round and swapped that out, still no change.

I am wondering if anyone has had a similar problem to this at all. This is perhaps the weirdest problem I have run into.

 

[99yam40]

Re: 1985 Suzuki DT30 No Spark when cranking

test inputs and out puts of CDI while cranking would be my thoughts.( voltages)

Disconnect control cable at motor to see if that will allow spark while cranking

 

[TwoRivers]

Re: 1985 Suzuki DT30 No Spark when cranking

I have an '85 DT30 I've been working on for a while. Customer brought it in because it would crank and crank but not start. The only way I could get any spark out of it at all was to flick the key switch back to the off position, then to the run position while the engine is still turning. Confusing, I know. I have checked every electrical system, double checked my grounds, tested continuity on the kill wire, everything.I had a few calls into the Suzuki dealer, he said to test it with a different key switch. Didn't change a thing. I had a CDI lying round and swapped that out, still no change.

I am wondering if anyone has had a similar problem to this at all. This is perhaps the weirdest problem I have run into.

Agree this is a weird problem. Just went through a similar situation with an 87 DT30.
If you changed out the cdi and still no spark you can probably rule that out. I've read many times and had Suzuki mechanics tell me that the cdi rarely goes bad.
Check the ground area where the cdi and the other coils all ground to the same bolt. Do whatever you have to do to make sure all three wires are getting a good ground.
I assume you tested the coils under the flywheel with an OHM meter?
If not you need to do that. Let me know if you need specs.
If all is OK you'll need to remove the flywheel and check for dirt, corrosion, broken wires etc. Clean everything up and see if you get spark.
In my case everything tested OK; cdi (secondary), ignition and lighting coils. I ended up replacing everything and still no spark. Went back to the ground area and moved things around a bit and added another washer and boom. Been running and starting since with zero issues.
Can't say 100% but I think the problem was in the ground all along.
Good luck.