DT15 Ignition problem

[takoateli]

A friend's DT15 has an ignition problem, no spark period. If I put my volt meter on his induction coil (disconnected from the ignition system) I get around 15 VAC when the motor's pull starter is pulled. I've checked this with another DT15 and that seems right. When I check the voltage of the output of the little black box (the wires that go to the ignition coil, with the ignition coil disconnected) I only get a few tenths of a volt. I've checked this with a few other little black boxes here (none are known good, but at least two are suspected good) and I get the same reading. When I connect the whole ignition system and pull start the motor I get no spark. Measuring from one high voltage spark plug connection to the other I only get a few volts.

Does anyone have any troubleshooting tips I can perform using a digital VOM?

A known good motor should be back in a day and I can pull parts off that and start swapping parts. But I would like to know for future reference if anyone has any troubleshooting tips besides swapping parts.

Thanks!
Greg

 

[CharlieB]

Re: DT15 Ignition problem

Are you using a DVA adaptor with your volt meter to get these readings?

Straight voltage measurements are not nearly as reliable as load based measurements using a DVA adaptor, a broken yet abutted wire in a circuit may allow a small voltage with NO load, yet when measured using the DVA will fail and measure ZERO.

Buy, borrow, or build a DVA adaptor and repeat your tests.

DIY parts (cheap enough) and directions can be found somewhere in the iBoats forums, sorry, I don't have the link.

 

[takoateli]

Re: DT15 Ignition problem

Thanks! I had never heard of a DVA adapter. I did measure voltages in circuit with the wiring connected and it does then fall to zero.

Do you have a ball park figure for what kind of voltage I should see on the induction coil to black box wires? How about on the black box to ignition coil wires?

How about finding a low voltage (3-6V) AC wall wart power supply and using that to apply power to the ignition coil as a test? I tried tapping the wires to a AA battery but didn't get any spark. I think the AA battery doesn't have enough oomph.

Greg

 

[99yam40]

Re: DT15 Ignition problem

IT is not a good idea to check the output voltage on the secondary of the coils going to the spark plugs with a meter not meant for reading KV (high voltage) the primary inputs to those coils should be over 100V and the secondary would end up in the 1000s.
Your best bet is to pick up a service/repair manual for that motor. It will give the step by step instructions for testing and the specs. Along with the tools/equipment needed.

Here is a little info on troubleshooting CDI ignition systems
http://www.outboardparts.com/troubleshooting/printguide.htm

hope that helps some.

 

[takoateli]

Re: DT15 Ignition problem

Thanks for the post and thanks for the link to that info!

Yeah, I wouldn't have put the meter on the output of the ignition coil if it was someone else's. But since it was mine and I was sure there wasn't any high voltage being developed I wanted to really confirm what I was seeing.

Something is terribly amis. Given that I've tried probably-good (not known-good) black boxes and ignition coils I'm starting to question the pickup coil even though it's output looks good.

I'll post what I find.

Greg

 

[takoateli]

Re: DT15 Ignition problem - more info

Re: DT15 Ignition problem - more info

Today I used a working motor and got some measurements. Here's the difference between the two motors:

Working
Stator (pickup) open circuit output voltage: 35VAC
Stator (pickup) output current: around 35mA

Black Box open circuit output voltage: 35VAC
Black Box output current: around 35mA

Non working
Stator (pickup) open circuit output voltage: 15VAC
Stator (pickup) output current: meter indicates 0

Black Box open circuit output voltage: 100mV
Black Box output current: 0

On the non-working stator the resistance indicates in the megaohms. I wish I had checked that first. Obviously that should be very low, a few ohms at most.

I'm hoping the flexible leads of the stator are damaged and I can repair it.

Greg

 

[99yam40]

Re: DT15 Ignition problem - more info

Re: DT15 Ignition problem - more info

yes sounds like a open coil or wire

 

[takoateli]

Re: DT15 Ignition problem - more info

Re: DT15 Ignition problem - more info

yes sounds like a open coil or wire

Yeah, I should have found that a lot quicker. I think it's the leads because I find it hard to believe I didn't do a resistance check. I'm assuming that as the leads move there's an intermittent break in the continuity and when I checked resistance the contact was good. Or I just totally blew it and didn't do a resistance check.

I'm glad now I have some idea of what I should see as far as voltage and current coming out of the pickup

 

[99yam40]

Re: DT15 Ignition problem - more info

Re: DT15 Ignition problem - more info

those numbers are not what you would see in a manual They call for the use of the DVA adapter or peak reading voltmeter and is measured in DCvolts. But reading with regular meter on AC will give some reading to compare if you have a good one to compare to