Help with thunderbolt iv ignition no spark

[blue89turbo]

Hi guys.

My boat wont start so I followed the flow chart for the thunderbolt iv ignition and it pointed me to a new coil. I bought one but I still have no spark so the next step is a new ignition module. Before I spend more money I have a question. When I look for 12v at the coil I get 12v on the pos on the coil and a ground but not on the pos and neg on the actual coil. Is this normal? Any other ideas?

Thanks

 

[achris]

Re: Help with thunderbolt iv ignition no spark

A few more things to check before you go spending on parts. I have a TB-IV system in bits at the moment and I have measured a lot of stuff with meters and an oscilloscope, so I am fairly familiar with them.

What you are seeing on the coil is correct... With the tacho wire disconnected from the coil -, and the shift interrupt wire disconnected from the sensor....

Do these tests.

1. Measure for 12 volts on the coil + (already done, 12V)
2. Measure for 12 volts on the white/red wire on the distributor sensor.
3. Remove the dissy cap and look at the window across the sensor. Measure the voltage at the white/green wire on the sensor. With the window closed (the metal across the sensor), it should be about 4.5 volts, with the window open, 0 volts. Check the voltage with the window in both places....

If you do have those voltages, and you have replaced the coil with A KNOWN GOOD ONE, then yes, it does look like the module....

Chris.......

 

[blue89turbo]

Re: Help with thunderbolt iv ignition no spark

Thanks for the help Chris.

I will check those things and let you know what I find.


Thanks

Jason

 

[blue89turbo]

Re: Help with thunderbolt iv ignition no spark

Ok. So I took the cap off and tried to measure the voltage. I really couldn't get a defined 0 and 4.5v on the green/white terminal. I was getting something like 3.8 when closed and maybe 1v when open? Does that make sense

 

[achris]

Re: Help with thunderbolt iv ignition no spark

That does sound like the module had failed...

 

[blue89turbo]

Re: Help with thunderbolt iv ignition no spark

Ok thanks. So you are pretty sure that is a sign of a bad module then? Since I have to store the boat for winter in the next week or 2 I may just store it as is and buy the part in the spring...

 

[achris]

Re: Help with thunderbolt iv ignition no spark

One last test I would do... Don't think it's going to make much difference to the end result.

Measure the voltage at the white/red, should be 12 at all times. Remove all white/green wires from the sensor and measure the voltages on that terminal again. If you now get your 0 to 4.3 swing, that is definitely the module.

Now, with all the white/green wires off, pull the HT lead out of the distributor cap and stick a spark plug in the end. Lay the spark plug on the engine and (with power on) strike the white/green lead that comes from the module on a good ground as quickly as you can... I doubt you'll see a spark... That would be as close to conclusive as I can get you. The only other thing to check are all the grounds. To module and distributor body, and sensor frame....

Chris........

 

[blue89turbo]

Re: Help with thunderbolt iv ignition no spark

Ok maybe ill still check this out tonight thanks.