Type III Thunderbolt - Distibutor C.D. Ignition

[english boy]

I have a 65 Merc Blueband with the above ignition system. I posted a problem a while ago saying it would not spark. I then got it to spark, then it stopped, then it started, now it has stopped!!<br /><br />When it lasted spark the engine ran (for the first time in years) and sounded nice. After reading this site and my manual I think it might be the trigger.<br /><br />Here comes the questions....<br />Is my understanding of the ignition system correct(I have learnt this during this last month)<br /><br />Flywheel turns a pulley on top of distributor, which sends a signal (trigger) to switch box, which sends a higher current to coil, which goes back to distributor to go to the plug leadsd?<br /><br />When the engine was working I had a current to 2 of the 3 wires which came from the distributor to the switch box and now it has stopped running I only have current to 1, which is the top wire as you look at the switch box.<br /><br />IS THERE A WAY TO TEST THE TRIGGER or have I already done it!! Which is the trigger wire??I have read that the trigger is a common problem and can cause on off running problem. CAN I REPLACE THE TRIGGER?<br /><br />Any comments and advise would be great. ( I do apologies for the length of this post!!)

 

[ledgefinder]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

The only solid way to test the trigger is to observe it's output with an oscilloscope or peak-reading voltmeter. You can measure the resistance of the trigger. However, it's possible for a trigger to have normal resistance, and still not be generating enough signal. CDI's website has their troubleshooting guide, which gives reference values for output & resistance for your trigger (www.rapair.com). Maxrules has wiring diagrams (www.maxrules.com).

 

[english boy]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

Thanks ledgefinder, can get an oscilloscope from work.

 

[english boy]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

Had had a look at CDI's website but can not fnd a troubleshooting section? <br /><br />IF the trigger has gone can I just change that or is it a new distributor I will need?

 

[ledgefinder]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

Yeah, think they may have pulled it.<br /><br />If you post an email address, I'll email it to you eventually. Otherwise, LOTS of people have copied at least sections of if - try a Google search with "mercury ignition troubleshooting".

 

[english boy]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

This is my email keironpowell@aol.com will now TRY and find it on google!! cheers

 

[english boy]

Re: Type III Thunderbolt - Distibutor C.D. Ignition

I think I have could it at www.tenkillermarine.com<br /><br />Says I should have 9v at black and white wire then 2.5v using a DVA across black and blue at switch box. Is this what I am looking for?<br /><br />Could you explain what a DVA does? Is this why I will need the oscillascope (excuse the spelling please!)