No Spark...need help

[HakosukaJD]

All,

Been through the search...maybe I'm not covering the right string or maybe I just need more clarification...

 

Took the engine out to get it cleaned up and to clean up the wiring a bit. I was extremely careful about marking all leads and terminals.

 

When I put it back together, all the electrical works fine....with the sole exception of the ignition system (most important part...figures)

 

I'm getting a no spark condition.

 

Here's the rundown.... L28 running an Ultra Transistor Ignition Module, stock dizzy (didn't take it off the block when I pulled the engine.), MB2 Coil. No spark condition tested with a timing light, and then plug pulled and touched to ground while cranking. I get nothin.

 

At first glance, the coil appears to be fine (.7 Ohms across the primary, 5kOhms across the Secondary)

 

When I turn the key to the "on" position, I'm only getting 9V at the + Coil Terminal (to battery ground), and I'm getting .5V to the - coil terminal to ground. When I remove the power lead from the coil, it reads 12.X (whatever battery is reading at the time). Should I be seeing this drop? Am I "leaking" voltage somewhere? I haven't found any bad/shorted/melted/overheated wiring traced back to the Transistor module and/or the switched power solenoid. Anything additional or in particular I should be looking at or measuring?

[go 260z]

Sorry to hear about your problem, because it sounds like mine.

My car is a 1974 260z with all original wiring and components. It has been sitting for 26 years because of this intermitant electrical problem. Two months ago I decised to put her back on the street. After all the mechanical were reworked I am back into the electrical. I have all the lights working but NO cranking. So far, everyone want to condemn the interlocking relay or unit and the transistor igintion unit. That is my chore today....How is your problem working out ??

[HakosukaJD]

Sorry to hear about your problem, because it sounds like mine.

My car is a 1974 260z with all original wiring and components. It has been sitting for 26 years because of this intermitant electrical problem. Two months ago I decised to put her back on the street. After all the mechanical were reworked I am back into the electrical. I have all the lights working but NO cranking. So far, everyone want to condemn the interlocking relay or unit and the transistor igintion unit. That is my chore today....How is your problem working out ??

 

 

Unfortunately, its not. Haven't had time to try to tear everything down...was hoping for a bit narrowed search from forum help. It will probably end up being a project over Christmas break.

 

Also unfortunately, my transister unit (Ultra) is a Japanese Domestic model, so I have no diagrams or info on how to troubleshoot using a voltmeter....

[go 260z]

Today I disconnected the transistor unit and my voltage, at the coil, went up to 12.

It still is not cranking so this is my next step. I have enlarged the wiring diagram by 185% and will white out all the wires that a working. I hope that will get me to a managable number of wires to search for my shorts

[NewZed]

The "cranking" circuit should be fairly simple to follow out. It just puts power to the small wire on the starter, when you turn the key to Start (it does a few other things but that's the basics). The ignition circuit is on when the key is On, that's why you can start an engine by putting a car in gear, rolling it and engaging the clutch, with the key at On. You can also short the big terminal on the starter to the small one (temporarily) to get the engine to crank, or start if the key is On (make sure it's not in gear if you try this).

 

If you find that the car will start by shorting the starter, but can't figure out the wiring problem from the ignition switch, you could wire in a push button starter, either temporarily or permanently.

 

Start at the small wire on the starter and work your way backward if you're having a "cranking" problem.

 

p.s. I had a Start problem for a while when my key would not turn the "insides" of the electrical portion of the ignition switch far enough to hit Start. I had to bend the little tab at the back of the switch in the direction of rotation to get it do its job. But see if you can short your starter first before you go to that.

 

Edit - the above is for go 260z's problem. It sounds like HakosukaJD has something else. 9V at one side and 0.5 at the other side, all the time, sounds like you have current flowing, which should only happen when the ignition module tells the coil to fire. Otherwise it should just sit there at 12 and 12. You might have a short between the coil and the module. Or a bad coil (maybe). Was your coil getting hot while you were measuring?

 

I'm no electrical wizard so use these ideas carefully... I can take a beating if someone wants to shoot me down.

Edited December 3, 2010 by NewZed

[go 260z]

Making progress...Thanks for your ideas.

When I removed the igition switch plug from the switch I found some corrosion and looseness between the contacts. When that was cleaned up and tightend....it now turns over with the key.

I have purchased the new crane xr-700 igition system from z-source and will not try to start the can until that is installed

[HakosukaJD]

Silly me.

 

Problem fixed.

 

I pulled the engine and made a number of wiring repairs (prior to the no spark condition). The repairs were sound. The problem was that I believed because I had rebuilt the wiring surrounding the ignition system using heavier gauge and more modern connectors, I thought it would eliminate the need for a grounding strap from the dizzy to the battery (or grounding plate....using cover plate for mech fuel pump point). Not so much.

 

After reading someone else blog regarding a no-spark condition repaired by a ground strap directly to dizzy, thought I'd give it a try. Car fires right up.

 

Thanks for all the other ideas anyway....more information is always good in TSing future problems bound to occur....