jhm Posted September 3, 2009 Share Posted September 3, 2009 OK, gents.....I've searched high and low; and while other folks have had similar-sounding problems, I haven't found any info on my specific dilemma. For example, TrumpetRhapsody was having identical symptoms with his car, but that turned out to be the ballast resistor -- N/A to me because I've got a SBC w/ GM HEI (and obviously, no ballast resistor). In short, my engine will crank just fine when the key is turned to the "Start" position, but it won't fire up. However, when the key is released to the "On" position, the motor will usually fire (and run fine from then on). For some crazy reason, I'm getting good spark in the "On" position but not in the "Start" position! I have a 1974 260Z w/ a late '70's SBC equipped with a GM HEI distributor. I recently upgraded the HEI with Proform ignition module and high output coil. I had previously removed all of the engine compartment relays, so my problem shouldn't be related to a bad relay (at least any of the relays under the hood). So any ideas??? Even though I don't think it would be a bad ignition switch (since it cranks the engine just fine), I've dismantled and cleaned the switch -- it didn't help. Again....good battery, supposedly good distributor, and good spark in the "On" position, but no fire in the "Start" position. Help!! Thanks in advance to all. r/John Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted September 3, 2009 Share Posted September 3, 2009 One thing I noticed with the 260z is that pretty much all accessories lose power in the start position. When wiring up megasquirt I never could find a wire that would get switched +12v in both the "run" and "start" positions. I don't know anything about your ignition system or wiring layout, but it's possible you've given it a switched +12 that goes dead in the start position. If you can't find one that doesn't, you might have to wire a switch for your ignition system like I did for megasquirt. Quote Link to comment Share on other sites More sharing options...
jhm Posted September 3, 2009 Author Share Posted September 3, 2009 Sorry, guys....I should've also mentioned that this problem only recently popped up (after I replaced my cruddy old fusible links with circuit breakers). TR has already given me some helpful info, but I'm still open to any and all suggestions/tips/advice/recommendations! Quote Link to comment Share on other sites More sharing options...
jhm Posted September 15, 2009 Author Share Posted September 15, 2009 For anyone that's interested, it turned out to be a bad ignition switch. I tested the unit, and determined that the ignition wasn't getting power while the switch was in the "Start" position. The attached schematic was quite helpful -- I believe it applies to all S30s and 130s, since MSA carries the same ignition switch (electrical portion) part number for years 70-83. I was able to get a replacement unit (used) from Z Car Source for $16....only needed the electrical portion of the switch, not the keyed part. Strange that my switch decided to crap out at same time as my fusible links....don't know if there's a connection there somehow. Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted September 15, 2009 Share Posted September 15, 2009 Hmm makes me wonder if that's why I couldn't ever track down my ign +12. Thanks for the update! Quote Link to comment Share on other sites More sharing options...
DuoWing Posted October 12, 2009 Share Posted October 12, 2009 I'm beginning to wonder if this is my issue. My car seems to work fine in the ON position, but it seems like it's kind of random where it will start quickly, take a while, or just plain not start when in the Start position, but has no issues cranking. How did you test the switch, via the connector that hangs down under the column? Just checking to see if at some point it would drop power? Quote Link to comment Share on other sites More sharing options...
jhm Posted October 14, 2009 Author Share Posted October 14, 2009 To test the switch, remove it from the combination switch mounted on your steering column. (I suppose you could actually test the switch without removing it, but that would require some really painful contorted time under the driver's side dash!) Start by removing the plastic cover on the steering column. After it's off, remove the 4 phillips head screws that secure the combo switch to the steering column. After that, you'll have the two sides of the combo switch hanging down off your naked steering column. Unplug the 6-position electrical plug from the ignition switch. Remove the two little screws holding the switch's electrical portion to the keyed portion of the switch. The electrical portion is a small silver barrel with 5 prongs on one side, and a rectangular slot on the other. You can now test your switch. Using the schematic in my Sep 15th post, test continuity of your switch in each of the 4 positions: Off, Acc, On, Start. You'll probably need an assistant to test the switch in the 'Start' position (due to the fact that the switch is spring-loaded in 'Start') -- one person can hold the switch in the 'Start' position while the other person tests the leads on the back of the switch for connectivity. If the continuity in your switch does not match the schematic, then your switch probably needs to be replaced. My switch turned out to be bad because I had no connectivity between the ignition ("IG") and the battery ("B") in the 'Start' position -- meaning that I had no juice going to the ignition while the starter was cranking the engine. Weird, huh? Like I said in my earlier post....it's an cheap and easy fix to replace the switch (electrical portion only). $16 from Z Car Source. New switches are available from other sources, but keep in mind that many of them may try to sell you a complete switch (electrical plus keyed portion) for more money. Good luck and happy motoring! Quote Link to comment Share on other sites More sharing options...
DuoWing Posted October 15, 2009 Share Posted October 15, 2009 Thanks for the tip. Luckily if I do require a replacement for the time being my 280ZX that I took the motor out of has a known working ignition switch. So I could probably swap that in as like you said, they seem to sell the same part for all the L-series Zs. Quote Link to comment Share on other sites More sharing options...
DuoWing Posted November 4, 2009 Share Posted November 4, 2009 Well went to go pull the barrel out of my car. Anyway I removed the electrical connector from the switch and I noticed that the barrel was held in by one screw and it was loose and I could kind of rattle it around a little. Anyway I took it out and I pulled the other out from my 280ZXT. I was messing with them, they seem alright, but the one from my 76' which has starting issues seems finicky. Like it seems like it'll have power to ignition when starting, but kind of sketchy, and then when you let off to go back to ON it won't have continuity to the ON position unless I move the position of it just slightly. Where the other one from the ZXT had no real issues. So I'm going to throw the one from my ZXT in there which had no issues with starting or the ignition, make sure it's held on with both screws tightly, and try. Hopefully that takes care of my problem. Thanks for the info in this thread! Very helpful! Quote Link to comment Share on other sites More sharing options...
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