zeause Posted March 6, 2011 Share Posted March 6, 2011 Recently bought a 73 240z, pretty stock setup but on a L28. I bought it knowing it had charging problems, but didn't think anything of it. Well it came with 4 alternators, all bad. So i decided to do the 280zx 60 amp upgrade. Finished it and when i hook up my multimeter to the battery it's jumping around pretty bad. I also have tried taking the negative off the battery and the car will die. I had the alternator checked and it came out good. Im lost on what to do. I think i'll just start chasing wires tomorrow to see what I find, but I was wanting to know if anyone else has had this problem and would know where to start. Thanks, Casey Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted March 6, 2011 Share Posted March 6, 2011 sounds like what my hilux was doing for a while, which was a case of replacing the voltage regulator to fix the problem. Were the early alts External or Internal regulation? My 280ZX Haynes manual shows an internal regulator on the ZX alts, that should have fixed a bad regulator on the Z... My first step would be to thoroughly attack each and every ground surface with a wire brush and rebolt them up again. Use connector cleaner on each and every plug, clip or jack which is in a housing where you can't get a wire brush in. Remember these are OLD cars with lots of time to gunk up. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 6, 2011 Share Posted March 6, 2011 Finished it and when i hook up my multimeter to the battery it's jumping around pretty bad. I also have tried taking the negative off the battery and the car will die. I had the alternator checked and it came out good. What does jumping around pretty bad mean? What is the range of jumpiness? I moved my S wire from the battery positive to the starter lug to see if it would smooth my dash voltmeter's needle jumping around. It did but I can't really explain why. ZX alternator in a 1976 car. Quote Link to comment Share on other sites More sharing options...
zeause Posted March 7, 2011 Author Share Posted March 7, 2011 It was jumping from 9v up to 20v. I pulled it off today and the alternator turned out to be bad. It was only a week old from autozone. I tested the s and l connections because they got hot and started smoking. With the T shaped plug unhooked I tried to jumper a 12v+ to both the s and l spots. It started smoking, I hooked the multimeter to the s hookup on the alternator spade and it was actually putting off 12v. Im guessing something in the alternator fried because it shouldn't have been putting off any power. Quote Link to comment Share on other sites More sharing options...
Dro21 Posted March 7, 2011 Share Posted March 7, 2011 I would check the grounds and the voltage regulator like kiwi said.I had the same problem with my mustang and it ended up being the voltage regulator. Quote Link to comment Share on other sites More sharing options...
misterZ Posted March 8, 2011 Share Posted March 8, 2011 (edited) There was a nice write-up to delete your ext regulator by installing an alternator from a ZX. I want to say it was from AtlanticZ but here is a link that essentially explains the same process. When I get home, I think I saved the link w/ schematic to convert to the ZX alternator but you have to install/splice a couple 'loop' wires to (I think) bypass the ext reg connections: http://zhome.com/ZCMnL/tech/280Alt.html It was the first mod I did on my `77 and works like a champ! No bouncing voltage needle or dimming lights. EDIT: Use this link, follow the steps; however, I believe MSA sells the loop plug you need for the the 240Z: http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html Edited March 8, 2011 by misterZ Quote Link to comment Share on other sites More sharing options...
zeause Posted March 9, 2011 Author Share Posted March 9, 2011 The alternator tested good a few days ago, then i checked and the alt fuse was blown. Replaced the fuse and had the alternator tested again, do to it putting out 12v at the s connection on the alternator itself. Turned out to be bad after all. So I replaced it and its charging great now! Driving it to work for the first time tomorrow! Quote Link to comment Share on other sites More sharing options...
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