potential alternator issue

[quick.msp]

Hey guys,

So I have been working through issues with my car and thanks to the forum I fixed my fuel pump wiring, got my real main seal issue repaired. I thought I was in the clear, went for a good 40 mile drive, turned the car off for 7 hours, went to start it and barley turned over, battery was low.

I do not think there is a draw anywhere, for some reason I suspect the alternator so I did some testing and want to see if these numbers are low. Engine is ls3 crate with 1,500 miles on it but sat for 3-4 year, new napa battery.

Car off: 12.5V
Car running: 14.6V
Full load (fans, radio, blower) 13.95V

[Cobranut]

Hey guys,

So I have been working through issues with my car and thanks to the forum I fixed my fuel pump wiring, got my real main seal issue repaired. I thought I was in the clear, went for a good 40 mile drive, turned the car off for 7 hours, went to start it and barley turned over, battery was low.

I do not think there is a draw anywhere, for some reason I suspect the alternator so I did some testing and want to see if these numbers are low. Engine is ls3 crate with 1,500 miles on it but sat for 3-4 year, new napa battery.

Car off: 12.5V
Car running: 14.6V
Full load (fans, radio, blower) 13.95V

14.6v at idle sounds pretty good.
The 13.95v with load should be ok, as long as it comes up to 14.5 or so with a little rpm.

I'd check for any loose connections, and have your battery load tested.

[quick.msp]

Thanks I will check both.

Battery was purchased brand new in 2022.

When the car did not start, it was weird because it didn't sound like the fuel pump was coming on, and the wiper which was left on was moving very slow. (I'm assuming the wiper being left on, but key off would not draw any power?)

When I went to turn the key the engine did not even turn over, it just clicked. I tried a few times and nothing, I waited about 5 minutes and the car did eventually start but turned over slower than usual.

[jwvand02]

Did you drive more after the car struggled to turn over and then measure those voltages?

[AHarada]

Did you test to see if there is a parasitic draw? It's fairly quick and easy to do with a multimeter. I have had multiple parasitic draws in my FD that I had to repair. Your static voltage with the car off isn't super strong, so you could definitely have sulfated the battery with a draw.

Is your wiring from battery to alternator/starter and grounding wiring all solid? I have encountered bad terminals that caused voltage drops that were worse with hot starts.

[kinger]

Your voltages look spot on to me and match my 2 year old optima red top. 

Also check the clutch interlock switch above the clutch pedal.  Its referred to as the infamous "click click start" issue happens to both rotary and swapped cars.  I finally did a bypass by unplugging it and sticking a wire in there in a u shape to keep continuity and it fixed all start issues.  I actually forgot I did this 3 years until just now writing this.  My plan at the time was to get a new switch for it but they are not reliable even new so most just bypass it, but you MUST make sure you are in neutral as the car will now turnover in gear and attempt to roll ahead. 

[jwvand02]

Did you test to see if there is a parasitic draw? It's fairly quick and easy to do with a multimeter. I have had multiple parasitic draws in my FD that I had to repair. Your static voltage with the car off isn't super strong, so you could definitely have sulfated the battery with a draw.

Is your wiring from battery to alternator/starter and grounding wiring all solid? I have encountered bad terminals that caused voltage drops that were worse with hot starts.

This is ultimately my best guess too, although it doesn't 100% line up. I have worked on 3 different swapped cars that had intermittent full-car electrical issues that came down to large-gauge wires crimped with a hammer, and like you said the issues often cropped up only once everything got nice and hot.

I've also seen two LS alternators now that have the main post threads half-stripped out so that the connection is intermittent.

[quick.msp]

OK I am getting to the bottom of this random no start issue.

I think the battery and alternator are fine because after a few tries for turning the key and just hearing a click, the car starts up fine even sitting for a few days, I think the issue is in the stock wiring, see links below:

https://www.norotors.com/index.php?topic=23885.0

https://grandmighty.github.io/grandmighty/2016/03/starter-booster-relay/

So I bypassed by clutch switch, and alarm system hoping this would help but it did not.

My next step is to build this relay to help supply constant voltage to starter solenoid, has anyone done this? Im assuming everyone with a swapped rx7 will have these issues.


So I ordered a hella 40amp relay with 5 pin harness, i followed everything on this grand mighty write up and wire 87 that connects to terminal S on the starter.

I was surprised this to be a small gauge wire, is this only passing voltage signal to the solenoid? and all the voltage is running through the large wire on terminal B? I know 87a is a spare and its a large gauge wire, please confirm if anyone has done this that was my only concern before I install, thanks.

Position 86 to Ground ring terminal on starter bolt
Position 30 to Terminal B on starter 12V
Position 85 gets spliced into the OEM black / red mazda wire that used to go to terminal S (this now acts as the signal wire)
Position 87 is the one I have in question, this wires into terminal B on starter solenoid and I was surprised this was with the smaller gauge wire.

[driftnfb]

87 goes to starter 'S' signal
85 ground (make sure its grounded well)
86 goes to 12V+ stud terminal on starter
30 goes to ignition switch signal

[quick.msp]

87 goes to starter 'S' signal
85 ground (make sure its grounded well)
86 goes to 12V+ stud terminal on starter
30 goes to ignition switch signal

so the way its shown on this write up is wrong?
https://grandmighty.github.io/grandmighty/2016/03/starter-booster-relay/

That explains why when I wired this up the car would not click or turn over......

I ended up removing the relay, and installing a new ignition switch and I have not had the issue since. If it does it again I will try again and wire up the relay as you have shown.

[digitalsolo]

driftnfb is incorrect.  It should be as follows, which seems to match the link you shared:

85 ground (make sure its grounded well)
86 goes to ignition switch signal (what used to go to the starter solenoid input/control lug)
30 goes to BAT+ (at starter or wherever)
87 goes to starter solenoid input/control lug