I've searched but think I have al my bases covered so I'm looking for other possible electrical issues I can deal with...

Battery shows normal voltage (a little over 12v with the car off) but when I crank it with my starter button it drops to 8v!

All the engine compartment wiring is "custom" and for the most part I left the interior and dash wiring alone (except for removing the ECM).




Battery is relocated to the rear.
I am running a 1/0 welding wire from the battery to my battery cutoff switch.
1/0 welding wire from the batt cutoff switch to the starter.
The alternator charging lead is lengthened and ran to the "switched" side of the cutoff switch (but kept the stock fusible links and fuse tied in with it).

I have my battery grounded to the frame (1/0 welding wire), engine grounded to the frame (4ga ground strap), and battery grounded directly to the engine (4ga wire).


What other wiring could cause this? I have not started the car due to a fresh rebuild, the battery is a 4 year old Optima pulled from my Corvette but I cannot rule anything out...

 

Well, I charged the Optima but still am having some gremlins.

I guess I need a mini-starter and a new battery for starters and then I need to go from there.

I am thinking a need to revamp my alternator charging wire setup and find out why my DVM goes crazy inside the engine bay.

 

I'm pretty sure I have double checked them. The battery to frame, engine to frame, and batt to engine grounds are all A+. I have removed the pass side harness to the ECM so only have another ground to the drivers head that runs to the drivers side bulkhead. If I'm missing anything I wouldn't know where to look.


Seriously though, whenever I place the DVM over the engine bay it starts flickering like crazy. It will flicker any number (say 19.2 volts for a split second the 2.3 etc. maybe a tenth of a second between flickers). This only happens when the engine is running so it tells me it has to be from the alt creating some electric field in the air.

 

Yea this sucks.



Still need advise on what would be going on here. Buying a new battery and high-torque starter to hopefully fix the issue but I need ideas.

 

Much more likely it's EMI from the ignition, not the alternator.

 

Thanks guys. I just spoke with a friend who oens a business rebuilding alternators and starters (where I got the current alt and starter from) and he thinks it would be ignition related as well.


Is there anything I can do to combat this problem or is this inherent with the ignition I am running?


MSD Superconductor 8mm wires (cut to fit)
Procomp HEI large cap dizzy (50 volt coil)
NGK resistor plugs (same result with Autolite resistors as well)


Formerly small cap TPI setup. I have the pink wire supplying 12v to the dizzy and the white wire hooked up to the tach.
Would any of the other wires previously used on the ECM controlled ignition cause this?

 

Get a better DMM.

 

Picked up an analog meter today from Radio Shack. Decided to re-vamp all my wiring a little bit, however. With the new adequate starter, good battery, and new wiring this thing should scream.

 

Sounds like your starter is drawing to many amps causing your voltage drop. especially if you got higher compression. Wouldn't hurt to have a high torque starter anyway. good luck.

 

The battery wasn't in the best of shape so hopefully one better off will help. The battery cut off switch was rated at 20 continuous amps and 125 surge amps so that was a huge bottle neck (I can't believe it lasted this long!!!), and the stock style starter was a huge issue.

I received my new starter and went to put it on only to find out the mounting block hits the oil pan rails

Now I have to get around that somehow.

 

Little update...



Got a new Summit min-starter and decent sized working battery from a friend. Still receiving a voltage drop down to around 8 volts at the solenoid when cranking.

Also, showing only 12.5 volts with the car running. Alt bench tested fine, battery bench tested fine, both wires going into pigtail showing voltage.

I'm stumped.