I had a bad experience with a CSR electric water pump on my Z28. The pump had an internal short, which lead to a catastrophic failure shortly after being powered up. Unfortunately it created some collateral damage before the inline fuse link it was equipped with blew. From that event on, I have battled a major voltage problem with the car. At idle, the car barely holds 10volts. When you increase the idle speed above 1.5k I can read 13.8V through the ECM. The pump was tied to an ignition source in the chassis fuse block mounted on the driver side fender well. Some of the wires feeding the fuse block leading from the B+ source on the passenger fend well showed unique heat signatures and some of the wire had become very stiff. I pulled a new umbilical from a donor car this weekend, and look to replace mine with this one over the winter... I'm wondering if the BCM may be damaged too.... I assume the issue at this point had / has to be in line with items tied into the chassis fuse block.

After installing a Meziere pump, I spent the summer chasing this voltage issue replacing (using the GM wiring schematic) the ECM, ECM Grounding wires, Chassis Ground wires, all the charge wiring, put a power master 220A alternator in w/ a smaller March pulley, pulled the fuel injection wiring harness testing it, installed a new battery and scratched my head A LOT!!

The fuel pump and fans still kick on as they should... as do all the other electronics, but what's interesting is, when the car gets warm, the voltage issue seems to get worse stabilizing around 8 - 10v.... and unless you hold the throttle slightly, it'll die.

Another interesting feature I now have is, destroying ECM's on the dyno during a data flash..... you can flash the car all day when the car is cold though!!! TunerCATS will bump the fan's on and off & the fuel pump on & off during a flash.... Wondering if it's possible for one of them to have been damaged, but still functional at an increasing impedance level when the car is hot pulling a ton of current dropping voltage?? Just trying to find some common denominators here before I tear the car completely apart to the chassis - I'm looking for any idea's you may have on this one....

Bums me out to have a fresh 383 stroker ready to roll in a car I can't drive yet.

 

Resurrecting an old post – after spending the better part of a week tearing my car down, I believe the source of my problems have been found. The main ignition feed located on top of the steering column is smoked. Once I pulled the harness from my car, the Red and Orange feed pins, plus the connector all displayed severe heat discoloration and signs of arcing. Also found the factory heat shield had been rubbed through exposing wiring at a tight bend underneath the break booster. I have a clean low mileage factory donor harness and a new ignition switch to install this week. It’s likely these items are the culprits of my voltage and data flashing problems. Will post again once I have the new harness and switch installed.