I replaced the pump yesterday with GM Genuine, complete with their fancy blue GM tape -- I almost feel like I'm breaking the law opening the box!
Anyway, not much useful info because I didn't have time to dead head the new pump.
The existing pump was a Carter, so yeah, it's been done before. But judging by the amount of rusty dirt on top of the tank, it's been a long time.
I know it's not an accurate indicator of pump health, but when the pump primes it's virtually silent. The old Carter had a distinct whine. On initial start I thought I had somehow screwed up wiring the provided 4-flat replacement electrical connector, but no -- it's just really quiet
You had to attach that 4 wire plug that came with the new pump? If the old pump didn't already have that installed then its very old. GM updated the electrical connector design with that new plug due to the old design not being insulated enough and burning out/shorting the connections.
Also, I would advise you strongly remind the owner that its VERY important to not let the tank get below 25% before filling up. These pumps do not like heat at all and waiting for the gas needle to drop down to the red zone before filling up will prematurely wear out the pump due to it not being cooled properly with the surrounding gas. People forget that in-tank fuel pumps are "liquid cooled" by the gas and when that's not there, they heat up.
And yeah, the signature whine of the pump lets me know its working Apparently they have gotten much quieter over the years. Glad to hear you were able to get it done