I am trying to track down a buffering issue with the fuel gauge and where the signal might be buffered? This has been going on for a while and when I had to drop the tank to fix a fuel leak I thought it might at last be fixed. I installed the new assembly and is still the same as previous. The fuel gauge responds as the fuel moves within the tank with no buffering. This is a 2000 4dr Blazer with more than a few miles, and continues run fine.
Just a little history when I believe it all began..
Took to a transmission shop to check a transmission code for manual shift solenoid, and when I got it back, they had replaced the shifter cable (automatic on the column) because the connector to the transmission shift lever broke. BTW, Manual shift solenoid code was not fixed, but there were no symptoms that there was an issue with the tranny before or after either way..
The first indication that something was wrong when I picked it up was when I stopped at the stop sign the front ABS engaged at about 3 MPH.
Took it back and they replaced the ECM, I supplied the unit and he programmed and installed at no charge. Didn't help.
Put original back in, still the same.
I discovered that when I came to a hurried stop, the speedometer was still registering a few MPH and would take a second or two to register zero. This now made sense that ABS kicks in since the conflict between VSS, and speedometer didn't match causing the ABS to engage.. I disconnected ABS to keep from kicking in but am scratching my head as to what the connection could be between fuel gauge and speedometer could be. The transmission shop was no help, and I was left with a quirky issue.
A few years go by and I have now become determined to track this down and make it right. I swapped out the instrument cluster but that did not help. BTW, milage is indeed stored in the cluster on this gen. VSS is reading correct on my cheepo scanner, and just to be sure I replaced it anyway. I'm going for electrical issue, but don't know where to start. The fuel sender reference (purple) and orange black apparently are intact, since I see a fuel level. And the speedometer works, and is accurate, just a bit sluggish getting to zero.
So I'm reaching out for any ideas. I'm exploring ground connections and cleaning the ones up that I can find. Electricals are hard to find for anything beyond the fuel sender pump wiring which appear to go the the ECM plug C3.
Two other issues, likely unrelated, but want to mention. EVAP code, I'll be going to the back of truck and check out the purge solenoid... And the other issue is engine idle when cold start-up. On the idle, the RPM's start out a bit High as expected but as I drive the idle goes up enough to keep the truck moving at 45-50 MPH. The only way to get the idle down is to stop, but transmission into neutral or park and only then will the idle drop to the normal 650 RPM. I'm going to explore idle air control, expecting to be a separate issue, but can't rule out a commonality with all of the above.
Any ideas?
BTW those are the only two codes that are present, and what live data I can monitor is showing good feedback Data.

Thanks