(1) have a helper in DR seat (2) you underneath & pull L connector off of the sender threaded stud (3) have helper turn ign key on (4) gauge should stay on E (actually left of E a bit) (4) you ground the blue wire L connector either all the way up to the batt neg post (best) or at least to a KNOWN frame/body sheetmetal ground & have the helper tell you if the needle swings rapidly toward F & have him holler when it gets close to F so you can pull the connector & stop the gauge before it pegs. this confirms that all is good from the L connector forward & the problem is the sender or its ground path there at the tank all the way back to the battery.
