Hi everyone, so I've been having a problem with my 1984 Toyota Van's fuel gauge not working correctly. I've replaced the fuel sending unit only to have it still read incorrectly. I've gotten a 3rd unit and still nothing, I thought it was strange because this one looked a lot better than the others (I pulled it from a 1988 van at the pick your part), so I decided to test it out on another Toyota Van that I know displays fuel level correctly. I plugged it in to that van/s harness and the sending unit works fine. Whenever I disconnect the fuel gauge on the van in question the gauge goes to empty so that gauge should be working fine. So this leaves me to believe that it could be a ground issue?
So the problem now is I can't find the ground, wiring diagram in repair manual says that it's located "in fender apron near manifold". Please excuse my ignorance but I'm not sure where that even is. So if someone could point me in the right direction I would really appreciate it! Also this is my first post here!!