2005 S60 fuel pump ground

[jgs18]

2005 volvo S60 2.4. 5 years ago car quit running took it to volvo they replaced the fuel pump. last year it stopped running again, I removed the back seat to look at the connections and noticed a wire coming out of the top of the fuel pump that was just laying there with electrical tape around the end, i removed it to re tape and when it touched the frame the pump started running? car would start and run, after running a few minutes I could disconnect that wire and car would run, sometimes I need it to ground to start the car sometimes not. ( i made a jumper wire out from under the seat with clamp to connect to frame when needed). then over time I needed to have it connected all the time or the car would not run. Next the fuel gauge stated only reading 3/4 (2/3) of a tank even when full, then check engine light came on indicating low fuel pressure though it ran and drove fine. 2 weeks ago it died again while driving. this time I took it to local mechanic who found that the ground I had connected heated up and disconnected at the fuel pump, added new connection on the wire end and reconnected it at the fuel pump and car will run. He can't find a good wiring diagram for the fuel pump system to trace what the original problem is, why the original internal ground does not work? is it the PEM i do live in PA, salty roads.?????

[abscate]

You can't troubleshoot electrical stuff without the wiring diagram. Period.

Doubly true when someone has hacked up the wiring in some unknown way.

The diagrams are on the web, but we don't host them here by arrangement with Volvo.