Hey all. I have a 85 740 turbo. Cant seem to get power back to the in tank fuel pump. The gauge works but pump has no power I took pump out and tested it by jumping it to battery and it works and pumps( after replacing the flexible fuel line on pump had a split in it) What makes the pump turn on? Will the engine run without it turning on?. Because it does run! and has fuel pressure on injector line at engine. Mabey its lower voltage that my test light isnt picking up the power? If its a relay or something can i run a hot wire off ignition switch back to it so it constantly runs?
Thanks for reading and tx for replies!!

 

Haynes Manual shows a roundish fuel pump relay on drivers side under the dash extreme upper left. My 86 240 dl wagon in tank pump went while travelling and this forced the external pump to overwork and fail. The aftermarket in tank pump was much louder than the original though, and the constant whine tells me the pump runs all the time when the engine is on. Don't know how hotwiring it would affect the whole system though. Cheers.