My 740 has a regina system . The intank fuel pump has a positive and negative terminal to which upon fuel pump change incoming leads must be soldered to these terminals. last month the car shut down with me and and a fuel pump change was done. Fixed ...so I thought!!! Today Im having the same problem! To let you know what the history is...30000 miles ago the fuel pump was replaced.
I have not had a problem since. After this new pump..from volvo...was installed i renewed the fuel pump relay as well. The 25amp fuse No.1 on the panel tested ok with a continuity check also. Now in trying to diagnose ..THe old pump... which I insisted in getting back ...I connected to a 12v battery to see if it would operate and it did!!! Now how could that be ? I thought it was defected! Now to eliminate the source of power to the pump I have decided to tap into the pump at the connector located in the trunk. This connecter has four wires..two large and two small. I figure the small ones are for the fuel quantiy sending gauge whereas the larger ones are the power wires the black being the negative and the pink being the positive. Now is it at allpossible that I could connect an external battery here to see whether the pump works ?
IS the voltage to the pump under normal operation reduced to less tha n 12v?
any suggestions? PS the crank sensor is also new..and I dont here the normal hissing sound when i turn thr ignition key on initislly.