V70R fuel return and pump

Pussi · Post by **Pussi** » 20 May 2019, 04:56

Hi, I have a 2004 V70R. The car blows fuel pump fuse almost immediately after turning the key. I have narrowed down the issue and the culprit seems to be (what I am guessing to be) the fuel return pump. The wiring for the second pump (must be for return line?) goes through the tank from the drivers side where the level gauge is located. If I unplug the wire from the fuel gauge assembly, the car runs just fine. Is it ok to run the car without power to the return pump or does this have any immediate or long term harm to the fuel system?

Only asking because I really need the car before I can get my hands on a new fuel pump assembly.

Thank you in advance.

Pussi · Post by **Pussi** » 20 May 2019, 05:02

Answering my own question. It came to my mind that these cars have a saddle shaped fuel tank. Is the purpose of the other pump solely the pumping fuel from the other side of the tank to the side in which the main pump resides? If this is the case, then keeping fuel levels above, say 1/4 tank would render this "return pump" pretty much useless?

Post by **oragex** » 21 May 2019, 10:16

I would guess so. Try keeping the tank fulled to at least 1/2 (since that fuel gauge is already a little inaccurate).

I would guess, a previous owner messed with the fuel pump assembly at some point, so if removing it from there, look careful at all wiring. Also remember the trick to pass a cable and capture the hoses inside the tank not to loose them inside (google up).

I have a video with the sender unit from an S60 www.youtube.com/watch?v=-egNDgTdUYE

On these cars, the fuel pump is rarely the problem, most of the times we deal with the pump regulator module PEM and sometimes also with the FPS sensor.

EngineeringBloke · Post by **EngineeringBloke** » 21 May 2019, 18:13

On these cars, the fuel pump is rarely the problem, most of the times we deal with the pump regulator module FPS and sometimes also with the FPS sensor.

Should be: Pump Electronic regulator Module PEM

Module was under car and exposed, so would rust. Volvo made new cars with it in the trunk, near the spare wheel, and relocated it for prior owners.

Symptom is PEM sounds like a box of sand when shaken (unmounted). The internal rust is conductive and affects the PEM function.