erratic fuel gauge - not level sensor - 2004 XC70 Topic is solved

[altalake]

Shortly after last fill-up my fuel gauge started to show much less fuel than was actually in the tank.
No codes. Battery voltage OK. Assuming this to be the level sensor, I installed a new one and, as I discovered, there was lots (too much) fuel in the tank. New sensor and fuel gauge did not improve. Not worse but not better.
Disconnected electrical connectors and cleaned with DeOxit. No change.
Did DIM test with VIDA and everything, included fuel gauge, responded. Doesn't appear to be a DIM issue as described by Xemodex.
Car has 196,000km on it and has had very few electrical issues except, occasionally (and rarely) with headlights and turning it off and on always fixes that.
Any good ideas as to what this could be?

[scot850]

Did you check both level sensor for operation? The AWD cars have 2 level sensors and they average the levels of both sides of the fuel tank.

Neil.

[altalake]

This makes total sense and explains everything. Thanks for that. Not the cheapest solution but is something I can do myself, at least - but not until there is a whole lot less fuel in the tank.

[scot850]

Good Luck!

Neil.

[altalake]

Would anybody know which Bosch fuel pump is the correct one for this car? Apparently '04 could have been a year when they changed them. FCP Euro shows both p/n 67737 and 69958 for this car. Some sites show 67737 for '03, '04 and 69958 for '05, '06. Just to make it more confusing, some sites show the Volvo p/n 30761742 cross for both of these Bosch numbers.
Plastic tank. VIN YV1SZ59H741153747

[Georgeandkira]

My experience is positive over several small orders.

This could be where you got your 30761742.
https://www.tascaparts.com/v-2004-volvo ... components

This one does mention the plastic tank. Call them as they're helpful.
https://www.fcpeuro.com/products/volvo- ... 82980137kt

And last but not least....
https://www.rockauto.com/en/catalog/vol ... mbly,10147

[DavidE7]

There are two different electrical connector options for the right/passenger side main fuel module on the plastic fuel tanks. It is worth verifying the correct connector before ordering the replacement fuel module. The fuel height sensors are relatively easy to service without replacing the entire module if you can find a replacement part. The electrical connector for the height sensor plugs into the bottom of the flange and there are two plastic clips holding the height sensor into the side of the reservoir bucket for the right side and two very similar clips for the sensor on the sprung jet pump bracket on the left/driver side of the tank.

This post has more details for a bad left fuel height sensor i replaced a months ago: viewtopic.php?p=680266#p680266

I replaced a friend's 2007 V70 right module fuel height sensor a year or two ago because it was burnt and was showing 1/4 tank of fuel in an empty tank. It was very similar in design to the left sensor (sensors are not interchangeable left and right because of different metal arms, floats, and ceramic cards). You will be looking for a burnt or worn spot on the ceramic resistor card. A multimeter can be used to measure the output on the two wires while slowly moving the float arm through the full-empty-full arc. The resistance measurement should gradually change as the arm moves.

[DavidE7]

Also - be aware there was a service recall for leaking right fuel module flanges:
https://static.nhtsa.gov/odi/rcl/2009/R ... 3-8017.pdf
and
viewtopic.php?p=665649#p665649

The recall replacement fuel module flange is a yellow color. The original fuel module flange is a white color.

FCP Euro confirmed the correct part number based on my 2004 XC7's VIN. After the replacement I saw that the FCP Euro pictures showed enough of the electrical connectors on the top of the flange to see the difference between the different part numbers. I believe all the Original Equipment fuel module part numbers were from Bosch.