Hi,

I posted a question about my fuel gauge on my 94 940 wagon.

The gauge now works sporadically, so I am not sure it is the sending unit. And since it is $300 I am not willing to replace it until I know it is bad.

I pulled the access panel and found the wires coming from the prepump and sending unit. I assume the 4 wires are to the prepump and the 2 wires are from the sending unit. I found the connections inside the driver's side wheel well. The 2 wires run to a small rectanglular plastic black box. I cannot get it to open easily. BEFORE I pry it open, I would like to know: 1. What is it? and 2. Will I screw something up?

I also pulled the cluster and couldn't find anything loose there. Although I did not disassemble the cluster panel. I chickened out.

Thoughts??

Thanks

Tom

Regarding your '94 940 wagon's fuel level sensor. Diagnosis and repair is relatively simple. Requires 10mm socket wrench, Torx wrench #25, blade screw driver, volt ohm meter, and the usual assortment of curses.

[Unsolicited advertisement: the '94 940 wiring diagram is publication #TP 3904202, available from 800.25-Volvo for less than $30 US. *Every* Volvo shade tree mechanic should have the wiring diagram for their car -- Volvo wiring diagrams are superb. Superb! Also, buy the Pocket Data Booklet, #TP 0302207, about $25 US. This tiny book is worth its weight in gold: complete specs for '91-98 700, 900, 70, 90, and 850 models including torque settings, part numbers (Volvo and Bosch!), exploded suspension diagrams, and diagnostic trouble codes, and much more. OK, I'll get off my soap box now.]

You will find a 4-wire connector (called C93 in Volvo's wiring diagram, page 114-115) inside the left rear deck well. It is glued to a sealed box containing the connector to the speedometer sensor; don't open that box. The glue looks horrible but is pretty easy to remove: just yank the connector off and scrape off the excess.

Fuel level sensor wires are grey/white stripe (pin 2) and brown (pin 3). The fuel level sender is a variable-resistance device. If you have a good ohm meter and a siphon pump, check that the resistance changes as the fuel level changes. Or you can turn the sensor upside down. This is easier to do if the sensor is out of the car... ;-)

If the sensor's resistance changes with the fuel level, the problem is most likely in your wiring or gauge. The speedometer sensor is driven from the same controlled voltage as the fuel level sensor: if neither speedo and fuel level gauge work then check the fuse on the back of the combined instrument (gauge cluster). If the sensor's resistance is constant regardless of fuel level then you must replace the sensor.

Fuel sensor removal procedure:
Your directions for finding the access panel are correct.
The access panel is held on by 4 10mm bolts.
Remove bolts and the access panel to reveal all plumbing into/out of your gas tank. To remove the sensor, FIRST DRAIN ALL GAS from the tank and hoses. Be safe, OK? Volvo provides thoughtful assistance for this, including a nifty drain (resembles the tire air stems) just behind the fuel pump. Maybe someday domestic cars will be designed this thoughtfully.

Label and disconnect all hoses at the tank cap. Remove the large hose clamp which immobilizes the tank cap ring. To unscrew the tank cap ring, place the blade of a short screw driver against the convenient ridges on the ring and carefully strike the screw driver with your hand or rubber mallet. Drive the tank cap ring COUNTERCLOCKWISE a ridge at a time until you can completely unscrew the ring by hand. Remove the ring.

You can now pull the tank cap out. A sealing ring offers moderate resistance. Be careful not to nick the sealing ring or else you must buy a replacement from Volvo to prevent fuel leakage. The fuel level sensor and fuel pump are attached to the bottom of the tank cap. Getting the cap/sensor/pump assembly through the access panel can require contortions. Apply curse words liberally for symptomatic relief.

The fuel sensor wires are soldered in place. Make *DARN SURE* that no gas fumes remain before you start that soldering iron! Installation is the reverse of removal. Two warnings: the sensor must be vertical and you will have better luck if you put the sealing ring into the tank cap neck and then push the tank cap into the neck until it seats correctly. Replace and tighten all hoses. Refuel. Check for fuel leaks before closing the access panel. Apologize to spectators for cursing.

--
-- Bruce / '82 244 (298k miles!), '86 745, '87 760Ti, '94 854

Thanks!

That's a great description of how to check it out. I could have sworn the wires came from the tank. Oh well, it worked most of the way home tonight.


Tom

I have a 95 940 wagon...same problem....Ususally its the sender....as you know...no aftermarket sender and the volvo sender is very expensive even from Borton.....Im curious ..where did you find the access to the panel at the fuel tank.????? I cant find it....JOHN

Here's where and how I found it on mine:

1. Fold the back seats down.

2. Take off the three nuts holding the spring loaded panel--10 mm nut

3. Under the panel on the driver's side you should find an access plate.

4. Remove the access plate and bingo! The fuel pump cover.

I did NOT remove it. I don't know if you can pull the pump and sending unit (or are they the same?) out from that angle or not. But..it would be worth trying before removing drive shaft and dropping the tank. I traced the wires from the unit, out through the back of the wagon, into the wheel well where I found the small, flat black box with the sender(?) wires going in one side and coming out the other. Do you have any clue what that box is? I can't get it open and don't want to do something stooopid.

I am trying to rule out a simple connection issue before going the expensive route of replacing the $300 sending unit. Since the gauge works sporadically, I feel kinda OK monitoring the mileage and watching to see when it wakes up. At least until I get stuck someplace and SWITBO (she who is to be obeyed) rescues my sorry self.

Good Luck!

Tom

I have a 95 940 wagon...same problem....Ususally its the sender....as you know...no aftermarket sender and the volvo sender is very expensive even from Borton.....Im curious ..where did you find the access to the panel at the fuel tank.????? I cant find it....JOHN