88 Volvo 765 tic Removing Rear Floor Panels

lummert · Post by **lummert** » 16 Mar 2008, 09:53

I tried to remove the rear floor panel to get to the fuel gauge sending unit. I removed the three nuts and raised the panel and pulled forward and the panel would not move. Does the cover over the spare tire come out with the panel over the fuel sending unit?

Any help would be greatly appreciated.

Post by **billofdurham** » 16 Mar 2008, 12:51

The floor panel should come out by taking out the three bolts and pulling forwards and upwards.

Removing the cover over the spare should not be necessary.

Bill.

lummert · Post by **lummert** » 16 Mar 2008, 16:53

Today I removed the panel. It was stuck down with body sealer. All I found under the metal panel was a plastic ring for the sending unit and the fuel lines and three wires. I found the connector for the pump/sending unit in the left rear storage compartment. I tested for resistance at the wires for sending unit and got 170 ohms. That is what it should be for an empty tank but the tank was full.

Thanks for the reply.

Post by **billofdurham** » 17 Mar 2008, 12:10

New unit needed?

Thanks for the update.

Bill.

lummert · Post by **lummert** » 17 Mar 2008, 19:48

Bill,

My haynes manual states that the fuel sending unit should register 68 ohms with 3/4 tank. It also states that if you put a 68 ohm resistor across the wires to the gauge that the gauge should register 3/4 tank.

Thanks for the reply.

Post by **billofdurham** » 18 Mar 2008, 12:44

That is correct but you are talking about tests on two different things.

My info, not Haynes, shows:
Empty tank - resistance 296 ohms.
Quarter tank - resistance 196 ohms.
Half tank - resistance 98 ohms.
Three quarter tank - resistance 68 ohms.
Full tank - resistance 36 ohms.

If you are not getting these readings then, in all probability, the unit is defective.

The test with the 68 ohm resistor is intended to test the fuel gauge not the sender unit. Usually the gauge does not fail but it can stop working, along with the temp gauge if the voltage stabiliser on the instrument panel printed circuit board is faulty.

Bill.

lummert · Post by **lummert** » 18 Mar 2008, 18:42

OK,

I know that is two different tests. I was just stating that you can test the gauge with a 68 ohm resistor. I did not remove the sending unit from the tank I checked the resistance at the wires from the sending unit with a known full tank. Unless my multitester has a low battery I need a new sending unit.

Thanks for the reply, the Haynes manual has the same values for the resistance but it is listed for the float at certain positions.