1991 740 Only one fuel pump

Duhuhude · Post by **Duhuhude** » 24 Jul 2014, 09:27

Hello all,

I recently diagnosed and replaced a bad fuel pressure regulator on my 1991 740 wagon (b230f), and now I am trying to change the fuel filter. I know that I am supposed to remove the fuel pump relay, then turn on the engine to empty the lines, then disconnect the filter. When I removed the fuel pump relay, the car did not start, and when I looked under the car, there was no fuel pump, just the filter with one line coming from the tank, the other going to the fuel rail. Is this a problem for changing the filter? Why does my car have only an in-tank fuel pump?

Thanks in advance for your help!

lummert · Post by **lummert** » 24 Jul 2014, 10:59

Maybe it's a Regina car. Bosch LH cars have two pumps. Regina cars only have an in-tank pump.

93Regina · Post by **93Regina** » 24 Jul 2014, 11:36

Duhuhude wrote:...then turn on the engine to empty the lines, then disconnect the filter

Wear goggles and just remove fuel filter. I clean threads/pipe before removing, and I have a rag to soak up fuel.

Rex-I/Regina used a single fuel pump in-tank; access via trunk on 4-door models.

There should be a black box on engine firewall, and another box around passenger kick-panel area.

Duhuhude · Post by **Duhuhude** » 25 Jul 2014, 03:39

It is indeed a Regina system, I didn't know that Regina cars were only supposed to have one pump.

Thanks for your help, lummert and 93Regina!

93Regina · Post by **93Regina** » 25 Jul 2014, 05:30

Duhuhude wrote:It is indeed a Regina system

Vehicle might also have a lockup torque converter (AW70L or AW71L); on mine, the torque converter lock-up is around 45-mph (72 Km/hr).

Duhuhude · Post by **Duhuhude** » 28 Jul 2014, 04:09

I'm pretty sure it's a AW70L with the lockup torque converter. How do I verify this?

93Regina · Post by **93Regina** » 28 Jul 2014, 07:09

Duhuhude wrote:How do I verify this?

The transmission is identified from the product plate on the left-hand side of the unit.