Had a failure of the in-tank lift pump or pre-pump on my 1991 740T wagon. Was alerted to it by the main pump, under the driver's seat, making a racket that sounded like a vacuum cleaner sucking on a straw that was in a nearly empty glass of water. The main pump is less than a year/24,000 miles old.

Of course this symptom, a sudden increase in noise from the main pump, is well documented in the FAQ as being indicative of a lift pump failure. But, I like to verify and found it hard before, when the lift pump was working, to hear it from the filler neck or from the place where the sender/pump assembly goes into the tank.

Found out, by just checking, that my failed pump showed infinite resistance across the red and black wires at the connector at the driver's side rear of the car. This connector carries the fuel level signal for the gas gauge as well as the power for the in-tank lift pump. The new pump measured 175 ohms across the terminals. For those who have a hard time determining whether or not the in-tank pump is working, this might be useful. Be sure to check the resistance between the red and black wires on the side of the connector that goes to the pump, not the side that goes to the front of the car.
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Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)