QuestionMy 89 735i is not getting fuel. I disconnected the fuel line to the fuel
pressure pump and turned the key to see if fuel will come out of the line (i'm
being careful to have the fuel line go into a container.) When I turn the
ignition on I can hear the fuel pump activating 4-5 times and then stops. No
fuel comes out into the container. Previous to this problem, my car was
running rough and was diagnosed as a bad o2 sensor. I replaced the sensor
(oem) and didn't have it plugged in all the way before I tried to start the car.
That's when I disovered it wouldn't start. I plugged in the sensor correctly
and still it wouldn't start. The car turns over, but isn't getting gas.
AnswerHello Annie,
The O2 sensor will not prevent the car from starting, but it can make it run badly.It only affects the fuel to air ratio and not the actual fuel supply.
The logical way to diagnose your fuel supply problem is to check for fuel at the fuel pump's outlet or at least before the fuel filter, then after the fuel filter, then before the fuel regulator. So you were right in checking after the pump except that you did not find any fuel at its outlet.Thus, since you hear the pump activating for a few seconds at key on-- either there is no fuel in the tank,
or the suction of the pump is clogged, or the electric motor of the pump turns but the pump itself is defective.
Removing the pump does not require a rocket scientist but it does require mechanical skills, tools, due care since gasoline is a very dangerous volatile fluid, and a lot of common sense. Any spark (electrically induced or otherwise)
can make your fuel tank a bomb. And you need good ventilation too.
Pls. note that the fuel pump only activates for a few seconds when you turn the key on, then the engine computer turns it off. You need to start the car or at least crank the motor for it to continually pump.
The world needs more lady do-it-yourselfers like you.
Just tell me if you need more info. Regards,
Tino
