New fuel pump installed...boy is it loud!!!

Craig D. Niederst niederst at
Wed Aug 7 22:32:14 EDT 2002

I just finished installing the new Bosch fuel pump into my '92 100S. The
3214 tool did the trick in getting the pump out. I cleaned up the screen on
the assembly, and cleaned up as much crap as I could from the inside of the
plastic housing in the tank. Got the new pump installed, reconnected all
hoses and electrical connections, and filled the tank with ~4 gallons of
gas. Reconnected the battery, turned on the ignition to hear the fuel pump
engage quietly (fuel gauge read a tad under 1/4 tank), and after a bit of
cranking, she fired right up. After verifying that nothing was leaking, I
headed to the nearest gas station to fill the tank the rest of the way up.
On the way up a steep hill, the car began to sputter badly, to the point I
had to pull off the road. I shut the car off, and it refired just fine. I
got to the gas station, filled the tank up, and when I tried to restart the
car, it started, but sputtered for about 5 seconds. I drove the car home
with no problems, but in the driveway, I could hear the fuel pump buzzing
very loudly. Upon crawling under the car, the buzzing was incredibly loud
and inconsistent (would buzz with pulses of louder buzzing). My old fuel
pump (also a Bosch unit, original to the car) never made a buzzing sound
like this, and was generally very quiet. When I start the car, the pump runs
quiet for about 30 seconds, and then the buzzing begins. The tank did have
some crud in the bottom of it, but nothing that could get through the
screen. I did not change the fuel filter (I did it about a year ago @ 90k,
has 99k on it now), but was planning on doing it when I finished the first
tank of gas after the pump change. With the pump sounding as it does, it
sounds like it is going to fail again real soon. Any ideas on what happened?
Bad fuel pump out of the box (it was made in the Czech Republic if that

'92 100S (99k)
'86 CGT (214k)

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