'87 325is fuel filter buzzing pulse, help!

[GUERONASTY]

So just picked up a new set of wheels. I took them off to respray them. When I finished and put wheels back on I went for a spin. When in first gear car started to bog same in second & third. The car revs and red lines fine when in neutral. I also noticed that the fuel filter on drivers side underneath the car is buzzing in a pluse. Any body have had the same problem??

[GUERONASTY]

...think it's gonna be the fuel filter because I checked fuel lines made sure did not pinch when I jacked up car & seems to be fine when I let it build fuel pressure until I give it to much gas

[UserError]

That's your fuel pressure pump. The fuel filter itself is in the engine bay, near the starter. Early E30s have two, one in tank, and one in-line. Pop the rear seat and see if unplugging the lift pump makes the problem any worse. If it doesn't, then the lift pump's shot. If it does, then the pressure pump's done. Note, however, that there's nothing saying that both pumps can't be bad at the same time.

[jlevie]

The buzzing sound is from the high pressure pump. It may be loud because it is having to work too hard (clogged filter, obstructed line, bad transfer pump). Or it could be that the pump is failing.

[jeffnhiscars]

We had a fuel line noise from in front of the rear wheel on the 87 325i and it turned out the in-tank transfer pump was dead. This caused the pressure pump to suck so hard to compensate that it caused cavitation in the fuel line (ie air from no air) . The car ran, but like crap since it was starving of fuel.

The fuel filter was there as well on our 87.

[GUERONASTY]

That's your fuel pressure pump. The fuel filter itself is in the engine bay, near the starter. Early E30s have two, one in tank, and one in-line. Pop the rear seat and see if unplugging the lift pump makes the problem any worse. If it doesn't, then the lift pump's shot. If it does, then the pressure pump's done. Note, however, that there's nothing saying that both pumps can't be bad at the same time.

Some cars have in engine bay others underneath the car.

...so I just replaced fuel filter and ran a bit better but still not like it should I think it is gonna be the fuel pump.
There's two plugs coming from gas tank one is for pump other for fuel gauge, right? Lol noob and trying to see if I can fix myself and learn.

[jlevie]

Your 87 has the 55L tank with a transfer pump in the right of the tank and a high pressure pump in front of the left rear wheel. The pump housing hold the level sensor, which gets one of the connectors. The other goes to the transfer pump.

[GUERONASTY]

Your 87 has the 55L tank with a transfer pump in the right of the tank and a high pressure pump in front of the left rear wheel. The pump housing hold the level sensor, which gets one of the connectors. The other goes to the transfer pump.

I'm thinking it's gonna be the high pressure pump because it's the closest to fuel filter making the noise. Anyway to find out what ones the bad one???

[jlevie]

The in-tank pump hardly ever gets noisy. They work (with a very slight buzz) or they don't work at all. If the transfer pump is working a noisy high pressure pump will be a clogged fuel filter, obstruction in the fuel lines or FPR, or a failing high pressure pump.

[jeffnhiscars]

You've had more than one suggestion that the noise at the filter is likely to be caused by a faulty in-tank transfer pump, which will make a working high pressure pump struggle, thus creating that noise.

Why dont you disconnect the transfer pump, THEN try to start the car (in that order so you do not create a spark at the tank) and see if anything changes.

[GUERONASTY]

You've had more than one suggestion that the noise at the filter is likely to be caused by a faulty in-tank transfer pump, which will make a working high pressure pump struggle, thus creating that noise.

Why dont you disconnect the transfer pump, THEN try to start the car (in that order so you do not create a spark at the tank) and see if anything changes.

Yeah was gonna try that tomorrow moring with results

[GUERONASTY]

I'm having trouble dropping new transfer pump in seems like it's tall is there a special way? I made sure it was the right one already and making sure pump matches slots on tank.

[jlevie]

You are trying to do with with the level sensor not installed in the pump housing, right? If you are and the pump isn't going all the way in, you don't have it oriented properly to engage the locking tabs or the bottom of the tank is bent upwards.

[GUERONASTY]

Figured it out gas tank has a GIANT dent from some one placing jack stand slipping and bending tank just enough to f*ck with transfer pump. Looks like gonna have to use a crowbar or a new tank

[dnguyen1963]

Use a round wooden stick with a rubber mallet to gently knock the bottom of the tank down.