Extreme fuel pump whine

[zesinlijn]

Hello!

Just went for a ride in the 325i and suddenly the fuel pump started whining very loud. (like this one https://www.youtube.com/watch?v=C1g7jf7HcjU)

car didnt stall but it did lose all power. I was able to get home at a slow speed with very little throttle input.

I turned of the car and checked the fuel pump connections.. plugged them back in and started up the car and the whine was gone. Pulled connector back off and plugged it in again and the whine returned. turned of the car and started it again and whine was gone again.

Just finished restoration of the car and only drove about 200 km. Fuel pump was brand new and Oem BMW, filter brand new. bit more then quarter tank of gass at the moment. (first full tank of gas since restoration)

could this be the other pump that transfers the fuel to the other side of the tank?
other possibilities?

sorry for grammar mistakes, i'm from belgium =)

tnx!

[dnguyen1963]

Yes, check the transfer pump first. Your high pressure pump might be fuel-starved.

[mpowerful]

That is prob a one pump system eh? Ie no transfer pump. Anywho check your fuel pressure. Could be a restriction in the line somewhere. The intake return path for the tanks has some narrowing orifices and they get clogged. Usually fuel pressure goes way up and strains the hell out of the pump.

[zesinlijn]

I have 2 pumps in the tank. the one on the passenger side is the main pump right? so the other one is the transfer pump? Mainpump was brandnew 200 km ago.

today i pulled out the main pump. noticed that there was enough fuel in the area where the pump sucks out the fuel.

The pump pickup filter was full of rust sediment and also on the bottom of the tank. cleaned off the filter and put it back in.

Possible that pump is broken by the rust and i'll prob going to need a new gasstank? :(

[dnguyen1963]

The pump inside the tank is the transfer low pressure pump. You will need to drop the tank, clean out the rust, and seal it...might not need a new tank yet. For short term solution, if you have a peristaltic pump, you can pump out the dirty gas with rust into a bucket (drop a big magnet in there to capture the rust). Pump the "clean" gas back into the tank, mix it up well, and repeat this step multiple times until you do not see any noticeable rust in the gas. This procedure can keep you going for a few years. Do not re-use the gas when you are done with this procedure. Put in fresh gas and add Heat gas treatment into the gas to keep water condensation to minimal.

[zesinlijn]

I only have one fuel pump.. no external fuel pump.. thing on driver side is a fuel level sensor

[KMOSES]

Check for restriction on the fuel return line (there should be less than 5 psi.). If there is a lot of restriction on the return line (say 20 psi.), that fuel pump will wine loudly. The later model E30s had a venturi in the gas tank metal return line on the drivers side that can clog with rust. The metal return line enters at the top, goes across the inside bottom drivers side, then up over the gastank hump and down to the base of the fuel pump. The venturi is at the bottom of the tank on the drivers side. As the return line fuel rushes through the pipe a low pressure area is created that pulls the gas from the drivers side into the pipe with the fuel going to the passanger side of the tank. If there is rust in the tank, it gets pulled in and blocks the pipe causing back pressure. When it does, the fuel rail pressure goes way up and the pump starts to wine.

[zesinlijn]

Tnx for this information!

Can i clean the inside of this tube with the tank still installed in the
Car?

[KMOSES]

I took a 3/16 OD flexible tube and inserted it into the metal fuel return line at the base of the fuel pump and shoved it as far as possible into the fuel return line. Then using a air nozzle and about 90 psi air I pressurized the line. I was able to get it unclogged and it worked well for about a month before getting clogged again. In the end I just replaced the gas tank to solve the problem. I think the inside of metal fuel return line had rusted along with the tank.