In tank pump gone bad?

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Al Canuck
Posts: 658
Joined: Feb 12, 2006

Post by Al Canuck »

Hey Guys,

I'm much too lazy to actually test the pump right, and a bit pressed for time at the moment, so I'll ask for some opinions first.

85 535i. Runs like a scalded cat when it is still cool, and when the tank is over 1/2 full. If it gets under 1/2, or has been running for an extended period of time, it starts to feel very sluggish, and kind of surges under load. Feels way down on power. If you really get in it, it will sometimes fall flat on it's face, and choke. Let off a bit, it comes back. Once it gets under 1/4 tank, it gets REALLY bad.

Classic symptoms of a bad in tank pump, I say. Everyone concur?

Al
Guest

Post by Guest »

interesting.. just this afternoon my car started to surge really bad and when i would push the gas the car would jerk around like it was dying... i drove it to the shop and they told me i need a new in tank fuel pump, so i think that will fix my problem, and also get rid of that annoying ass BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ... steve haygood has em cheap.. gonna order one from him real soon.
pdx 528e
Posts: 3034
Joined: Feb 12, 2006
Location: Idaho Falls, ID

Post by pdx 528e »

[QUOTE="88 535is south florida"]interesting.. just this afternoon my car started to surge really bad and when i would push the gas the car would jerk around like it was dying... i drove it to the shop and they told me i need a new in tank fuel pump, so i think that will fix my problem, and also get rid of that annoying ass BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ... steve haygood has em cheap.. gonna order one from him real soon.[/QUOTE]

Did you ever find out if your throttle cable was part of the problem, or was the lack of throttle reponse due to the in tank transfer pump?
Guest

Post by Guest »

yea i got the throttle thing fixed, i believe it was the throttle body? it was a hunk of metal that had this spring type deal on it that turned flipped the metal thing in and out of the hole..yea i dont really know what i'm talking about but thats what it looked like.... the cable just broke away from that..
pdx 528e
Posts: 3034
Joined: Feb 12, 2006
Location: Idaho Falls, ID

Post by pdx 528e »

[QUOTE="Al Canuck"]Hey Guys,

I'm much too lazy to actually test the pump right, and a bit pressed for time at the moment, so I'll ask for some opinions first.

85 535i. Runs like a scalded cat when it is still cool, and when the tank is over 1/2 full. If it gets under 1/2, or has been running for an extended period of time, it starts to feel very sluggish, and kind of surges under load. Feels way down on power. If you really get in it, it will sometimes fall flat on it's face, and choke. Let off a bit, it comes back. Once it gets under 1/4 tank, it gets REALLY bad.

Classic symptoms of a bad in tank pump, I say. Everyone concur?

Al[/QUOTE]

I am not sure if those symptoms are enough to isolate the pump, but it would definitely be worth checking out! My sisters 528e has the same symptoms after a long drive, but it does not seem to be dependent on the tank fill level. Its been in the shop multiple times with no success, but since I'm sure no ones checked the pump, I think this could be part of her problem as well.
Guest

Post by Guest »

oh BTW whats the labor like changing the in tank pump?
pdx 528e
Posts: 3034
Joined: Feb 12, 2006
Location: Idaho Falls, ID

Post by pdx 528e »

[QUOTE="88 535is south florida"]oh BTW whats the labor like changing the in tank pump?[/QUOTE]

The Bentley covers this pretty well, it shouldnt be too hard considering you access it from the trunk floor by pulling out the trunk carpet/liner. Bentley suggests draining the tank.
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