whats up with my car?

[alexander525]

i have a 91 525i with the m50 engine. anyway when i accelerate my car expeirences a bog in the rpm at around 2500rpm. to describe it, it would be like my car hit a big patch of glue for a split second than realsed. it seems to only do this when the tank is low. it goes away when its full. or it seems less noticiable. i was thinking maybe it had to do with tank pressure but it does this in the exact same spot every single time.

[Sam-Son]

Probably the car is tilted and the car gets momentarily starved for fuel, Just a guess though

[bmwrp8]

check your fuel pump , relay , fuel pressure regulator and injectors. try changing your fuel filter also.

[markus]

you might also have a bad ignition coil too.

[Dr. evil]

hhhmmmm.... does engine temp ever make a diffrence??

my car does this when it's cold.

[bsell]

i have a 91 525i with the m50 engine. anyway when i accelerate my car expeirences a bog in the rpm at around 2500rpm. to describe it, it would be like my car hit a big patch of glue for a split second than realsed. it seems to only do this when the tank is low. it goes away when its full. or it seems less noticiable. i was thinking maybe it had to do with tank pressure but it does this in the exact same spot every single time.

Since you only experience this bog when the gas tank is low, I would say the fuel pump or pre-pump (if it has one) is weak. You should get similar weakness at the top of the rev range with an low tank also.

I assume the car runs fine otherwise? No other driveability problems?