[cstavaru]

Hi,

Just wondering...can a failing fuel pump cause lower numbers on the dyno than a perfectly working one ? Did anyone do a dyno before replacing a HPFP and after ?

Thanks !

[FLA 335]

yes. i felt reduced power with my failing HPFP...

[ryan@ActiveAutowerke]

Failing pump failing power. Without a good fuel pump there is no way for the N54 to get enough fuel to produce the power of a N54 wit a new fuel pump. Don't worry this problem is very very i hate to say very common.

[canesr1]

Originally Posted by ryan@ActiveAutowerke

Failing pump failing power. Without a good fuel pump there is no way for the N54 to get enough fuel to produce the power of a N54 wit a new fuel pump. Don't worry this problem is very very i hate to say very common.

Does BMW have a new fuel pump out yet that works? Or are they still replacing bad pumps with "newer" bad pumps?

[Bme30]

im gonna go with.......YES!

[5soko]

i have been getting long cranks from about 2K miles and brought the car in for that reason at 3K miles.

Been feeling ever since i been getting long cranks the car has been down on power and i dont even get CEL or SES or limp modes. Threw 2AAF and 2FBF codes.

Got my car and DME software updated the power feels like it is back now, i will see how long that lasts until the HPFP 100% fails, but def power is not all there prior!

I can tell you this for sure, I ALWAYS insert my fob and press the start/stop button without pressing the brake to always prime the cars Pumps, and i always here a click followed by another click.. It happens on every 335i, when my car was long cranking i was not getting these two clicks
With the new software as mentioned before, when i open the car or the door in the morning i get a whinning sound now and when i insert the fob for and press the start/stop button without holding the brake, i am getting the click followed by click sound and no long cranks.

[cstavaru]

I wonder if this may explain my loss of power on the dyno: 297whp with good pump, 252whp when I tested a few months ago...

[marconi118]

The latest N54/N55 replacement HPFP is a re-manufactured HPFP under P.N. 1351-7-613-933. The 943 HPFP is no longer avilable thru the BMW parts system in the U.S. The 933 re-man HPFP is all that is available

Is the 933 better than the 943?

[cstavaru]

Originally Posted by TrackRat

If the AFR is correct, it's not the HPFP.

Well, if the HPFP pumps less fuel, I believe the ECU closes the throttle such that less air enters the engine, leading to less power but the same AFR ? Just my guess...

[cstavaru]

Originally Posted by marconi118

The latest N54/N55 replacement HPFP is a re-manufactured HPFP under P.N. 1351-7-613-933. The 943 HPFP is no longer avilable thru the BMW parts system in the U.S. The 933 re-man HPFP is all that is available

Is the 933 better than the 943?

From what I read, the 933 is a rebuilt HPFP but hopefully a strong one because I will receive one next week

[cstavaru]

Originally Posted by TrackRat

Nope. The throttle does not open or closed based on the AFR, only throttle position.

Maybe on carburetor and no-ECU cars The N54 opens/closes the throttle without driver intervention on many occasions. Look at all the throttle closure threads related to Procede/JB3 tuning. The tuners have a hard time preventing throttle closure occurring because the ECU tries to protect itself from certain dangerous situations.