Is erratic fuel pressure Normal?

[redstu]

I checked the fuel pressure on my e28 528i the other day. I would have expected to see about 35 to 40 psi , which in fact it is but its very erratic. Take a look at the video below.

Is it perhaps blocked injectors ? or is this normal?

thanks

http://www.youtube.com/watch?v=hVacWaQTtd4

[phelix]

I would suspect the pump or the regulator itself as the bouncing doesn't change as the revs climb (when the injectors cycle more rapidly). What does the fuel pressure do when you jumper the pump at the relay board with the engine off?

[GreenV8S]

Can't see how the gauge is connected but obviously it's an undamped gauge which is why it is all over the place. The fuel pressure fluctuates very quickly, far too quick for the gauge to respond, but what you're seeing is probably resonance between the fuel pressure changes and the gauge. Better gauges are liquid damped to avoid this.