SICAMG

Just wondering if anyone has used the Kenny Bell boost a pump on an E55. I had it on an Aeromotive system on my road race car and it worked really well.
I heard that our power feed is pulse width ?? Is this true?
Also are both pumps running all the time or just one until supercharger kicks on?

sjc246

Not that I have ever heard of. Do you think you are reaching the limits of your stock pumps?

No. It's controlled by one or two mechanical relays. Standard mechanical relays cannot be pulse width modulated: the pumps run full speed all the time. Newer MB pumps are variable speed, but I believe they are actually run on multiple phase a/c power (created by the fuel pump control unit), so the speed is controlled by the frequency of the alternating current, not really pwm.

That depends on your production date or model year (I'm not sure which). Early cars used one relay for both pumps and they both run all the time (until the relay and sockets melt). Later cars had two separate relays. One pump runs all the time and the other is controlled to run only when needed (I don't remember the exact criteria, but I believe it was switched based on rpm and engine load). I believe that most if not all 2006 cars have the independently controlled pumps and at least some of the 2005 pumps ran all the time. I'm not sure if the change was sometime during the 2005 model year or if it started for the 2006 model year.

SICAMG

Not reaching the limits yet but just doing some research and thinking outside the box
. Dialing in a solid voltage especially on a hot night running when voltage drops a little...ac, head lights and what not, pumps don't see the voltage that it was when cold. So pressure will drop and this I have seen.
When the snow stops!!!!.... I will throw some volt meters at the pump wires and see what it's doing with one or both pumps. Was just looking for a heads up on info...thanks !!