2005 SL65, my PSE pump runs for just over 90 seconds whenever the car is started. After that, I rarely hear it turn on again, if at all.

Is this normal?

 

I would say it's a little excessive run time... don't remember mine to run that long... the only reason I see is that you have a leak somewhere, the pump is running until goes in safe mode so it wouldn't break down from working nonstop. And when you stop and start the car again it resets the system...

 

It’s my understanding that if there is a major leak, the pump will detect it and permanently stop trying to pressurize that circuit and the circuit will remain disabled until a reset is performed via SDS or the PSE fuse is taken out and then reinstalled.

If it was a minor leak, I would have expected to hear the pump keep kicking back on periodically while driving.

 

It should run no more than one or two seconds. I'm surprised yours is able to run as long as it does, as I would expect it to timeout for major leak detection long before 90 seconds.

 

maybe a faulty pump that just can't pressurize as fast but still gets the job done?

 

Ok so it’s not the PSE pump or the roof pump. What else in the trunk could be making a noise? The noise also happens when the engine is not running (but it lasts for a shorter time)

I think there is an aftermarket amp back there somewhere, wonder if it has a really loud fan or something?!