View Full Version : Help understanding Fuel Pressure whats correct?

11-17-2008, 06:34 PM
E34 1992 535i M30

Ok so I hooked up a pressure gauge to my fuel line today.

I got with vacum line looked up to FPR...
39 PSI @ idle

I got with vacum line disconnected from idle...
Approx. 53 PSI @ idle

With vacum line hooked up and car in park, I give it gas/rev it up and it goes up to
53 PSI holds till I let off gas and goes back down to 39 PSI

So can someone tell me if this seems wrong. I did some research I thought with more vacum applied, such as when I rev the motor or the throttle opens, the PSI should drop because of increased vacum to the FPR. Can someone help me understand this as I have already order a new Fuel Pressure Regulator...