There has been a lot of discussion about the fuel pressure made by the lift pump and its effect on starting, fuel economy and even bearing failure. So I decided to install a fuel pressure gauge that I can monitor while I drive.

Initial reports show that at idle I have ~0.75bar right in the middle of the manuals 0.6-0.8bar min. The interesting thing is that I stretched my spring out last summer ~ 17k miles ago. At that time the pressure at idle was closer to 0.9bar.

If I rev. the engine up to ~3000rpm I get 1 bar above the 0.8bar min.

Now here is the interesting thing. When I go for a spirited drive the fuel pressure drops to 0.75bar at higher rpm and full throttle. I wonder if the lift pump can keep up with demand on the highly modified engines.

I'll update as times goes on.

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1998 Mercedes E300TD

1983 Mercedes 240D Turbo, 131bar injectors, Cosworth intercooler and 63' Ford Falcon radiator, Ardic Parking heater, Headlight wipers, Best 38.6mpg.

1973 Saab 96 Rally Car, 1.8l V4 with all the race bits