Thanks for replies. I agree I should check that the pump is capable of delivering enough pressure (this reminds of my s-l-o-w wipers - bad motor). I get confused though with fuel pressure low/high etc. When the engine is cold, you want to enrich the mixture. So, for a given position of the air metering plate, you want more fuel into the engine, right? That means the fuel pressure must be higher, no? My understanding of the control pressure regulator (or warm-up regulator) is that it increases the restriction in the return line to the tank when the engine is cold, thus increasing fuel pressure. As the engine warms up, the restriction through the regulator decreases, a larger portion of the return fuel passes through the regulator and fuel pressure drops. I'll do some more troubleshooting on the pump first, though.

Thanks,
Kåre