1978 928 5 speed fuel pump delivery test.

Thanks. I've been looking for obvious, visual intake leaks and don't see any. My recently rebuilt warm up regulator had below accepted range control pressure readings = rich running condition. Have sent faulty WUR back to IMC for new rebuild. I imagine I have to have car running to do vacuum test?

Yes. Have you tried spraying starting fluid around the manifold and vacuum lines to spot leaks? I don't know if you're familiar with the Nichols 928 tips page, but someone once posted a tip for creating manifold pressure without having to run the vehicle by forcing air through the AFM and then listening for air leaks. Though, I have not done that, it sounds like it would be very effective as the noise from the vehicle running would not be a distraction.

Here's the link from Greg's site... www.nichols.nu/tip367.htm

I have sprayed with no results. I have a '78 928 with K basic CIS--no afm. but I may be able to put vacuum pump on intake plenum and look for reduction in vacuum. but I am quite sure WUR is the problem.

My limited knowledge of K-jet systems tells me that your suspicion is probably right. The WUR doesn't seem to respond well to sitting for very long as I presume your car did. Eliminating the easiest and/or cheapest possibilities first is always the way I work, though.

Just out of curiosity, what were your findings when you checked the system's control pressure?

Control pressure warm without vacuum was 2.3 bar should be 2.8-3.2. Control pressure warm with vacuum was 3 bar should be 3.4 - 3.8.