I used the procedure found here: http://www.brickboard.com/AWD/index.htm?id=742009
to try to find if any obvious things are causing my 3-1-5 code.

What I found is: plenty of vacuum in line to the manifold, plenty of vacuum at charcoal canister when the purge valve is activated. When the purge valve is not activated, I get no vacuum at the canister (in hose that goes over to the purge valve).

Not knowing exactly what I would find, I checked the vapor inlet from the gas tank to the canister, and I found a reduced vacuum compared with the outlet when the purge valve is activated. This seems ok, since the vacuum observed on the outlet to the purge valve has to pull through the charcoal. All the in's and out's of the canister were clear.

This is the shop procedure, according to a post in the archives, to check the Evap purge valve and associated hoses.

Is there anyone out there that has another suggestion before I pursue Klaus' idea of the fuel pump regulator? I don't have an easy way to check that, which is why I ask...

Thanks, Don