10psi at the IP supply at idle, 9 at full load. It's not the tank screen, filters, overflow or lift pump I don't think.

I have a looped return and single switchover valve so almost zero chance I am contaminating one tank with contents of the other.

Grabbing $100 80k mile MW pump locally tomorrow.

And yes, I have been doing a little soul searching on the alternative fuel. I have several friends who have been doing this for a long time in 12 valves and this vintage Mercedes with great results. I don't think I'm ready to give up yet as I really believe my current issues are caused by a bad batch of veg oil. If I can't get it right with fuel I have more confidence in, I'll probably throw in the towel.

This is a $500 kinda rusty car. Big reason I bought it was to experiment with this stuff. I knew things like this were a risk, but I also enjoy the learning process (even if it does ultimately mean I'm better off running pump fuel.)