Thanks for this informative thread.
I made a WVO conversion also with tank --> filter --> 3-way valve --> lift pump --> IP. (30k miles, 2 years on WVO)
Once I was on a trip through Utah in the winter. It was 10 below zero F, and the WVO was freezing at the coolant-heated WVO filter. The stock tank was full of WVO so mixing in dino wasn't an option without getting under the car and draining first. So I decided to run from my 5 gallon diesel tank, which doesn't have a gauge.
Needless to say I ran out of fuel. I was forced to purge on the side of the road, in the cold, with two toddlers and the wife in the car. In Utah. Not. Good.
I managed to do it by carefully switching between the WVO side (which had fuel at the valve inlet) and the diesel side (which had air at the valve inlet). I'd replaced the stock primer pump with a somewhat beefier version, which I think helped. I pumped on WVO to get air out of the lift pump and IP. Then I'd switch back and forth, pumping on diesel a couple of times until it began to feel limp, then having my wife switch back to WVO and pump 'til it buzzed, then switch back to diesel etc. It took about an hour and I lost a lot of skin on my hand due to all that extra rubber fuel line near the IP. What a huge relief to finally hear that thing buzz with the diesel flowing through.
Lessons learned: have an electric heater on the WVO filter if driving in the cold. When converting add a second full-sized tank (from the junk yard) for the WVO and keep the stock tank for the diesel. And NEVER, NEVER run out of fuel! If I were ever in a similar situation again I'd stop and top off the diesel every seventy miles just to be ridiculously on the safe side.
Sorry to bump this old thread, but maybe that will help or at least entertain somebody.
