There are many WVO conversion systems on the road that need an operation manual to run them. Wait until this gauge is...then turn this...10minutes before you stop...Make sure....ect. When I set out to develop the system for my truck, I coined the phrase "wife proof operation". Now don't get me wrong, my wife is a very intelligent woman; medical degree and everything. However, in order for her to drive my truck (and use WVO) on occasion, the system really has to do it all.
Fast forward about two years: My wife and I are driving home from a weekend in Florida (1000 WVO trip) and I made the comment. "I am really impressed how reliable the WVO system is on this truck!". I almost heard the bell toll.
A week or so later, we were in the process of getting my wife a new car but had just sold her old one the day before. ( My wife is three months pregnant and a new car is apparently part of the process.) Anyway she had to drive my truck to work about an hour away. On the way back, she is flagged to pull over because the truck is literally spraying diesel onto the road. Somehow, the purge solenoid broke off the valve body exposing 70psi fuel which, was getting loose in a hurry. She of course phoned me (at home without a vehicle) so I could give instructions to the guy that pulled her over to get the truck back in running order.
Now, I need to explain a few things. I had planned on failure in the design; I had placed quarter turn ball valves on the fuel line at the pump and on the purge line. The idea being that if something failed, I would be able to simply turn the valve to isolate the veggie system so that it would operate as normal on diesel. However, the ball valve was behind the solenoid valve. While I expected it could fail, I didn't consider that it would break off. The valves could not isolate the leak.
Back at the truck on the side of the road: a man literally walking by stopped to help and was able to thread to solenoid back into the valve. It still leaked but was good enough to get her home. Well almost, she ran out of diesel turning into our neighborhood and was pushed to the side of the road (again) by a couple firemen that happened to be behind her. I got a ride from my neighbor to my stranded wife and, with a crescent wrench and a pair of pliers, removed the broken valve and simply reconnected the two loose ends together. Since the valve is normally closed the closed ball valve replaced normal operation. Three minutes later, I was able to start the truck on veggie and drive the truck and wife home.
Is there a lesson to the story? I don't know, probably if it can go wrong it will. Expect it and plan for it. Adding a fuel system to your vehicle should make it more reliable not less so ensure that you can totally isolate the veggie fuel system and return the fuel system back to a stock configuration. Its nothing short of amazing how reliable vehicles are today. As far as WVO fuel systems go, mine is certainly among the best but I always bring a tool box and a spare filter, just in case.