The black part on the top of the pickup is the vent. It allows air in and out during refueling and consumption. If it turns upside down, a valve falls against a seat and seals it off. You need to close that to keep the air in the tank. You could probably put a piece of hose on the barb, clamp it on, then kink or plug the hose.

On the injectors, there are the drain or returns on them. This drains the fuel that gets into the spring chamber. If the spring chambers are full of fuel, then they are hydraulically locked, and will not deliver the fuel. Just like an externally drained valve in a hydraulic system (pressure reducing valve, sequence valve, etc.) I was thinking that maybe there is a blockage downstream of the injectors that would stop them from popping off, and thus no start.

It doesn`t completely jive since once it starts it runs good, but it is something that you might check into.

 

I've pressurized at least 50 different tanks and have never run into this problem.