Is the starter turning the engine each time? Or is the starter just spinning some of the times, without turning the engine. If the starter is acting correctly every time, then do this. Next time it will not start turn the swich to run, but not to start. See if the fuel pump runs for a few seconds. It will not be loud, so have the radio off and your seat belt on so the bell will not chime. If the fuel pump does not prime, the pump may be going bad.

I don't know how many people know this, but if you have an electronic fuel pump and it leaves you stranded, usually you can beat the side of the fuel tank and get it to come back for a bit. That fix WILL NOT last long, but it will get you home 9 times out of 10. Actually I've never seen one it didn't work on. Granted sometimes one person was trying to start the vehicle as I was pounding on the fuel tank with my fist. But it has worked 3 times for me in various vehicles.

 

So, must one bang at the SIDE of the tank, not the bottom? How can you get at the side with some force as there is hardly any room for a hit?

 

Yes, the engine turns over every time. I've heard of the beating on the gas tank trick. In fact, that method works with many electric motors (window motors, starters, etc..). The engine runs great when it's started, and I replaced the fuel sending unit with the fuel pump like last spring or fall or so, which leads me to believe it's not the pump. But, I'll look into that.

 

Another one for your list. Leaking fuel injectors are infamous for bleeding pressure off causing hard starts. Connect a pressure gauge and see what you get after it sits a while.

 

Having the pressure gauge on the fuel rail when starting it will also help you determine if you're pump is flaky. Just because you replaced it recently, doesn't mean it couldn't go bad. I replaced one once, and within a month, I had to replace it again. The pump fell apart in the tank .....

Another thought. Some morning, when you start it, put your foot to the floor, then turn the key. If it starts up differently, you have an injector leakage problem. If no different, it's most likely your pump.

A way off the wall possibility, could be your pump relay. Find it and swap it with another one like it, in the box. Make sure the contacts are clean.

 

I don't think anyone has said this but I think you have a clogged filter. Your van is getting gas sometimes and not others.
My van left me stranded and the next day after trailering it home it started no problem for my mechanic. Just by moving it around the sludge in the filter must have moved enough to get fuel presure at the rail. He delivered it back to me and said everything was fine. I got in to go to town and cranked it all day with nothing.
Replaced filter and van starts first time every time.
When it refuses to start go to the fuel rail and remove the black plastic cap. With a small screwdriver push the pin 'GENTLY!!' it will ooze gas if you have pressure. This is no indication that you have enough pressure.

 

I replaced my fuel filter way late they said..at about 130,000 miles or so. I was disappointed, as it was clean as a whistle. BUT, how is one to know???