Sounds exactly like the problem I had with my 84 vanagon and my
father-in-law's 85. It's being 'flooded' by a 
malfunctioning coolant temp sensor near the water pump.

Here's a trick to start it. In the engine compartment, open the black box
over the ignition coil on the left side. Unplug the relays and start it. It
will start on just the residual pressure in the fuel system. Immediately
plug the relays back in to turn the fuel pump back on.( Works better with
two people or how fast can you run around back?)
I confirmed the problem with the sensor sending a 'cold' signal to the
computer even when warm by a trick from my mechanic. Go to Radio Shack etc.
and buy a half watt 100 ohm resistor. 

When this happens again (mine was very intermittant and frustrating) unplug
the lead to the sensor . It's one of those special ones with the spring
clip retainer in the thermostat housing out of the water pump. Push the
resistor in the harness and hold in with a bit of tape. This will give a
'warm' signal to the computer and if  it starts and runs ok, then buy a new
sensor. It's a Bosch part I got from my independent shop for about $35.
(It's on page 19.8 in my Bentley manual)

I drove home from Eastern WA to SoCal with the resistor in this way.
Hope this is of help.
Jess Lopatynski
87 GL
85 GTI