Bulley wrote:
>
>'cept your FI van won't typically backfire, as the FI is off when the
>ignition is off. Unburned fuel in the exhaust system is what causes the
>type of backfire you describe. A carbureted vehicle *can* suck fuel in from
>the acceleration pump if'n you were to try this, and turn the ignition on
>and off.

This reminds me of days gone by...
A consequence of having too much access to junkyard parts struck my friend.
He had an 82 rabbit, was diesel but converted to gas/carb.  He drilled and
tapped his tailpipe for a sparkplug and rigged a windshield wiper motor to
turn an extra distributor in the hatchback area of the car.  A coil was
hooked up and the high tension lead attached to a sparkplug in the tailpipe.
He would turn the car off while driving and pump the accelerator like mad to
fill the intake with gas.  The motor (still turning) becomes a big air pump
and blows the raw fuel out of the tail pipe.  At this point the tailpipe
spark plug ignition is engaged.
He would regularly shoot three foot blue flames out the pipe.  I recall many
nights cruising around, pulling to a light after playing around and watching
the cars in back stop a good twenty feet behind us:)