I HAVE A 1990 FORD E-150 VAN 351 W I WANT TO PUT IN A AVITAL REMOTE START CAN I IN THIS VAN ?

If the Van is Throttle Body Injected (TBI) or Fuel Injected (FI)
YES

I can supply you with wiring Guide, that shows the colors & locations of the wires you need

Let me know.........

Here is 2 different Guides, which show color & location
The reason there are 2, is sometimes different companies offer other areas of coverage
Door Locks are + Positive Pulse
You may have to add 2 Relays to activate Door Locks, as the Avital may not have the ability to activate the older Door Locks

if you need further, let me know

click links below

WIRING GUIDE

WIRING GUIDE

CAN I GET THE WIRING GUIDE TO DO THAT ?

If you do not want any of the other accessories & "only" want Remote Start, do not connect any of the other wires of the Avital, except Remote Start wires, Ground & +

Not sure if you fully understand my answer

The Wiring Guides I provided will give you the info you need
Compare the Wiring Instructions of your Avital to the Wiring Guides I provided & "only" connect the Remote Start wires shown in the Avital Instructions plus the Brake wire

this is not that difficult