99 Quest Fuel Injector Fuse issue

[trentoon]

1999 Quest. Injector fuse keeps burning up. Fuel pump working all the way thru filter. I try a new 10amp fuse..get some ignition..then blown. Van just had upper radiator hose replaced but I don't see anything in that area that could relate. Van ran 300 miles since hose replacement then wouldn't start after parking. Van has had problems burning out heater motor relays resulting in heater fan only working on #4 (high). Replaced that relay with sucess for 1 month then back to same heater problem. Could bad Heater moter be causing? Research says check injector relay and sensor. Is there one of each for every cylinder. Other research says cheak cam and crank sensor. This must be some little electric pulg in box needing replacing..right?

Optional Information:
Year: 1999
Make: Nissan

Already Tried:
Check fuel pump/filter. Working. Starter fluid to carb and car ran...so I have spark...just no gas

I established a starting sequence that works temporily.....Spray Starter fluid in...turn over and while running on eather, put 10 amp fuse into fuseblock. Will run on gas just right until you adjust the throttel at all..then you get a fuse blowout and all stops.