I have a 1985 F-150. straight 6 motor. It has sat for a couple years without running and I am trying to get her running again.

It cranks over good but wont fire up. If I pour gas down the carb it fires right up and runs till the gas in the carb is gone and dies.

It also has dual tanks and I made sure I had some gas in both tanks.

Its obviously not getting fuel to the carb, but where should I start to look for the problem?

 

Replace the fuel filter if it has been sitting.
If that doesn't work, use a compressor to blow out the fuel lines.
I'm not at all familiar with your model year. Does your truck have electric in-tank pumps or just a mech pump on the engine? If there are electric pumps, check the relay. If there's just the mech pump check it to make sure it's working. If the diaphragm is rotted out - and it well could be - it could be dumping gasoline into your crankcase, definitely not a good thing for engine life.

While you're at it replace any fuel lines that are looking brittle or rotted.

 

If the truck sat for that long you need to empty the tanks and get the water out, you now have a gas/water mixture and is is more water than gas, don't count on adding gas to the tank, it will just stay a water/gas mixture. Had the same problem with mine, but it would barely run and the exhaust smelled like a junkyard.

 

In the carb, of course. Is the needle valve stuck?

 

x2^ Also see if the jets aren't gummed closed, had that problem before.

 

I had a similar problem with my '88. Bought it from my father in law. hadn't ran in about ten years. I don't know what you have for a fuel pump, but in mine there were three. 1 in each tank and one on the frame just to the front of the driverside door. I must have replaced the pumps in each tank twice before I finally changed the pump on the frame. Once I relplaced the one on the frame, it was all good. No more problems with fuel delivery. Couple hints, when you turn the key, before you move it to the start position, listen to hear the pumps turn on, if you do not hear them, then you have found your problem. Also, you do not need both tanks to work, fix one just to get it running. You got a great engine bud, 300 straight six is a beast, and once it runs, it never quits. mine had 226,000 miles on it when i sold it.

 

'85 300ci uses a mechanical fuel pump.