my 86 f-150 with the 302 efi wont start it runs on propane and gas i can get it to run on propane but cant get it to run on gas ive put a new fuel pump in tank and filter and it still wont start

 

Never mind, I read it incorrectly. Do the spark plugs look good? Thats a cheap place to start. Do you hear a noise under you feet when you turn the key befor you start the engine? If not it could be the fuel pump there.

 

the spark plugs are good i can run it on propane but not gas

 

This could be a long shot, but does it have dual tanks? and maybe the valve is half way? idk what else it could be on the fuel line. I don't think its in the computer if you can run propane.

 

its got the front tank but the rear tank got replaced with propane tanks

 

i was just checking to see if the fuel inertia switch was on or off. should the white tab on top be up or down? mine is down. how do you reset this?appreciate all the help i can get

 

just push down on the inertia switch.is your truck fuel injected?it probably has something to do with the switch,that switches from propane to gas.check all of your fuses,there could also be a wire broken ,or come loose.also check all of your grounds.

 

i pushed switch down no change.when i switch over to gas and turn the key i can here the rail pump buzz for a few seconds. could it be anything to do with the oil pressure switch that activates the relay? if so where and how do i check that?? thanks for the sugestions guys, please keep them comeing i really need to get this truck running on gas

 

on your starter relay there should be your two large wires and two small ones.one is to energize the relay,the other one turns the pump on while you are cranking the engine only. you could jump this out with a live wire and see if it starts.the relay should be by the power brake booster.i believe there is a fuel pump wiring diagram in the stickies area.good luck

 

so far I have half tank of gas,new fuel pump in tank,rail pump buzzes for a few seconds when i turn ignition on. new fuel filter. Inertia switch is good.I checked dual fuel switch and it works proper.Relay switch has power going to it from the solenoid relay when i turn the ignition on.The only thing i havent tried is pull the line of in front of the fuel filter to see if fuel is actually being pumped through since I dont smell any gas when turning the motor over

 

Checking the output rate & pressure at the engine would be one of my first diagnostic
methods if I was in your situation.

 

Well guys I finally got it running on gas.I pulled the fuel line of in front of the rail pump.I turned the ignition on ,listend for the buzz at the rail pump then checked to see if there was fuel in the bucket I put below the line,which there was.I turned the truck over and holy crap it fired up.Ran it till it died and then I hooked the fuel line back up.Turned the ignition of and on a few times to pressure up the system and it fired back up and ran.IT now runs awesome,maybe it was vapor locked I dont know.Thanks guys for all your help and sugestions !!!!!!