86 5.0 EFI f150: New tank pump, new supply line from filter, new fuel relay, both pumps are working, all I get at the schrader valve is air. Anybody help???

 

Let the air out until the fuel gets there?

 

yep just keep bleeding the air out

 

I've cycled the key 25-30 times running the pumps up for the better part of the afternoon and still nothing but pressured air. I don't know, it's got me stumped, bout time to tow it to the shop and pay out the wazoo for something that could be fixed with a little help from someone. Thank you for your response, I'll keep trying tomorrow I guess.

 

How much gas did you put in the tank? I would also take the gas fill cap off and see if that made any difference(in case some of the emissions lines are blocked).

 

yeah, not trying to be a D**K but you did put gas in it right? I know I've done dumber stuff.

 

Good call, could be a low tank. I know a guy that let a non-starting chevy sit for over a year before he asked me to take a look at it. I heard the pump run with the ignition, but not a drop of gas at the throttle body. He swore up and down it had an 1/8th of a tank. A gallon and a half out of the lawnmower gas can I had in the truck and it fired right up. I think he told his wife I cleaned the electrical connections on the fuel pump or something. (I hope she never finds out she was walking so much just because the truck needed gas. There will be holy heck to pay.)

That said, fuel pumps don't compress air real well. So if you're really getting pressurized air at the fuel rail I'd think the fuel is pushing it and all you'd have to do is keep bleeding until it got there. Try taking the tubing loose at the fuel filter and se if you are getting fuel that far. (After putting some gas in the tank for good measure.)

 

Low gas was my first thought, I'd put 4-4.5 gal. in 2 weeks ago and added another 4.5 Saturday, so I know I've got almost a half a tank(16gal. tank). Here's a twist, when I bought the after market intank pump, I installed in the sending unit and was ready to go back in the tank when I thought about polarity. So, got a bucket, poured gas in the bucket, got a couple of wires and a battery(12v), I wired it the way the old one was,it ran backwards!!!! So, I swapped wires and it pumped fuel UP instead of blowing bubbles DOWN. I used te sending unit male connections to wire to. Red to red, you know and so on. What about the gas cap do I need to know??Thanks guys, I'll keep cycling the key and bleeding and see what happens today. Will pull some fuel lines today and see how far gas is traveling in the lines.

 

Well, I found that the in tank pump was wired bassakward, rewired, have fuel through the rail and back to the tank. It will not stay running now. Squirt gas into the intake, it runs and dies. Try to restart, it tries but can't stay running. Where to from here?? Something about the thing mounted on the distributor???

 

The gas cap is sealed in these trucks. The only way air gets into the tank is through the emissions lines going to the charcoal canister. These were the little lines running over and up the passenger side. I thought you could possibly be airlocked. No air in, means the fuel can't get out.

I am suspicious too of your "aftermarket" pump. You did not go to the store and get a replacement pump that fits your truck? If it's something weird, what pressure rating does the pump have?

 

Bought the pump at Auto Zone out of the computer at the counter. Had the old one with me and compared them, they the same. But, on the bench test, it ran backwards from the old one, unless I got mixed up on the install. At any rate, I've got good fuel to the rail and back to the tank, no fuel from the pressure regulator vacuum line, it tries to start from a "cold" start postion, but just won't hang in there. The more I try after that, the less it tries to bang off. When I say "cold start" I mean after it sits awhile. Did a poor man code pull,22,63,22,63. MAP and TPS the best I could figure. Now, do I change these out or what?

 

It's very unusual that both those sensors would go out at once. You might have a wire loose or corroded on the engine harness. See if you have voltage going to the TPS and the MAP.

 

I will check that out as soon as I get a volt meter borrowed. Thanks

 

Franklin2, checked voltage to the TPS, showed 5.23v. Unplugged the plug and pulled olms on the leads to the sensor and it showed open on all three pins. Is this normal? I'm not to smart ehen it comes to electrics.

 

No. You should have readings on all three legs. Make sure your ohmmeter is in the correct range, if it's not auto-ranging.