I just bought a 2000 lightning and on the 2nd day of owning it I went to start it and it idles really rough and if you give it any throttle it just dies out. I was at work and the only way to get it home was to unplug the mass air meter and limp home. I thought the mass air was cooked so I bought a 90mm FRPP maf and it still does it. it threw no codes when it idled rough and died, only time it threw codes is when I unplugged the maf to get home. the truck only has 69,000 on it. the only thing I did was clean out the K@N filter, and the rest of truck is stock.. just want to be pointed in right direction before I take it back to the dealer I bought it from. thanks.

 

The first thing I would do is put the stock meter back on the truck and clean your IAC valve. Sometimes they stick due to carbon build up and can cause the issue you are having. It looks like a metal cylinder and it is located on the left hand side of the upper intake. Just unplug it, remove the bolts, spray it out with throttle body cleaner and gently work the plunger back and forth with a screwdriver, and reinstall it.

The 2000 L's came with a 80mm mass air and the 90mm you bought won't work unless you retune for it. The 90mm is a good upgrade so keep it and reintall it when you decide to mod the truck.

Disconnect your battery while you are working on the IAC and your SES light should go off. Before you reinstall the 80mm, give the little wire inside it a shot of TB cleaner to remove any oil or dirt it may have accumulated over time. Just be careful and don't damage or break the wire inside.

Let us know if it fixes the problem.

Randy

 

Check for loose vacume line under air intake

 

First check the fuel pump resistor (located on the innercooler pump bracket, under the radiator):

https://www.f150online.com/forums/sh...d.php?t=227200

If that's good, drop the tank and check the hose connections on the pumps:

https://www.f150online.com/forums/sh...d.php?t=123850

https://www.f150online.com/forums/sh...d.php?t=228017

Hope these help, good luck.

 

It sure sounds like a hose came off of one of the fuel pumps.

Jake...

 

took it to the dealer and they said that it only had 10 pounds of fuel pressure, and that the pumps were bad. after fighting tooth and nail with these ****heads at the ford dealer they finnaly ate the cost of the new pumps. and I got the old pickup assembly that they said had the bad fuel pumps. I looked quickly at it and didn't see any of the hoses off of the pump. thanks to everyone for your help you guys sure had me going in the right direction... thanks again