Ok, here is my problem. The other day I was servicing my truck and putting on a new tensioner and mounting bracket and after I was done I started my truck and started looking everything over like usuall. The truck was running fine, had good oil pressure, and sounded good. I had noticed a fuel smell and was looking at the lift pump and the truck died. There was some fuel in the valley but not a whole lot. I started it back up and it fired right back up and went to a really rough idle and died instantly. I did this about 8 times and had the same result. I switch from my front tank to the rear thinking it might be a bad tank pump and the same thing twice. Finally she fired the third time and ran fine. Bad front tank pump........right? Well, I hauled cattle yesterday and put 250 miles on the truck with only a slight hint of this problem, i flipped tanks to the back again and it came out of it. Still rear tank pump i thought. I was on my last load and flipped it to the front tank again to get as much fuel out of it before i dropped the tank and the thing ran fine for 100 miles. I am now baffled. So this morning I went out and started it, fired right up and idled for about 2 minutes and the same thing, dead. Start it up again and it does the same thing every time on both tanks. Is this a sign that the lift pump is out or something else. The rough idle sounds way to bad to be a dirty injector or a cylinder missing. It really sounds like it is starved for fuel? Changed filter today and still have the problem?????????? Please shed some light on this before i spend anymore money, after all i am a poor college kid! Thanks.

 

could be several things. I would put my money on one of two. Either the cps(cam sensor) or the wiring harness from the valve cover to the injectors. i have had both problems.

the first problem, cps, my truck would die at odd times and then difficult to start again.

the second problem, wire harness, mine would run like a 53 studebaker running on 3 cylinders for a period of time, 5 miles or so, and then run fine for 5 miles or so. I was sick when it started running like this. didnt have any idea what it was but desided to drive it the 20 miles home. Shortly after starting on the drive home it started running fine. but before making it home it started again.

I bought a cps off Ebay for 50. it was motorcraft, new in sealed package.

My wire harness came from the dealer, and they stuck it to me. dont know if you can get these anywhere else. I dont know how to check this without removing the valve covers. valve cover gaskets are expensive for these psd but have heard some people reuse.

good luck

 

It sounds like the CPS aka Crank Position Sensor I don't think the leaking fuel pump is doing it as mine is leaking and the truck runs fine.

I was told when your cranking it over and you don't see the tach needle moving the CPS is going.

 

Sounds like CPS. I had a small fuel leak on the fuel filter housing. I replaced the fuel heater and went for a test drive and the truck died. I restarted and ran fine for 30 miles and then died again. The tach did not move replaced the CPS and truck came back to life.

 

powerstrokefreak,
You should know there are NO fuel pumps in the tanks. The pump in the engine valley is the only fuel pump on your truck. All that is in the tanks, is the fuel level sender, and a rubber boot with a plastic screen on the end of the suction pickup.

Now, let's go back to the fuel leak you had. Is it still leaking? Can you confirm it's leaking from your pump? The fuel filter housing is known to rot out from water sitting in the bottom too long.

It almost sounds as if a fuel line somewhere is sucking air, and not getting enough fuel. Since it is doing this on both tanks, it might be anywhere after the tank selector valve to the fuel pump. If there is a leak by your pump, maybe that's where it's getting air into the system.

I wouldn't discount the cam position sensor, but you don't want to just start changing parts for fun, unless you already have a sensor on hand to try. Do you know anyone with a code scanner that could pull the codes for you?

Ken

 

New information! I am sure it's not the cps because I changed it not to long back and none of the symptoms match it. Tach moves and starts every time. Put a pressure tester on the schader valve on the fuel bown and i have good pressure, 50-60 psi at idle. Was wondering if it could be the pressure regulator. Someone had the same problem and it ended up the regulator was bad and was restricting fuel to the fuel bowl. Sounds like it could be my problem.

 

Does it smoke any when it's running rough? Generally if it's pushing air through the injectors it will blow a blue/white smoke until it smooths out.