Just started having this problem after I changed the fuel filter. Truck will start initially, and idle. I can drive it around for a while if I drive easy on it. If I put it under any load it will die out almost like fuel starvation. Trying to see if anyone has gone through this? At the moment I am thinking it is either the fuel pump going bad or possible the Cam Position Sensor, although that is feeling like a long shot. None the less any input would be welcome at this point.

 

Welcome to FTE. If you scroll down further you will find the 99-03 7.3 section. You'll likely get more answers there. When you say it feels like fuel starvation I assume you mean it sputters before it dies? Do you get a check engine light? Any other dash lights that come on, don't go off, or don't come on? Any other symptoms you can tell us about.

The CPS is a $30 fix if you want to try that. If you need instructions on how to change let me know and I'll give you a link to instructions.

 

Yes it sputters. Then it will not start. If I let it sit for about 5-10 minutes it will start and sometimes enough to get it moving again. Mind if I ask what CPS is? I am thinking Cam Position Sensor.

A couple of lights come on, including the check engine light. No codes are available though.

This all started after I changed the fuel filter, which I thought was bad. I have changed back to Puralator filter now. Now the truck will idle for what seems to be forever. Only under load will it die out.

 

Yes the CPS is Cam Position Sensor. It can cause all sorts of problems. What other lights come on besides the check engine light? If you try and restart before the 5 - 10 minute period does your wait to start light function normally (come on for a few seconds then go off)?

 

Once I kill the ignition, and attempt to start it back up everything is normal again, except for some times it will not start. After changing the fuel filter, I drove it around the neighboorhood for about 15 minutes. Then just before getting back to the house I stepped on it a bit harder and it died out again. I am trying very hard to remember if the RPM guage was registering when it would not start, and can't remember. I have heard that is also a tell tale sin of a bad CPS.

 

On some models the tach is a good sign of a faulty CPS. A wait to start light that does not go off can be a sign of chaffed wiring. I see you found the 7.3 section you're likely to get many more responses out of that thread, although you may have to wait until tomorrow.

Have you checked your oil? The fuel injectors are powered by high pressure oil. Old or low oil levels can affect how the vehicle runs.

 

I check the oil regularly but haven't since this problem has started. | will in the morning though. I am also going to try to get it to fail again tomorrow and then see if I drain the the fuel/water separator bowl if there is any fuel. I am thinking this would be a test for a bad fuel pump?

 

Definitely sounds like a fuel starvation problem. I had a problem like that just today...

How much fuel is in the tank? The un-modified pickup sometimes has trouble priming when it's low. It sounds like you've been dealing with it for some time, so I'm thinking you must've filled up by now. Since it happened when you changed the filter, go back in there and make sure there's no trash in there and it's for sure installed properly. It could be the pump, but that's a pretty big coincidence.

Also, there are screens in the tank on the foot and in the mixing chamber. And one on the input to the pump as well. A lot of us have done the "Hutch" mod to our trucks, which modifes & replaces many parts between the pump & the tank. While unrelated really to what you're looking at, it's a good thing to know about so you have an idea of what you're dealing with on the other side of the fuel system. Here's a link to the mod:
http://guzzle.rbmicro.com/hutch.html

My problem today was bad/dirty fuel that plugged up my pre-pump filter. It did exactly what it was supposed to do and pull the dirt out of the tank (the stock mixing chamber would've been plugged if it was still there), but keep it from the pump. I was able to replace the filter in the parts store parking lot instead of having it towed home to drop the tank & clean out (or replace) the mixing chamber.

 

First thanks to F350-6 for all the fast replies and info, and to Izzy351. This is a real good forum, with excellent input from members.

Here is where I am at now. At the suggestion of filling the tank up... I had originally put 5g in when I thought I had run out of fuel. I eased the truck down to the local Hess and filled it up. Man was it thirsty, took a hare over 30g, and a $100 out of my wallet. Biodiesel to come!!!!

I first noticed that the fuel gage would only show half a tank. About 30-40 minutes later it finally raised to show a full tank. I am thinking I have fuel pickup/sender issues.. possible the float mechanism. So it is perhaps time to install the Hutch Mod.

Once I got the truck back into where I live, I pushed on it pretty hard and all went well.

Interested in anyones thoughts here, mostly trying to validate my thinking.

 

Well the fuel mods won't hurt anything, and it will give you a chance to look around inside your tank to see how everything looks. You'll just need to wait until your tanks is down close to empty so you can move it around. If you decide to do this I'd carry 10 gallons of fuel with you in some jugs so you don't get stuck somewhere.

As Joe said, low fuel can cause problems at the pick up tube.

 

Here's the deal with the stock fuel pick-up: There is an auxiliary input well above the bottom of the tank that can suck air when below a 1/4, and as I mentioned earlier, the return line connects to a mixing chamber that goes straight to the pump suction line. You can also suck air through the crappy quick disconnects on the suction side of the pump that are designed for pressure, not suction. So now you have air in the system when you opened the filter bowl, a tank with the fuel level below the aux input sucking air, air coming in through the crappy connectors on the suction line before the pump, and whatever air that is getting back to the tank from the fuel bowl is getting sucked right back into pump at the mixing chamber. Makes you wonder how it works at all doesn't it?? Without in-tank mods, the truck is likely running on foamy fuel, and probably pure foam when below ~1/4 tank. That's why the Hutch is such a great mod.

The Harpoon is not related at all, but make sure you do that if/when you drop the tank to do the mods. Your tank will fill up fuller and faster than ever before...