Just wanted to ask if anyone has changed a fuel pump and is it easy or hard and do you drop the gas tank or not, etc. The check engine light came on this week and I took it to a auto parts store and they checked the code for me. The code was for lean fuel, he showed me what the options were, one was that the fuel pressure was low and that could be the fuel pump and the other one was fuel filter could be plugged. I am on my way out to change the fuel filter right now. But thought I would get a jump on the next step if this don't fix it. It would you guys if I told you that I have an 05 F250 Super Duty with a 5.4 engine. Thanks in advance for any help and or ideas I can get. This site is awesome so Thanks to those who keep it going.

 

Well, my unit is a '99 F250 superduty 4x4 crew cab with a long box. I haven't dealt with an '05, but my experience was that I dropped the tank and changed out the entire in tank assembly. I have heard of others removing or lifting the bed to gain access.

If you drop the tank, I strongly advise looking carefully to be sure you have disconnected all the pipes and hoses. On mine there is a vent hose on the top rear that can be accessed by removing the spare tire.

Having 2 people helps in dropping the tank, it is a little awkward.

There is a large threaded ring on top that holds the pipe assembly in place, and it would be a good thing to have one of the special wrenches to deal with that. Although I just carefully used a mallet and punch to remove it, the risk of breakage is there.

I drove around until the tank was very low on fuel to lighten it, and cleaned the dirt out of it as best I could while I had it open. It had accumulated a fair amount of contamination, as the gasket under the large ring assembly had fallen out of place or was not installed properly to begin with (it was that way when I bought the truck used).

One last thought, you didn't say if the fuel pressure at the injector rail had actually been measured or not. If not, I would advise doing so before throwing a new pump at it. Assuming it's the same as my '99 V10, it should be around 30 to 40 psi at the rail, rising somewhat under load. If it is low and/or falls off under heavy load, there is a problem with supply, either clogging or bad pump.

 

Thanks very much for the reply. You are dealing with a weekend mechanic, is it easy to check the pressure at the rail? As you can tell, I am not at sure how to do that. Any help would be awesome. Thanks again.

 

No worries, just a DIYer myself. Again, assuming it is similiar to my '99 V10 (you know what happens when you assume), there should be a schrader valve (similar to a tire stem valve) on the passenger side fuel rail, which is the silvery pipe running across the tops of the fuel injectors. A fuel pressure test gauge would need to be connected to this schrader valve temporarily.

There are various pressure tests that can be run. There is the static test, just turning the ignition on and off a few times to see what kind of static pressure can build up and watching to see how fast it leaks down. It shouldn't leak down very quickly at all. Then there is the idle test with the engine idling. It is also important to check the pressure under load, I usually do this by using a gauge with a hose long enough to have it setting on the outside of the windshield where I can read it, then drive on a deserted road somewhere to check it by giving it the onion a few times.

I use an Actron gauge kit, available for around $50 various places. It includes a gauge with a reasonably long hose and various adapters for different kinds of spigots including the schrader valve.

On my engine the normal pressure would be around 30 to 40 psi at idle, rising slightly under load due to the pressure regulator action.

 

if it is indeed the fuel pump assy, id pull the bed if possible. sure beats fighting with rusty straps,a bulky tank, and at least on my ranger wasnt too bad a job to do. unbolt the filler neck from the bed, unplug the wiring harness for the taillights, remove the 6 bed bolts (that was the worst part for me) then lift the bed off. i used a small farm tractor with forklift forks on the bucket & a couple of 2x4's under the bedrails. probably could have lifted it on & off with 2 people. a fullsize box might take 4 people though. id start with checking the fuel pressure though. if its low check the filter and regulator. you might get lucky and it only be a 15 dollar fuel filter.