Hey guys. I'm new here and I'll do the best I can to keep this simple. I have an '04 F550 with the 6.0, it's a 16,000lb service body with 168K on it. Had it since April. I know in March (before purchase) at least SOME injectors were changed, maybe all of them. This is all the info I have about this repair. Since, I've had injector cups replaced which significantly improved the running of the truck. Oil changes are up to date.

After the truck has warmed up, I have a loss of power when power is demanded most. It is particularly evident under hard acceleration (merging onto interstates) or while climbing hills (coming out of the local tunnels). The truck may downshift, but no matter how much gas you give it, the RPM's remain constant and speed won't increase. It doesn't seem to be running especially rough, just an even loss of power. If the hill is steep enough, I will lose more and more speed, sometimes going from 65 MPH to 30 or less. Shutting the truck down for 5 or 10 minutes sometimes helps, often doesn't. Driving on city streets with easy acceleration seems ALMOST normal, it just takes a slight amount more pedal effort to accelerate. This has been a problem for a month or so. I see no smoke from the tailpipe, no CEL (although the light does work).

Through my research across forums, I'm thinking my problem is either IDM, IPR, HPOil leak, bad HPOP, damaged wiring to the above listed, or bad injectors (maybe some weren't changed). I was wondering if you guys had any pointers for me here. The problem started just before I had the injector cups replaced and it seems no different through that repair.

Because of the cost of the injector cups (pulling the cab and heads) I'm really strapped right now. I depend on this truck daily and I'm just looking for what the most likely problem may be. I'm wondering which of the above items are low cost that I can "throw" at it or what inexpensive "fixes" may be common for these symptoms. As far as troubleshooting is concerned, I don't have access to a scan tool of any type at this time. I don't even currently have access to an air compressor.

If there are some things I can check out visually or some inexpensive parts I could easily throw at it I will, otherwise each time I drive I will chose my routes wisely until I can afford another multi-thousand dollar repair bill. I have done extensive work on gas vehicles (motor jobs, etc) but this is my first diesel. Sorry for the long post and thanks in advance!

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Just to expand a little more, the problem hasn't happened yet outside this scenario:

I start the truck cold and drive it to a job site (it's fine). The drive can be anywhere from 5 minutes to just over an hour. The truck idles for 1-6 hours as I work (I need it running because I often use the hydraulic system and/or inverter while I work, sometimes I just use the DC lights though). I drive the truck home or to the next job -- this is when the problems start.

 

Does the truck start ok when hot? like if you turn it off for 5 minutes and start it, does it start right up? if yes then it is not a High Pressure Oil leak, if no then you have a high pressure oil leak. Not starting when hot is ussually the first sighn of a HPoil leak.
I am pretty sure you are going to find the EGR VALVE is tottally clogged and probably hanging open causing this problem, very common with trucks that Idle alot. Most times it is an easy fix but I do recommend that you buy an Oring kit for the EGR valve before you remove it to clean. the EGR valve sits just to the left of the intake elbow at front of the engine, there is a multi pin connector coming straight out of the top of it, it will have 2 -8mm or 2 10mm bolts holding it down/I forget wich size/ they can be a PITA to get out and you have to be careful not to bend it up. What you want to do is either use 2 screw drivers or small prybars to pry up the 2 flanges where the bolts were, you will have to take it easy and be patient but just keep working it to get it out, It is going to be nasty inside the intake also so you will want to scrape off what you can and then vaccum out the intake with a shop vac too. Clean the valve off with carb cleaner after removing the orings and lead seal, you will probably need a srcub brush to clean it up good. After you see what it looks like you will know why most people put and EGR DELETE on these trucks, which for your use would be highly recommended as the valve will keep getting gummed up like this. Hopefully you also have a coolant filter on the truck too, all 6.0s need one on there to prevent the oil cooler from clogging with sand from the sand casted block.

 

It's never had a serious issue starting after hot. A time or two, it may have cranked just a hair longer than usual, but nothing crazy. I will pay more attention to this in the next couple nights to be sure. As far as the EGR idea, thank you!! That is waaayyy off base from my original thoughts and it would be a much better problem to have. I will gladly clean this out to see what happens, then proceed from there! Also thanks for the detailed instructions on how to do so. That will make it much easier for me!

As far as an EGR delete, I will do some homework and possibly add that in the coming months. And the coolant filter...If it didn't come from the factory it probably doesn't exist. This truck seems pretty stock under the hood. That's another thing I'll do some research on then see if I have it. If not, it could be added at some point. I will be flushing the coolant in a couple of weeks so that's a prime time for me to look into it!

Thanks again!!

 

Hey Bob,

Would a stuck open EGR prevent the turbo from making boost? First thing I thought when the OP described his problem was no boost pressure.

Later,

Keith

 

It will decrease boost but the bad thing is it lets alot of allready burnt gasses into the intake so the engine isn't getting enough clean air to have complete combustion, these things need gobs of air to run right.

 

One more question to anyone who can help..

When I turn the ignition to the "on" position, I hear a humm in the cab. This hum is coming from near the firewall on the driver side in the engine compartment. It almost sounds like a fuel pump priming the fuel system but the location seems wrong for that (all my experience has had fuel pumps in the tank). I was thinking maybe a fuel warmer?

So my question is, is this humm normal? Is it normal for it to last 20-30 seconds when the ignition is turned to "on"? Is it normal to hear it while I drive, over the motor and road noise? I seem to notice when the truck starts acting up, this humm seems the loudest. Thanks again guys!

 

That is normal. From what I have learned here it is the injectors going through a function check cycle that sort of gets them prepped for operation. If I am starting in cold weather, allowing the complete cycle lets me get a good start on the first try. Before I started doing that it would take me two or three tries to start in cold weather.

Later,

Keith

 

That humm is the fuel pump, the fuel pums is actually right under your seat on the frame, there is a spring upgrade for the gegulator that is mounted right on front of the upper fuel filter, they call it "The Blue Spring Upgrade" this ensures the fuel pressure stays at 60-65psi, fuel pressure below 50psi can hurt the injectors. the fuel filters shouls be changed every 10to 15k but in your situation I would not go over 10k before changing filters as you have alot of run time without mileage showing up.