Just joined today, I have a 2003 550 7.3. New HPOP, 3 new injectors, new seals on others, new fuel pressure regulator, new fuel pump, sending unit mod to eliminate filters. 733 HPOP pressure, 65 fuel pressure at idle. Truck runs out of fuel pressure after its warmed up and driven about 20 miles. Haven't checked voltage at pump while driving. Could use some help I had taken it to a seasoned tech of 20 years and he had replaced HPOP and 2 injectors and it does start better but problem is still there.

 

This can be bad injector O-rings or the need for a Hutch mod. I don't know what a "sending unit mod" is, but I wonder if you still have pickup screens or a pre-pump fuel strainer.

 

Yes I removed the screens from inside the tank and did the hutch mod. I also replaced all injector o-rings.

 

Forgot to mention new ipr and icp also

 

Welcome to the board Snowman,
Was the truck doing any of this before the work was done?

Did you notice any debris in the tank while you were in there? Is it a metal tank? Did you add an in line filter of some kind to replace the tank screens?

Where are you measuring fuel pressure, post filter?

Do you still have the old fuel pressure regulator and could you stick it in just to make sure you didn't get a bad one? Bad parts out of stock are not the norm but not that rare.

Paul

 

No I couldn't see if there was any debries in tank and I have ordered a new plastic one. No filter in tank, and measuring fuel pressure in bowl using the method of installing a Schrader valve in cap, so that would be post filter pressure. I have thrown the older pressure regulator away so I can't put it back in to try. Have you known of the fuel pump relays to get warm and then not work after a duration of run time? This truck will give a 1211 code when the engine looses power, you can pull off the side of the road and reset the computer and will run. But yesterday was different it didn't want to run afterwards and it hasn't kicked out the code. Also can a cmp do this? It is 7 years old. It seems to cruise ok until you pull wot. I really appreciate all of your help.

 

We are talking two different issues here - the 1211 and the low fuel pressure.

Since you have a metal tank, it would be useful for you to know the liner inside has been sloughing on other trucks in recent years - this would clog either the pre-pump strainer or the pump.

Just for funny - say you have a fuel additive foil seal sloshing around in the tank. If that debris were to get sucked up into the pickup screen, you would lose fuel pressure - then it would fall away and fuel pressure would return when you cycled the power.

Another member recently had a fuel pump fail right out of the box - on his plow truck just before Snowzilla. Is the pump OEM?

The 1211 could be from a hot tune - what are you running?

 

No tuner just stock, I definitely agree on the tank as far as it delaminating. I will pull sending unit shortly and really try to examine the tank. It just seems so directly to run time. I had read in a forum that the high or low icp pressure can be related to lack of fuel pressure. I doubt it's the engine oil but I may just change it and filter today to eliminate that as a possibility. Just as a side note when I pulled the oem intank filters they were clean and this has a new oem pump.

 

Would you recommend checking fuel pressure right next to pump to determine flow?

 

Actually, low fuel pressure often causes a P1211 to be thrown.

 

Ok I thought I had read that. Thanks

 

Thank you for the correction - it's always best to get more input.

It's possible this is not a matter of time per say - but more a matter of picking something up in the tank and repeatedly blocking the intake. Turning the engine off removes the suction and the debris falls away until the next time. That and bad pump out of the box are two things that pop high on my thinking process.

 

+1 on the drop the tank and inspect for debris and/or sloughing off of the liner of the metal tank. I am the one that had a bad pump right out of the box 2 weeks ago after the installation of the Racor PS120 pictured above, did my original 192K miler in. It had us scratching our heads for days leading up to replacing it with a 2nd new one and she fired right up. It could be that, but I think more than likely we are looking at debris/restriction somewhere. I would also recommend blowing compressed air back through the lines into the tank and seeing if that helps. If it does, then that is a good indication of debris being the issue.

 

I agree, I just modified a 3/8 inline fuel filter and opened up the end to allow more surface area for draw. I will know in a little while.

 

P.S.- you are new so you won't be able to post pics directly until you have 25 posts(I think) so if you get a chance, take pics of the inside of the tank and either start a photobucket account, or something similar, where you can host pics and directly copy and paste the HTML code and post here so we can see, or email one of us and we can do it for you for the sake of posterity on this thread.