repeat #4,#6 inj failure

[frd senior master tech]

this 6.0 has had 3 sets of injectors for cylinders 4 and 6. i put the last two injectors in and found that the hold downs were streatched. i called the hotline and was told to replace all 4 injectors in and all 4 hold downs. i did that and changed the oil. the vech is now back with a dead hole #6. #4 is skipping intermittantly. i did a fuel pressure test and relative compression test. compression was green across the board and fuel pressure was 50psi under load. i checked the oil supply rail for any debrit from the hp pump and found none. any suggestions would be great. the injector gaskets, o-rings and clips are all there and in good shape.

[Mekanik]

I see a lot of aft. axle trucks with failed injectors. The tank is usally contaminated and it seems that the engine has to run for a while before fuel pressure will drop. I usally let them idle for a coulpe of hours and then drive them and see the fuel pressure drop. I hope this helps.

[Keith Browning]

Was there any carbon between the lower fuel o-ring and the copper seal that would indicate combustion leaking past the seal into the injector?

 

A short time ago I took over a job for a co-worker that kept blowing injector #2. Three injectors went into the truck before I got it. I suspected that the injector sleeve was distorted from the original failed injector. Replaced the sleeve and the truck has not been back.

 

... just another idea.

[frd senior master tech]

not to sure why i never thought of that cylinder sleeve. i will check that tomarrow. i will also let the vech run and check the fuel pressure. i will let you know tomarrow. any other ideas keep them comming.