New pump, has pressure wont start

Radio · Apr 27, 2014

Ok so long story short, shop x got a customer with a 2008 6.4 that died and would not start. Shop x replaced the low pressure pump with no luck. Shop x does not do diesel work so they talked my buddy into working on it.

When we first started on it, we were getting plenty of lift pump pressure (like 30psi if i remember right), but we only showed that 30 psi for rail pressure. We changed out the high pressure pump and now we get up to 7000psi rail pressure while cranking but it will not even try to fire. We have bled the fuel system multiple times at the fuel cooler. There are no codes. We've cranked on this thing for hours with nothing.

We're just wondering if there is anything we have not thought of that you guys might suggest.

Also, do these trucks have a chiped key in them that would prevent them from starting if it was not the correct or a spair key?

G Racing · Apr 27, 2014

If you have a bad key it won't turn over. I assume you pulled the cab to replace the hpfp? Did you get all the harness, grounds and hot wires hooked back up? I would tend to believe that the injectors are not firing. But it's just a guess. Do you have engine oil pressure?

dsberman94 · Apr 27, 2014

I'm going to suggest just going through and making sure all wiring connections have been hooked back up. A couple are easy to miss if you don't get them before reinstalling certain items.

Radio · Apr 27, 2014

We changed the pump cab on. The injectors will pass a buzz test. As far as oil pressure, we are getting the oil light on the dash. I dont know why, but the modis we are using does not show oil pressure. Oil level is fine. I guess we could throw a mechanical guage on and see. Will it not start if it does not see oil pressure?

Radio · Apr 27, 2014

We're going to rip the old pump apart and see if it was mechanically failed and sent material to the injectors.

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Dzchey21 · Apr 27, 2014

what is injector pw while cranking?

Radio · Apr 27, 2014

It was around 1.2-1.3 if I remember right. My buddy tore the pump down and there was some rust and a little metal in it. Looks like we're doing injectors, lines, and rails next.

Dzchey21 · Apr 27, 2014

yeah if its comanding pulse width then it should be starting

Web06 ran into this same deal awhile back and ended up having to put in a full set of injectors to get it to run. must rust the pintles or something

Radio · Apr 27, 2014

Yeah the owner gave the go to put injectors in but we're waiting till we see cash for the work already done.

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Radio · May 28, 2014

Just realized I never gave an update on this.

Installed new injectors, rails, and lines. Truck runs like new again.

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Dzchey21 · May 29, 2014

thats what i figured, there is a truck local thats been to a local chop shop and they cant get it running im thinking that this might be the issue on that truck as well, id like to see what the inside of an injector from a truck that doesn run.

Radio · May 29, 2014

This one had so much water run through it, even the injector tips had rust on them.

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DEEZUZ · May 29, 2014

I hate to say this, and I hope it doesnt happen in your case, but it probably will. But dont be surprised when this truck comes back to you in the future with the same issue. Without starting from the tank,a nd working your way up, replacing, cleaning, flushing, etc, that debris is still in there and it will take out the pump and injectors AGAIN. There are a few items that NEED to be replaced after a HPFP and.or injector job. Things that are not flushable, like the oil cooler, fuel pump, secondary fuel filter housing, MUST be replaced. The pick-up, tank, lines, etc can be cleaned and flushed out.

Did you back flush the heads through the return ports before replacing the injectors?