Low Fuel rail pressure

[mississippismitty]

Had fuel in the oil and major smoke out the pipe so replaced the injectors and all was well, I thought. running down the road it would loose power and started getting codes of low fuel rail pressure and EGR position. Replaced the EGR and that code went away but still had the loss of power and if you kept your foot in it, it would die and either cranke for a while to have it start again or pump the primer on the filter to harden the system up and it would fire right up. Figured I had a clogged fuel filter so I replaced the filter but no change. After some observation I saw that the primer was being sucked down. I'm thinking of disconnecting the fuel lines and blowing back to the tank. Any cautions or recomendations?

[DmaxMaverick]

Welcome aboard!

Definitely sounds like you have a significant restriction between the filter and tank pick-up. Anything you can "blow back" through the lines would indicate a major contamination issue. Otherwise, I'd suspect a collapsed hose or pinched line, which should be obvious with a quick inspection. I suggest taking the filter inlet line loose, route it to a container, and "push" some fuel from the tank to the container (low pressure shop air works well), for fuel inspection and/or testing. You may have a biological (algae) issue at work. With what you've seen so far, I wouldn't suspect a problem with the system between the filter and pump.

[Heartbeat Hauler]

When you replaced your injectors, did you also replace the injector lines? They can also be a source of contamination and really muck a good set of injectors. I don't think this would contribute to your loss of prime though.

I kinda have the philosophy that the culprit is usually the last (or related to) thing you did prior to the problem.

[Kennedy]

Let's start from square one:

1) What year/engine is this? Sounds like LB7 with CA emissions, but...

2) What did you use for injectors when you replaced them?


Definitely sounds like a restriction. A lift pump and repaired supply would be highly recommended. I've heard a fair number of cases where the tank was removed and reinstalled pinching the supply line tight and flat. Also some of the early pickups had a very fine mesh screen that could clog if you had bugs in the tank.

[mississippismitty]

It is the 2003 LB7 but not the CA model. I replaced the injectors with GM factory injectors and while I had the lines out I cleaned them and they where nice and shinney going back in.

Well here is the update. I pulled the lines apart and blew from the connection under the master cylinder to the filter connection and it was clear. I tried to press the tank and check flow from the tank to the connections under the MS but couldnt get fuel to flow. I went ahead and blew back towards the tank and you could hear a little flow and then all of a sudden heard a thud in the tank and air flow rate changed considerabley.
This weekend I pulled the tank and removed the pickup unit from the tank and found a globual of crap in the fuel pick up plastic screen area and the plastic screen was at least 3/4 clogged with the goo. Cleaned out the pickup and then wiped out the bottom of the tank but found nothing in the tank itself only in the pickup. Reinstalled and now runs like the stripped A$$ ape I knew it could.
So not sure if it was just from it sitting about a month while I got to replacing the injectors or just an unfortunate thing that happned.
Anyway works great

[More Power]

Have you ever had water in the fuel filter assembly? Bio contamination usually accompanies some amount of water.

Jim

[mississippismitty]

If there was water it wasnt enough to cause the sensor to detect and when I replaced the injectors I had to drain the filter to get it out of the way and no apparent water came out then either. The funny thing is that the truck has always had a little white smoke and we were on a cross country trip when it decided to start bellowing white smoke and also filling the crankcase. I changed the oil when the pressure started to drop after figuring out what had happned. We drove another 600 miles to get to our destination before parking it, we were pulling a 32 foot 5th wheel and other than the smoke and fuel in the oil, there was no noticable change in the power.
Talking to a local mechanic he said the EGR was probably crap for a while and the extra fuel going out the exhaust sealed it's fate but there was never any indication of fuel starvation prior to post injector replacement so not sure if there was crap inthe return circuit and once the repair happned it blew it in the tank and then it became a problem. It wasn't an immediate hard core problem but happned over about a weeks time.