So, this is my basic understanding of the fuel system in my truck. The lift pump is in the tank, pumps fuel through the fuel filter to the CP3. The CP3 pressurizes it to the fuel rail, fuel rail feeds the injectors. That is my own understanding, no hard facts, so correct me if I am wrong.

I have a sneaking suspicion that the lift pump is going bad, what happens is at idle it will kind of "burp" just a slight surge and go back to normal. Also I think the injectors, are making more noise than they should, (do they even make noise) because it is not the valves. I adjusted/checked them yesterday, the 1 & 2 intake rockers needed adjusting all others were within .002 either way of .010 on the intakes and within .003 up from .020 on the exhaust.

There is this constant clacking noise (I know "it's a diesel") but it goes away when I step on the go pedal, and also when the truck is coasting to a slower speed. Is it my lift pump? would a fuel air separator system help? I am all for filtration, and adding things that will increase the longevity of my rig.

If the pump goes bad will a fuel/air systems pump pick up the slack?

 

my pump just went out last thursday. i was coming off the mountain and on a down hill slope the lift pump went out. no burp no nothing just dead. i tried starting and it did but only for 2 seconds.

i turned my hey on 3 times to check codes and nothing then plug the programmer in and no codes...that was my experence left stranded on the road thank goodness i was at the bottom of the mountain for cell service

 

You should not waste your time on replacing the lift pump with OEM. the 2003 had the pump on the back of the fuel filter and the only OEM replacement is with an intank version $1200 later. Buy an Air DogII or Flow Max and install it your self. It takes about an hour and works much better.

 

i almost bought the the airdog. then i wanted fass. but my mechanic said they are both loud. kinda like a chevy silverado fuel pump.

so he talked me into a pump that pushes 120 gal an hour and is not loud.

he said if i dont like it he will tear it out replace it with a airdog or fass all at his cost. he has done this to many other people and still no one has came back. so im taking his word.

i do know the fass and airdog is what 160 gal and hour but with my little mods i will never need that much. im not going to kick myself in the butt casue his warranty deal is one i cant pass on

 

So what you are saying is just leave the pump in the tank and place air dog or other pump on fuel line. Leaving non working oem pump in tank will have no ill effects?

 

If you leave the pump in the tank, which you need to do because it also has the gauge sending unit with it, you have to add a draw straw kit so your new pump inst trying to suck thru a dead pump. i would never ever put a pump in a tank. To difficult to get to. Always remote mount it.

To the original poster....do you have a fuel pressure gauge? if not, you'll never know what's really going on. letting a pump flow into a jug while holding a stopwatch will also tell you nothing. Free flow versus flow under pressure is two very different situations.