Gitch

No its all good. Thanks for sharing. Any other ideas from other people are always good. Still waiting on my buddy to get the truck back to try the fca. After that if that didnt take care of it im gonna route a new return line since its cheap and wouldnt hurt anything. If thats not it im gonna suspect cp3 and try and have ats in denver to determine thats the problem before i commit to a new one.

I have only had this truck for a month or so and knew nothing about diesels. but def got a crash course so far in learning haha

mq105

Are you positive that your problem is related to the level in the tank? If it is, then FCA, CP3, etc. can't be the cause because they are not related to fuel level. The only thing it could be is something physically/mechanically affected by the level being high, or something electrical that is affected by the level being high.
I can't think of anything that fits those criteria, unless there is a short in the gauge sender wires that affects the fuel pump power circuit. If that were the case, it would be reflected in FP and RP reading.

Start from the beginning: How long have you had the truck, and did it run properly when you got it? When did the problem start? Did you have any injector or other work done right before the problem started? You replaced the injectors and LP because of this problem?

Gitch

Yes 100% of the time the fuel level is low it runs great. Engine light wont even come on most the time.

WHen i got the truck it ran pretty bad. Took a while to start (multiple Cranks) black smoke etc. All the symtoms of bad injectors. So i replaced them ALL with SS bodies. A mechanic from ATS replaced them. Truck ran much better. Starts up everytime right away.


But still had the codes. I read alot more..researched etc Decided to check the rail pressures. Had my wife take it to a diesel shop to get them tested. They tested Good. Put the tank was around 1/4. At the time i didnt know that had any correlation. So they said the truck runs great and like its supposed to.

I got back from the field (army) took it for a drive.. Put fuel in it and ran like booty. Was annoyed outta my mind.

So after Knew that the truck acted differently dependent on the fuel level. Well the only thing in the tank is the lift pump. So i figured... might as well get an airdog and lengthen the injectors life. So i put that in. Ran much smoother but still had the code and still is affected on the fuel level.

So my thought was return line. Because there was a thread i read about that causing problems... let me find it quick.
http://www.cumminsforum.com/forum/98...ml#post3648654

Different year but i thought the concept might be the same.

So im still waiting on my buddy to check the fca.

Then after that ill change the return line..then after that ill get some help from ATS on check cp3.

anyways...i hope that makes sense

mq105

I don't understand. Below 1/4 tank you still get a CEL on occasion, but 100% of the time it runs great? I don't see how it can be great and have a CEL.
It sounds like you still have the problem when the fuel level is low.

Is it possible that the truck is not fully up to temp when you are low on fuel, then fully warm when you fill up and have the problem? In other words, has the truck been up to full operating temperature with below 1/4 tank, and not triggered a CEL? Or, the opposite: have you had the problem with a full tank and the truck not up to temp?

It sounds like it could be a loose connector tube(s).

SpeedyWS6

I guess it's possible that if the return line was clogged it could cause cavitation in both pumps, but I can't see the return line being effected by fuel level. I would be pulling the tank down for inspection again if I was working on it. It has to be in the tank if it is effected by fuel level.

Gitch

Well i just made a 1200 mile trip from colorado to michigan like this. Every fill up was the same. It was running at operating temperature pretty much the whole time.

Yes when it gets down to 1/4 tank it runs great. Engine light will stay on unless i clear the code with a code reader from a-zone or something. And will stay off everytime until i fill up.

SOMETIMES when i get down to a quarter tank...and shut it off at night...come back in the morning when its been setting all night ill start it up with no engine light. Even if it was on when i turned it off the night before.

So yea...this is probably the most frustrating thing i have delt with in a while.

I will check the tubes when i get back home. when i get back to the main tools.

Gitch

Also just swapped the fca and made no difference.

mq105

If it truly is related to the fuel level, then it isn't the crossover tubes.
How is the power run to the fuel pump? Factory harness? Maybe you have some sort of short between the level sender and something that is affecting the engine. Maybe disconnect the level sender wires as a test.
I would drop the tank and check the module and hoses for problems. Also check the orientation of the level sender arm. Make sure when it moves up as the fuel level rises is isn't hitting or blocking something. (Although what, I don't know.)
This is definitely a new one.

oldblu

glitch, man i thought i had trouble figuring this deal out, yours sounds horrible compared to mine. what i can tell you bout mine is that i've owned the truck since new, did all the work on modding it myself, and this p0148 has been around for probably 6 months or so now this makes, i do know that it had done it before the airdog install, i know that when your check engine light comes on it will go off after 6 key cycles i believe, hence when you shut it off the cel is still on and start it back up it will go off. I was really hoping that when you swapped fca that it would fix this mystery but since it hasn't we'll keep pondering ideas and hoping the 0148 gremlins get out of our trucks..

Gitch

I really appreciate the help so far guys. The truck is sitting about a quarter tank right now and the truck is running real good. haha

As usual.

Im gonna try tomorrow night to get the truck in my buddies shop on his lift to pull the tank again and look at the sender. Im also gonna try disconnecting the harness as well. Never know with this stuff.

I actually thought about the fuel level arm AFTER i put it back together. like maybe it was somehow pinching the return tube in the tank wheni t was full. but never even though while i was installing the airdog since i thought thats what the problem was at the time.

So atleast one more possible issue is crossed off (fca)

oldblu

Maybe you could pull the bed instead o dropping the tank? That way you could get a better look at how the module and sender is going back in the tank, that's how did mine took 2 guts prob 30 min and it's off.. As
long as u have a way to pick the bed it's easy, don't know what type of lift you have access to but mayb you could use it?

Gitch

Well taking the tank out is actually pretty easy. Its 2 nuts and just release the straps. I did it in my driveway the first time. But it had 17 gallons in it lol

This time im going to my buddies shop, lifting the truck up and using his transmission lift to lower it down. Should be pretty easy.

Gonna pull the sender and play with how the fill lever works to see if thats the problem or not. if i dont notice anything there im gonna fab up my own return line. Maybe put another homemade short draw straw towards the front of the tank to keep it away from the pick up for any issues like foamin etc from flowing back in the tank.

Or maybe just run it back to the neck where you fill up at like the airdog does.

Its like a dollar a foot for 5/16 fuel line rubber hose at advance auto.

At the filter in the front of the truck its a quick connect attachement. So ill just disconnect the stock one. Run the new line next to it and have it dump back into the tank somehow with no restrictions anywhere. Put the tank back on and give it a test drive after fill up.

Only real investment is time. But at this point its better than money. Gotta do something on my block leave haha

Gitch

So tonight.. 1/4 tank. Truck warmed up.. Running like booty. Hmmm after a little while it ran well again. But not right away. So i dont get it.

I reallly hate this truck. First diesel probably last one too. Atleast til after deployment.

Anyways. Im lookin into finding a cp3. Can you swap these pretty easy to check them out if they are bad or not? Or is that a bad idea?

I am loosing more hair than id like to admit.

AH64ID

you need to verify rail psi when its running crappy.

Gitch

yeah ill call around for a shop that can test the rail pressures tomorrow. FIll it up and drop if off, maybe figure it out.

IF that's not right i assume its cp3? because the lift pump is brand new.