yohon

OK sorry its so late of a reply but we figured it out the pre filters on these trucks has a check valve in it ( for some reason) this particular mopar filter had the check valve too far down in the filter "core" ( when the filter is properly installed a push rod touches the filter body and holds open the check valve) this caused the truck to starve for fuel ( not to mention the air leak at the front filter) i have no clue how this guy made it to work but it explains why we couldn't get a prime afterwards! Thank yall for your help

Hmm it might just be a working pump then but weak and is not able to push fuel all the way to the front fuel filter. Any clue what a healthy pressure or flow rate should be on a stock lift pump?

Agree should have been one of the first upgrades to this guy's truck. I'm just trying to get him out of the parking lot for now. Does anyone have a diagram of a common rail fuel system? I cant figure out why I have fuel at the pre filter but nothing at the filter in the engine bay. Thinking their might be a check valve or a regulator thats stuck.

That was my initial thought. Trucks on side of the road so didn't have a tester but cycled the key with the pre filter lines removed and verified in tank pump was pumping. Do these trucks have 2 lift pumps?

Need help figuring out these new fangled 6.7 a friend of mine at work asked if I could look over his truck he just got an oil change at a jiffy lube and it was running rough after. I drive a older 24v and work on it constantly so I figured they cant be too difficult or different. Check the engine bay fuel filter first thing and sure as **** no o ring on the fuel filter cap and it was insanely tight. Bought a o ring threw it in ( tightened the bolts that hold the housing to the block was missing a bolt and others were loose) crank the key over to prime and nothing. Do a little googling pull the lid of and look at level and nothing no priming. Checked the lines at the pre filter ( one under the bed) and something is pumping unhooked and verified fuel in and fuel out when key is cycled. Got copious amounts of fuel rained over me. Re installed and still no prime. I am completely lost. He drove the truck 30 min to work after the oil /filter change but when we fixed the air leak on the filter cap absolutely no prime but the lift pump is pumping? Is their a check valve suck closed or a regulator that is not letting fuel to the filter housing. Any help is appreciated Sorry forgot to mention truck in question is a 2012 2500 4x4 crew cab that has been deleted

Makes sense thank you tractorman!

Man I love the quadzilla. The fact you can do that is amazing. I sat down and had a long hard think about it and I think I'll stick with a single for now. I dont trust my transmission that much for twins or the factory heads I'd rather save my time and money and mess with water methanol and air to water intercooling.

I guess I'm not that familiar with 12vs but I thought they had basically the same injector set up with a different pop pressure and the P pump do they machine the crossover tubes?

Has anyone messed with different thickness injector washers on 24v? Doing some searching and it's a thing for 12vs but I can't find nothing on 24vs. The theory is the further in or out of the hole the injector determined where the spray pattern hit in the bowl of the piston.

I'm going to say that a 25 year relay was the cause of all of this. Truck has been running great ever since I changed the relay

Well I think it's safe to say that problem is fixed had a relay going out! thank you moparman. That pesky turbo is still haunting my marketplace feed and I just got a set of 7x.011 injectors and some 3 in pipe so I guess this still might be happening! Typically I'm guessing the exhaust manifold is flipped upside down for better clearance? Do I need to move the oil filter? I'd hate to make changing that a pain. Does the hot pipe need to be cast/heavy wall pipe? What i have is schedule 10. Did i go to big on the injectors? Thanks for reading i look forward to your replies!

That sounds electrical to me. What are you seeing for line pressure on the middle test port? When i was working on my transmission this article was gold https://mopar1973man.com/cummins/articles.html/general-cummins/85_transmission-transfer-case_85/fine-tuning-your-dodge-automatic-47rerh-series-46-and-early-48-series-similar-r614/

I always thought that was for the lift pump. Glad you said that. I swapped the vp44 relay for the wiper motor relay and so far the code has stayed cleared only had about 2 longer trips but fingers crossed that was it.

Well I think it was just timing but i put the lift pump relay in this morning. On the drive home I noted the check engine light was out. I'll try and go on some longer drives this weekend and see if it comes back.. feel like it's not gone for long...

Well then the glove box relay is going in lol.

OK so update time! Talked with Mitchell from DAP today at lunch very helpful! Vp44 i got had a new brain (PSG) rebuilt pump with a 2 year warranty but I bought it in 2022 so 3 years (man time flies) he did give me some insight on my problem Could be caused by intermittent failure of APPS and would be faster the the quad could pick up/display Didn't think it could be caused by intermittent lift pump relay if I was still seeing steady pressure. Possibly could be quadzilla connections to data link so I wanted to check that first (cheepest easiest thing first!) I'm not shure if this is the smoking gun but to me it is questionable. The middle socket is recessed/pushed in about 1/8th more then then outer 2 pins And on this conection (rather hard to see with all the dielectric grease in the way) it would appear as though the right most connector doesn't have the sping side of the pin everything passed the wiggle test at 1200 rpm though so not shure if it's worth re pinning either of these. I do have my father's 2001 24v sitting in the driveway for the forciable future and I already talked to him about using his APPS for troubleshooting so next good long trip I get I'll try and swap them out and see if I still have the issue. Did get get a good check on fuel temps 87 on the drive in 97 on the way back about 85 degrees ambient so not bad.

Will call tomorrow at lunch and see what they can do. Found someone posting about the start up rev issue in a different fourm and had the same 1689 code they traced it to the data link conection on the comp. I'll check into that and see what's what.

Well that was smart of Bosh. I will pull up fuel temps and see what I'm getting to but I don't think it's anywhere near that high. I just wish I could get this to be consistent. It's been off and on for probably 6 months.

Well though I had some good ideas for testing. Realized I could just wiggle the pump tap with a bit of throttle applied and see if it cut back to idle (doh) wasn't that. Did some spirited driving to get things hot had a camaro pull up... I don't like to push my truck it's a great way of breaking it. But today for whatever reason I let it eat and I don't know who was more suprised the camaro or me but man these ol trucks can still run! Anyways got it got got it home wiggle checked everything messed with pulling that passenger ground nothing even took a heat gun to the vp44 brain and got it a little warmer. Nothing 🙃 ill try calling DAP in the morning and see of they have any ideas. But for now I'm pretty clueless.

Ok yes we are in the main tank for the straw location! Sadly i think not because i couldn't resist pump tapping it. I will call and talk with them to confirm. ( they have been super great in the past went through 5 turbos with them)

I can't say I have checked recently and don't normally have it up 80-90 comes to mind though. I do have a good air dog on it with large line and large draw straw pressure does not drop below 15...unless I'm less then a eighth of and tank and slam on the brakes. ( not a normal occurance)

No W-T mod I wasn't sure if the battery mod was going to be permanent so I kept it pretty reversible. I essentially added a battery post to the inner fender and moved the ground clamp over to that. I may try putting a second battery back in to see if that helps. Or run the ground back to the driver battery ground. I'll have to call DAP and see but I believe I got a vp44 with a new ecu then. I distinctly rember them suggesting a slightly more expensive pump that they said they had way less returns on. Other thought could the pump tap wire be causing this? The quadzilla tap is way better they the scotch locks most fokes use but is still a tap.

Needing help with a sporadic p 1689 code. It's the only code I get and it only when I have been driving for a good bit. (Daily 20min drive to work won't trigger it) vp44 is new ish. (2 years may maybe 50k miles) was from DAP and was one with a supposedly rebuilt pump "brain" I have gone through the really helpful guide on this website. Everything tested good except the step on the ECU. Im shure it could be the ECU but want to rule everything else out. Fuel pressure looked good on the quadzilla ecu voltage looked good tps was steady. Truck drives fine but will suddenly go through a fit* and cut in and out then be done and drive fine. It has recently started to rev on start up then drop back to idle. I do have the passenger side battery removed and the ground cable grounded to the fender. (First thing i checked reads 1 ohm to the driver battery negative) the tps is a cheaper Amazon part. But has been reset and set to the proper voltage range properly. And tracks smoothly on the quadzilla so I don't think that's the issue. Really not shure what else to check on this

Only 1 code but it's a doozie. P1689. I'll do some reading up on it

That's a interesting idea of using timing to keep the boost down. All i figured was setting the max boost defuel to a safe number and calling it good. Unfortunately my truck decided I shouldn't get it. It chose yesterday to have something go out. Not not sure what yet but something was causing it to cut out hard randomly. Today's adventure will be to track down that issue.