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Losing Prime and my F#%ing Mind!

21K views 50 replies 14 participants last post by  long-time-dmax 
#1 · (Edited)
I have a 2005 LLY tuned by Idaho Rob with Nicktane adapter and PPE race plug. For the past several months, every once in a great while my truck would lose prime and chalked it up to the fuel filter head as it became more frequent. Just replaced all 8 injectors and rebuilt the fuel filter head while i was at it, now the problem has progressively gotten worse. It has gotten to the point where I have had the fuel filter head off about 5 times looking for stuff, and I just said heck with it and put a brand new fuel filter head on, along with my nicktane adapter. I just replaced the FICM lines from the fuel filter head and no change. Does it tank empty, does it tank full. Now it is losing prime in less than 5 minutes of sitting, when I take the fuel filter off it is empty (not sure if this helps). I have to pump it up everytime I get out of it or it will just run then die. Futhermore, a P1093 has progressively gotten worse, used to only do it when I tow and now it does it when I climb mountains on the interstate. It seemed to do this a lot more when the truck was below 1/4 tank the other day. Also, the max rail pressure I have ever seen on my CTS is 20.4Kpsi, I have not done an actual vs commanded pressure check yet. No leaks at Schrader valve that I could see, only other possibility is potentially the rubber portion of the hard line coming in, but will the rubber portion of the return hard line cause an issue too? I'm to the point where I am about to go have the Chevy garage do I total fuel system check, CP3, return rates, the whole 9 yards. Gonna do a fuel filter change even though it isn't that old just to completely eliminate it from the list. Any ideas?
 
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#3 ·
I don't have a stock filter, but I am thinking about bypassing the filter by connecting the 2 FICM lines together and just letting it run enough to make sure it is primed. Then, I was going to leave it sit and check it the next morning and if it didn't lose prime then there is something wrong with the filter head combination.
 
#4 ·
I would not rule out the filter head as the culprit even if it was rebuilt.
 
#5 ·
Yeah, that is what I figured. I rebuilt my original and the pump didn't feel quite right, so I replaced it with a new one from gm. There is no difference between the 2, same exact symtoms.
 
#7 ·
No I haven't. As stated, I don't have a stock filter and can't afford to spend $50 to try, especially if it happens to not be the problem. Thanks for the input though. The more thinking I do, the more I feel as if it is the rubber portions of the hard lines coming from the tank. They are next on the list. I had found a post that had the EXACT same symptoms as I am experiencing, with the same equipment but it abruptly ended with no conclusion. dang....
 
#9 · (Edited)
just something free to try....I had an issue losing prime a couple years ago. It ended up being a pinhole right at the quick connect on the feed line by the fuel cooler. I wrapped a rag around my air hose and stuck it in the tank and had someone bump it a few times to put air in the system. Immediately saw the drip. Might be something to try and like I say.....it's free.
fwiw pretty sure I've read before about people having issues with the nicktane adapters so I would make sure to check that real good too.
 
#11 ·
As mentioned, might be the adapter, o ring on filter??? Run down to auto store, pick up a cheap filter to put on in place of adapter... only way to rule it out.
 
#10 ·
Your new filter head didn't come with a filter?
 
#12 ·
Update. Put a new Donaldson filter on and it solved the problem...for a week. Back to square one, every once in a while it loses prime, sometimes it doesn't. And yes, I just bought a new fuel filter head with no filter, didn't need one. Next thing for me to tackle is the hard lines where they turn to rubber, going to deal with that hopefully tonight. Still throwing a p1093 and I need to do some data logging. I'm going to try pressurizing the tank also, but I've done come to the realization that it is either a lift pump or sell the truck, and I'm leaning toward the latter.
 
#13 ·
Had similar issue with mine when I installed Nicktane adapter, no issues with CAT filter, but then switched to Donaldson and had all kinds of issues, usually after truck had been ran got warm and then shut off. My issue ended up being I was trying to use small thin oring that went on the adapter thrads whete filter screws on when I should of been using the thick oring that came with the Donaldson filter which looked more like a cutoff ftom a hose. Started using right oring and no more issues for me.
 
#14 ·
That's what I was hoping for, but I think I have a collection of issues that is causing me fits. The truck smokes after new injectors, especially after it sits and idles for a brief period. If I rev it, it blows a big cloud of greyish/purple smoke, then once that clears it will turn darker as signs of unburnt fuel. My truck is an ABSOLUTE PITA to drive. LLY ZF6, no low end power whatsoever until you get to about 1200 rpms and the gas pedal is downright awful. I've done some data logging today because I called ATP trucks last month and told them how unhappy I was about how my truck ran after they tuned it. For about a year I attributed it to injectors, fuel filters, etc etc trying to shrug it off. Now it seems I have replaced about everything in my fuel system EXCEPT the CP3 and still have power and priming issues. I actually started advertising my ZF6 I dearly would die for because I am past the point of frustrated with this damn thing!
 
#15 ·
Me same almost, 30% will idle down & shut off, mostly if warm out after start. If I rev just after start will stay running fine, but embarrassing in front of my Dodge friends, been meaning to get rid of them anyway. Pressurize the tank?
 
#16 ·
Update:
Changed the rubber 1/2" line right in front of the glow plug controller and it seems to have helped but it still isnot perfecr. You can tell when I start it that it wants to die down a few rpms then picks itself back up then is fine. Starts OK but just something fishy, also telling me I need to change the fuel filter every time I start my truck.
 
#17 ·
I had this problem and fought it for thousands of miles. Started right after I installed a Nicktane adapter and Donaldson filter. I bought this truck new on 3/23/2002 and have put 350k miles on it. NEVER had this problem before I added the adapter and filter.

2 questions: When you lose prime, can you pump it back up w/o loosening the bleeder screw? Does it happen more frequently when you tow?

I finally got mine fixed by installing a lift pump. I wrote it off to the Donaldson being more restrictive but a member on this forum says the Donaldson flows better than OEM. I don't have a clue but I know what solved the problem!! My theory was that the new filter was more restrictive and not allowing enough flow to keep the filter full. I was always able to pump the primer w/o opening the bleed screw and get going again. That meant to me that I was actually not leaking air into the system and the 2 pump/filter head rebuilds I did were useless. What appeared to be happening was that I was actually pulling a vacuum in the filter with the CP3 because something was not allowing enough fuel to flow thru the system. It would happen a lot more than it sounds like it is to you - especially when towing. Which makes sense - using more fuel while towing.

Anyway, has not happened once since I put the lift pump on there well over a year ago.

Was also told by someone on this site way more knowledgeable than me that one possibility is that I left the O-ring on the Nictane adapter. The O-ring he's talking about comes on the threaded tube you screw the filter onto. You're supposed to remove that O-ring and replace it with the flat, rubber washer that comes with each Donaldson filter. I just learned this a week ago and have not ha a chance to see if I did that yet.
 
#18 ·
This may be dumb but im only asking because it hasn't been mentioned and my truck did the same thing with my nictane adapter, did you remove the check ball from the filter head assembly? and X2 that donaldsons are restrictive, the first time i used a donaldson w/s i was dropping fuel pressure to almost 0 whenever I hit the go pedal, switched it with a cat w/s and it was good.
 
#20 ·
Going to have to sub in on this one.. I've had the same problem for almost a year and my efforts have gotten me nowhere. Mine only seems to die out after running for quite a while and getting really warm (say 100-200KM trip in warm weather), upon re-starting it would die sometimes instantly and sometimes after driving 100 yards. Then this winter it would die when cold just after starting..

I had this issue once pre-install of nicktane & donaldson. Steps below are what i've done so far..

1-Re-build filter head and installed nicktane & donaldson.
2-Removed nicktane/donaldson, and installed new fuel filter head w/ stock filter
3-Pressurized fuel tank and checked for leaks, none found
4-Found small leak (bubbles in schrader valve cap) on occasion. Installed O-ring into cap so it cannot breathe outside air anymore
5-Traced all rubber lines for cracks/wearing, couldn't find any

After each step it's still intermittently shutting off when it wants to, but not all the time. Occasionally now after starting the idle will surge up and down for 5 seconds and then level out. I'm at about the same place of almost ready to pay out of pocket for dealer to check full fuel system unfortunately.

Sorry I'm of no help really
 
#22 ·
Just a WAG here, but maybe your CP3 pump is weak? Do you have a lift pump? Sure fixed my problem.

Since yours only does it hot, what's the chances it's vapor lock? Never really heard of vapor lock on a diesel though.

How about a weak CP3 pump that get weaker when it's hot?
 
#21 ·
As for my truck, I had a wix filter where I accidentally left that cat o ring on and I thought that was all my problems and it would be solved. I can pump mine without loosening the bleeder screw and it primes right up. My rail pressure is fairly good according to my edge cts, commanded vs actual is real close until WoT, then commanded is 23k and actual creeps up starting at 20.5 until about 22.5. And yes, I throw a P1093 every time I tow, but haven't towed since I changed the line on the quick connect hardline. I'd say lift pump is the answer. Did your truck come alive after adding a lift pump when you were experiencing these issues? Mine just seems to want to stall in low rpms
 
#30 ·
After adding the lift pump I noticed a couple of things. Wouldn't really say it came alive though. Although it does run good now, just didn't notice any night / day differences.

Noticed that using the Donaldsons I can tell when they start to clog up. Pulled my 16' x 7' cargo trailer bout 800 miles and the filter was so clogged up I could barely make 70 mph. It was really noticeable pulling the trailer and I could feel it not towing too, but not near as much. Changed filter when I got back home and it was good to go. NEVER had that happen using the OEM filters. I've noticed several this several other times too. I change oil and fuel filters every 10k miles. Several times when up around 8-9k miles on the filter I can feel the filter starting clog.


Not really something I noticed but nice just the same. With the lift pump, I no longer have to pump the new filter full when I change it. Just turn the key on and crack the bleeder and wait 30 seconds or so.

I still need to check my O-ring. It is very possible I did not do swap them.. I'll most likely wait till I change filters again in a few months since it makes such a mess. For now, it runs fine.
 
#23 ·
May be FPR going bad, or a short in the harness. The ECM cuts injection power and rail pressure when P1093 sets bc its sensing a signal of more than 175 mpa from the fpr.
 
#25 ·
disregard just read your previous post.
 
#26 ·
how big is the tune your running from idaho rob?
 
#27 ·
My tunes I run constantly are optimized stock and 30hp heavy tow
 
#32 ·
Update: replaced feed line per tsb, no change. Truck is constantly telling me to change fuel filter and is throwing P1093 as soon as I put 500 lbs behind it. Injection pump readings look good. I'm stumped. Any more ideas?
 
#33 ·
had a tech 2 put on it yet?
 
#34 ·
Got an appointment on the 10th to see what's going on
 
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