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Discussion Starter · #1 ·
Issue
Hello, I have a 2005 LLY, it is studded, deleted with an older edge racing tuner, EGR deleted, has all new injectors, new cp3, race fuel plug, and all new hoses on the fuel side and a FASS 150. 90% of work has been completed in the last 2 years by myself and a friend who's a mechanic. I am just a self taught wrench Turner

My problem started about 6 months ago pulling a small trailer with a UTV on it. Driving 70 mph, I noticed the truck was not pulling up an overpass like usual, looked at my programmer and my DFRP was 22k VS FRP which was at 7k. Over the course of the drive home it did the same thing one or two more times. Now 6 months later it will do it every time I accelerate with any boost and will not build pressure above 17k on it's own. After it gets to 17k psi or so it immediately drops FRP to 3 or 4 k and I let off the throttle. I have checked fuel lines till I'm cross eyed, changed the tune, drove it on stock setting for weeks and have changed fuel filters and water separators twice.

A mechanics shop has it right now and they have ran diagnostics on the injectors, FASS, CP3 and all come back normal.

The mechanic told me yesterday he can command 27,000 psi to the pump and it will maintain it no problem. Return fuel rates from injectors are normal and he can not find any fuel leaks anywhere.

Injectors are stock from Diesel Logic
CP3 is reman from Bosch

Any help is greatly appreciated.

Cdieter
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Sep 09, 2019 · #2
Hey guys any help is appreciated. The truck has been in the shop over a month with no end in site. I did the head job, installed the cp3 and installed the fass system. Still trying to figure out what would cause a low fuel pressure issue at higher power demands.
Jberger93
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Join: Apr 2019
Posts: 278
Pittsburgh Pa

Sep 09, 2019 · #3
I would think it has to be an air leak . Have you pulled the gas tank down recently ? I ask because I had similar issues and couldn’t find a leak for the life of me . Then when I pulled the tank off , the fuel sending unit was leaking . It looks as if it is normally soldered on and the solder broke . Once I replaced it with a new one , problem solved !
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Last edited by Jberger93 - Sep 09, 2019
Cdieter
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Sep 09, 2019 · #4
I did not pull the tank. The mechanic thought the fuel deliver was restricted somehow so he pulled the tank and removed part of the sending unit I think ? It has a fass 150 installed. I will relay to him the comment. Thank you for your help.

Cdieter
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Join: Sep 2019
Posts: 4

2 days ago · #5
Well so far not good. I've been on orders for the military and out of town for the last 3 weeks. My mechanic still hasn't figured it out. At this point I'm ready to tear it apart myself and change the cp3. Any other ideas ? I'm all ears. Not sure what to do ..... I've got over 13 grand in it after purchase price now....cant really sell it as is tho .... any help is greatly appreciated
 

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Discussion Starter · #2 ·
Update on the problem. I got the truck back from my mechanic. He hadn't worked on it in over a month so I went out, charged the batteries.....barely got it to start and she ran great for almost 3 days. Mainly because I was scared to get into it too far. Once I finally did at about 10 lbs of boost and 3/4 throttle the same problem came back. Just not as prominently.


The guy I had working on it did say he dropped the fuel tank and removed part of the sending unit that restricting the flow. Other than that we still do not know what else to try. It's not throwing any codes, the fuel filter and water sperator have been changed twice.


I think I'll try replacing the FPR and see where that gets me. One question, could the fuel pressure sensors on the rails cause a false reading and cause the cp3 to slowly drop the pressure ?

As always any help is greatly appreciated.
 
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