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Discussion Starter #1
Hi folks. Been cruising around the site for a while but never posted. Lots of useful info from you guys.

I've been getting code 0093 when pulling a heavy load. Engine goes limp till I shut it down and restart.

I found some info on shimming the FPR spring after power upgrades but couldn't find any specifics. I finally decided to try to shim but bought a new valve from the dealer beforehand just in case the shim job looked fishy. After tearing into it, I found conflicting info on shim thicknesses to use so I opted to just use the replacement valve; thinking that w/115k miles the valve could be a little weak.

Long story short, still throwing codes even with no extra power tuning.

Any thoughts?

2001 Duramax, 3500 GMC, straight stock except Hypertech sometimes.

Thanks
 

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strokenasty
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when is the last time you changed the fuel filter. sounds like that is the problem
 

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Discussion Starter #3
stroke250 said:
when is the last time you changed the fuel filter. sounds like that is the problem
A filter change was the first thing I tried. However, I've been living with the prob for a while (no idea how many miles) so it might be time for another. I'll try it.

Thanks, Steve
 

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start with the filter then if that doesnt fix the problem you need to see what your rail pressure is you can do this either at the dealer if you know a tech they can put a pressure guage on in to see what your accutal rail pressure is. or if you know somebody with EFI Live you can have them do some logging. this will be the only way to start to figure out what the problem is with the surging. now i will say that my truck surges when its cold out and my reasoning is that the fuel is thicker and not allowing it to flow as easily but once its warm everything is fine. i think my problem is leading toward a prematurly worn CP3. you might also have this issue.

Jared
 

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Discussion Starter #5
Jared Duramax said:
start with the filter then if that doesnt fix the problem you need to see what your rail pressure is you can do this either at the dealer if you know a tech they can put a pressure guage on in to see what your accutal rail pressure is. or if you know somebody with EFI Live you can have them do some logging. this will be the only way to start to figure out what the problem is with the surging. now i will say that my truck surges when its cold out and my reasoning is that the fuel is thicker and not allowing it to flow as easily but once its warm everything is fine. i think my problem is leading toward a prematurly worn CP3. you might also have this issue.

Jared
I changed the filter yesterday after hunting Easter Eggs; maybe just a little better. I hooked to the tractor and ran up the road about fifteen miles or so and it went limp three times. I really had to hoss it to get the code but it's still there (without the HP turned up). Before I changed the FPRV the engine would 'hunt' when idling; it's smooth now so I'm confident that the valve must have been at least part of the problem.
I noticed in your sig. that you have EFI live. Can you program around this kind of issue with that setup? CP3? What's that?

Thanks, Steve
 

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BUG JUICER and
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Shim it. EFIlive is the best way to log the pressure reduction if the FPRV is popping, it likely is.
 

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killerbee said:
Shim it. EFIlive is the best way to log the pressure reduction if the FPRV is popping, it likely is.
We cant shim it we have LB7 motors so we either have to replace it or tune around it.

With EFI live you can tune around the issue to a certain extent but you will most likly need hard parts to solve this like a lift pump and stock idling tables or a new FPRV, or a CP3. the CP3 is the pump that pressurizes the fuel before it goes into the common rail. latly i have been messing with my idling tables and the lift pump to smooth out my idle.

Jared
 

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Sthorpe45 said:
I changed the filter yesterday after hunting Easter Eggs; maybe just a little better. I hooked to the tractor and ran up the road about fifteen miles or so and it went limp three times. I really had to hoss it to get the code but it's still there (without the HP turned up). Before I changed the FPRV the engine would 'hunt' when idling; it's smooth now so I'm confident that the valve must have been at least part of the problem.
I noticed in your sig. that you have EFI live. Can you program around this kind of issue with that setup? CP3? What's that?

Thanks, Steve
From the sounds of this i would try checking the mesh screen in the tank on the pick up unit. this maybe dirty causing you issues. if you go this rought i would reccomend installing a billet pick up kit which allows more fuel in to the motor. all the lines after the tank are 1/2 in but the stock pick up is 3/8 in this causes a lot of work that the CP3 dosent need to go through. if you do all of this and it still doesnt work i dont know what to tell you.:shrug:

Jared
 

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Discussion Starter #9
killerbee said:
Shim it. EFIlive is the best way to log the pressure reduction if the FPRV is popping, it likely is.
Killer,
In the thread starter I talked about shimming but opted to replace the valve with a new one. I took the old one apart and it looks like shims might work but I couldn't find out how far to shim it. I'm afraid that if it's too tight it might overpressure something. Do you have any info on shimming on a LB7?

Thanks, Steve
 

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Discussion Starter #10
Jared Duramax said:
From the sounds of this i would try checking the mesh screen in the tank on the pick up unit. this maybe dirty causing you issues. if you go this rought i would reccomend installing a billet pick up kit which allows more fuel in to the motor. all the lines after the tank are 1/2 in but the stock pick up is 3/8 in this causes a lot of work that the CP3 dosent need to go through. if you do all of this and it still doesnt work i dont know what to tell you.:shrug:

Jared
Jared,
You brought up an interesting idea too. A little while after Hurricane Katrina I had a problem loosing prime. Found out it was trash in the primer pump that probably came from a transfer tank I was using while supplies were tight. I guess the same stuff could foul the pickup in the tank too. I used an inline filter for a long time but took it off when I started having probs with the fuel pressure thing.

Thanks, Steve
 

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Discussion Starter #11
Just thinking, not something I'm used to and it's giving me a head-ache.

The code I'm getting is p0093, large fuel leak detected (or something to that effect). That makes me think that there must be a big differential in pressures somewhere. I know one pressure input must be at the FPRV. Do y'all know where the other pressure input or inputs are coming from?

Also, doesn't the FPRV open and close all the time in an effort to hold the fuel pressure constant, and not just 'pop' at some inopportune time like when you're racing a powerstroke, or pulling a load up the side of a mountain.

Thanks, Steve
 

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P093 is a low fuel pressure code. You probably have a fuel injector or two with high fuel return rates. This will cause low fuel pressure and will be more noticible when under load. The pcm commanded fuel pressure and actual fuel rail pressure are not close enough so it sets the code. You need to get somebody that has a tech 2 scan tool to check the fuel rail pressure while driving the truck hard to see if the pressure drops. You could also check the vacuum reading on the fuel feed at the test port on the front of the engine to see if you have a restriction causing high vac reading. If you have a restricted fuel filter or restricted sock filter in the tank it will show up on the vacuum test. Your best bet is probably to have the dealer look at it if they have a diesel tech. Too bad that you don't have a Duramax diesel tech next door like my neighbors do. If it is high fuel return from the injectors you might still be under the special policy for injector replacement. Check with your dealer. Good luck.
 

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im not sure what else to tell you im really interested in whats causing this issue but in the mean time if i come up with some thing i will let you know.

Good Luck
Jared
 

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Discussion Starter #14
Jared Duramax said:
im not sure what else to tell you im really interested in whats causing this issue but in the mean time if i come up with some thing i will let you know.

Good Luck
Jared
Update.
Pulled the tank Wednesday night. The fuel pickup was way different than I expected. I couldn't really get to the 'screen' (the pickup, return, sending unit is an assembly) but there was a lot of gunk built up around the pickup itself. I flushed out what I could and put it back together. I couldn't flush the tank because it still had fuel in it and didn't have a way to handle it right then. I'm ordering a billet pickup kit and I'll be ready to flush and clean the tank when I install it. I'll let you know how it goes.

Thanks again,
Steve
 

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sounds good also while you are at it change the fuel filter and check the WIF sensor for cracks. i just saw an LLY that wasnt running right and come to find out the system was loosing pressure through the WIF sensor. but anyways keep us informed with the results.

Jared
 
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