LB7: Fpr ?'s

[ImpalaMax]

Ok 04 Lb7 mods in sig. Few days ago started it up and after about 10 min of idle in started sounding like a powerjoke.
Got P0088-89-90 codes and 1940 rpm limiter.
I always run diesel kleen and fuel filter is 3k miles old.
Well I logged it with Efi.
Desired rail psi is normal but actual is 25-26k no matter what.

I figured a stuck open fpr so I ordered a LBZ fpr to put in it.

My quetion is could driving with high rail pressure take out injectors? I had to drive it home and #4 injector is out of spec but I was just hoping it was due to 26k of rail pessure.
No fuel in oil and no smoke.
Thx guys.

 

[Burn Down]

Maybe... LB7 injectors have high pressure seal problems. Is the rail pressure fixed now and is #4 still out?

 

[ImpalaMax]

No not fixed yet. The lbz fpr should be in on tues Or wed then ill install and ck balance rates again.

 

[bullfrogjohnson]

You are gonna have to change your tune for the lbz fpr fyi. It will run higher pressure than the lb7. I am sure you will be fine with driving it home. I just wouldnt drive it every day till you get it fixed.

 

[ImpalaMax]

Thx for the info Travis. I was reading about re scaling the fpr voltage.

I was more worried about when I drove it home with the bad lb7 fpr @26k actual psi.
It gave me a 1940 rpm limp but still cruised 74 mph on the way home.

 

[bullfrogjohnson]

When I modded my stock regulator mine ran at 24k psi all the time and I had to drive it for about a week until I got the voltage rescaled right. It had no ill effects except a very touchy throttle and embarasment sitting at stop lights.

 

[ImpalaMax]

Good to know. Thank you.

 

[ImpalaMax]

What actually goes bad in them? Just gunk build up? I was wondering because if I can mod this one ill use it in the Impala LB7.

 

[rcr1978]

Maybe... LB7 injectors have high pressure seal problems. Is the rail pressure fixed now and is #4 still out?

I know they where not designed for a 180mpa but I run 170-175Mpa on mine with no problems yet, 170Mpa on my tow tune and I'm hitting it 175Mpa on my bigger tune but usualy only hits around 173-174mpa under load.

When you say seal problems are you talking about guys with dual Cp3's, no releif valve, and probably pegging over 200Mpa on a let off? I don't think a stock sensor will read over 183.4 since this is the max I've seen in all my logs and it's on a let off (rail spike). I'm still on a stock Cp3 and injectors, if I had duals and bigger injectors I wouldn't be testing these waters

 

[Burn Down]

I know they where not designed for a 180mpa but I run 170-175Mpa on mine with no problems yet, 170Mpa on my tow tune and I'm hitting it 175Mpa on my bigger tune but usualy only hits around 173-174mpa under load.

When you say seal problems are you talking about guys with dual Cp3's, no releif valve, and probably pegging over 200Mpa on a let off? I don't think a stock sensor will read over 183.4 since this is the max I've seen in all my logs and it's on a let off (rail spike). I'm still on a stock Cp3 and injectors, if I had duals and bigger injectors I wouldn't be testing these waters

When I say high pressure seal problems, It's from discussing rail issues with Greg @ Exergy Engineering. Greg and others have told me a very common problem they see in the LB7 injector is High Pressure Seal failure.

The OP asked if running the truck with the rail maxed out coulkd have hurt number 4, I simply said maybe...

 

[rcr1978]

When I say high pressure seal problems, It's from discussing rail issues with Greg @ Exergy Engineering. Greg and others have told me a very common problem they see in the LB7 injector is High Pressure Seal failure.

The OP asked if running the truck with the rail maxed out coulkd have hurt number 4, I simply said maybe...

I wasn't trying to put you down or say you didn't know what your talking about, I was wanting to find out what the seal failure was and where? I also stated what I've been doing for the last 5+ years on my truck with no issues yet. I know it's a little bit of a thread derail.

 

[Burn Down]

I wasn't trying to put you down or say you didn't know what your talking about, I was wanting to find out what the seal failure was and where? I also stated what I've been doing for the last 5+ years on my truck with no issues yet. I know it's a little bit of a thread derail.

No ones bent on my end. Just answered your question. The seals are internal in the injector. The newer LB7 injectors (the ones that GM put in for warranty & the reman ones that are available now) have better seals but it still is a issue compared to the later series injectors.

 

[bullfrogjohnson]

I had to drive mine with high rp because I didnt have another choice. I still had to get to work and when I modded mine it was back in 06 when it first came around and re scaling the voltage was a shot in the dark. I would not recommend anyone to do what I did. I got lucky but you could very easily blow the seals out in the injector or torch a piston.