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03’Duramax LB7 limp mode

3K views 18 replies 4 participants last post by  BillB3857 
#1 ·
New injectors last year. It’s been running great.
Then limp mode. Check engine light, loss of fuel gauge. P2146 p0201 p0203 p0206 p0207 codes.
Checked every wire and harness under the hood. Checked grounds. Pulled valve covers and rechecked injectors and wiring. Couldn’t find anything.
FICM failure because of new injectors?
ECM?
PCM?
I’d hate to spend $1200 on a FICM and that not be the issue.
 
#2 ·
Welcome to DieselPlace
Any mods done on your LB7?
 
#6 ·
It shouldn't cause that issue..

Did you inspect the pins of the FICM connector? They can work loose/push back, etc.
 
#8 ·
What are the actual vs desired fuel pressures?
 
#17 ·
Yes, there is a test to check if the FPRV is bleeding off rail pressure-- "Bottle Test"

Remove the "U" hose from the back of the fuel rail- plug the hose. Attach a piece of hose to the fuel rail nipple and insert the hose in a bottle, now drive the truck hard with a few full throttle runs- if the FPRV bleeds off fuel into the bottle, the valve is bleeding off pressure. That can affect performance.
 
#19 ·
The last limp mode I had was due to a bad NBSU switch. How are your shift indicator reading?
 
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