Since iv had my lb7, it has had low rail pressure. I had an injector returning too much when I bought it causing hard start issues. Replaced that injector and all has been good. running tonys tuning. I sent him some logs and with a 3100 pulse width, it was dropping pressure pretty hard. Around the 17,000-18,000psi range. I bought a brand new lbz pump and installed it with some 45% nozzles at the same time. now with the tuning adjusted, I am still dropping pressure down into the same range. I have good balance rates and command rates. Truck has 260k miles on it. No fuel leaks. Anyone think the relief valve could be bad? I mean realistically is there any other pieces of the puzzle that can cause low rail? Iv read that lb7s have horrible relief valves and that if they pop once, they are pretty much done. I was thinking about putting the race plug in or welding it shut. Any ideas on this?
relief valve bad?
- Thread starter onebaddmaxxx
- Start date
I could be wrong but i thought the lb7 relief valves were very stout? If it's not the relief valve being bad then it's your injectors. That's basing the theory your new lbz pump is not returning to much fuel.
yea you would think. I read on here earlier that they sucked. And likely after they pop the first time they are hurt and get weaker and weaker
No In original post you can see it said tuning adjusted after I put 45s in. Now it's around 2500 I believe.
most weld them shut, you can shim it with a couple of washers incase you still want the valve functioning.
Link on shimming it
http://www.dieselbombers.com/01-04-duramax-lb7-tech-articles/34726-lb7-fprv-shim-mod.html
Link on shimming it
http://www.dieselbombers.com/01-04-duramax-lb7-tech-articles/34726-lb7-fprv-shim-mod.html
Making "Tuning Adjustments" could mean anything.
I'd plug the relief right off and see what happens.