LB7: Rail Pressure Issues
- Thread starter durallymax
- Start date
You can't do it that way on an LB7. They're completely different.
I would be very hesitant to try that. If your valve was leaking, you would built 20k+ PSI behind the banjo bolt. I'm not sure it could hold up to that much pressure.
There are several pulling trucks out there that have plugged the junction block where the relief valve goes. The plug on the end of a fuel rail screws right into it.
I pulled the banjo bolt and plugged just the end of it because we thought my pump was returning to much it didnt make a difference but i guess i did eliminate 1 thing.
Oh yeah i have the same problem as you just not as bad we comand 22,000 and it delivers 17 or 18 mine will gradulay get up to where comanded and supplied are the same but out of the whole or even geting on it lightly its way off but i dont set any codes for low rail yet.I have a brand new lbz pump im going to put in the valley as mine is somewhere around 160,000 and is probably getting tired after that its new injector time.I was wanting 60 overs anyways
This truck is perfect. Its smooth and dead nuts all the way to 18,000 then nothing.
I dont think it is an engine limp. Correct me if I am wrong, but without looking doesn't engine limp limit you to 2,000RPM usually. This truck runs fine the full RPM range as long as it never commands over 18,000psi. I know there are several stages of engine protection, does this sound like it could be any of them? I could look through the stock tuning on the truck to see if any parameters match.
Im going to start by logging everything again just to double check if there is anything noticeable there as well as see if I can get any codes to surface. Also going to compare the stock tune to another stock tune to make sure the truck is set to stock.
I think then i will follow the return rate procedure outlined in the GM books.
If nothing shows up there, Ill start swapping parts until I find something.
Thx Pat ive done a couple and when it comes apart im going to take my time.im getting larger fittings,im going to run 1/2 line up into the motor compartment to a 3 way y where im going to take off with 2 3/8ths lines1 will run straight to the ficm and then to the pump in the valley i think i will eliminate the stock filter im going to do burn downs filter and water sep the second line will be for the dual fueler pump the 3rd hole will have a plug for bleeding air after filter changes and im going to drill and tap a 1/8th inch hole in the top of the fuel y for a gauge to screw rite in so i can tell the presure from the pump.Bought the 12 mm to 6an larger fittings from ATS that screw rite into the cp3 and bought all blue (an) fittings for a nice looking job.
Are you making all Braided AN hoses for it as well? Went through all of that on our pulling tractor, takes awhile but looks nice, holds up well, and is very serviceable down the road.
Nice sounds like your on top of it! Make sure you do a write up after. I'm interested in the hose setup.
I'm sure that works perfectly as those fittings are designed for the pressure. The way I'm reading the other post, he blocks the end of the banjo bolt uses the banjo bolt as a plug to keep the relief valve from leaking to the return. If the valve is leaking, I'm not sure the banjo bolt would be able to hold up when the pressure really starts to build up behind it.There are several pulling trucks out there that have plugged the junction block where the relief valve goes. The plug on the end of a fuel rail screws right into it.
If the valve itself is leaking, it should be easily determined in the return test right? Seems as if it would be just from reading through the book on it. Because there would be a high return rate of fuel through the valve. Although i wonder if you would notice it because they want you to do the test without actually running the truck and all of their numbers are based off of that, so I suppose you might not build enough pressure for the valve to leak and were back to square one of just swapping it to see if it is the culprit after the return test.
Answering my own questions again. useless post by me, going up anyways.
Answering my own questions again. useless post by me, going up anyways.
Not going with the braided the stainless just seams like it cuts thru anything it touches thought about doing the nylon braided but i just went with the black fuel line for now my chnge it it later i think with the braided lines if you dont do them all it doesnt look that nice.
Pat ill do a video on it.
Josh here is the write up from diesel bombers http://www.dieselbombers.com/chevrolet-diesel-tech-articles/21777-plugging-lb7-fprv.html?ref=esp-img
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checked returns. Only got 10-12ml of fuel returning out of system minus pump. GM book says replace pump?
What did you get figured out? I have an Issue on my LLY. My top tune from rob is close to 500rwhp and it will go full power, then I let off and floor it again and it feels slower than stock annoying, It has a brand new LBZ fpr and FASS 150gph. I have the PPE shim kit, would it be worth it to put it in with this issue?
annoying, It has a brand new LBZ fpr and FASS 150gph. I have the PPE shim kit, would it be worth it to put it in with this issue?What did you get figured out? I have an Issue on my LLY. My top tune from rob is close to 500rwhp and it will go full power, then I let off and floor it again and it feels slower than stock
Yes, it sounds like the shim kit will fix your issue.
Yes it would be worth it.
I ended up replacing the cp3. The stock one apparently was weak. New pump and everything was cherry again except now I have an extra fpr. O well I'm sure ill use it.
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I ended up replacing the cp3. The stock one apparently was weak. New pump and everything was cherry again except now I have an extra fpr. O well I'm sure ill use it.
Sent from my Motorola Electrify using Tapatalk