Help: Need Help , ASAP, Rail pressure problem

[TrentNell]

I finally was able to stay in it long enough to run through all the gears yesterday ,I am having a problem with rail pressure , its doing the same thing it did my last run @ RMR .I figured it was the FPRV valve at the time , now it is welded shut and there isnt one in the picture . It seemed to be working fine the firsat night i drove it , but wasnt logging and was only in it a few secound each time i went WOT

Things i have checked so far ...................

unplugged both regs 1 at a time and both will max out rail pressure when unplugged .

using EFI I manually commanded 160 mpa and it holds it perfectly at idle but still wont hold it during a WOT run , ( see attached log )

un-hooked my feed line and routed it to a pan and turned on lift pumps , it pumped fuel out faster than then funnel could drain it ,about 1 gallon in 10-15 seconds so it doesnt seem to be a supply problem .

have spent alot of time looking for leaks and cant seem to find any that are visual any way .

still need to do a bottle test

haven't seen it making any oil but don't know if i have driven it enough to see it on the dip stick , i will be changing the oil soon so i will visually inspect it when i do .

Any idea's I am missing ?

 

[LBZ]

Sure wish I could see the log. Stupid work computer....

I would guess if a bottle test comes back good then it must be something in your tune because it sounds like you definetly have the fuel. The fuel system is all new plumbing so restrictions from bad hoses aren't likely an issue unless it is right at the FPR's themselves or the inlet fittings.

I know Simon had a few things that had to be worked out with tuning after it all got put back together. Hopefully he logs in and can help you out today!
How big of a PW did you go?

 

[TrentNell]

Sure wish I could see the log. Stupid work computer....

I would guess if a bottle test comes back good then it must be something in your tune because it sounds like you definetly have the fuel. The fuel system is all new plumbing so restrictions from bad hoses aren't likely an issue unless it is right at the FPR's themselves or the inlet fittings.

I know Simon had a few things that had to be worked out with tuning after it all got put back together. Hopefully he logs in and can help you out today!
How big of a PW did you go?

Commanded rail stays steady , or where it is supposed to be anyway .in thelog the commanded is from 25k-27k depending on rpm , it starts out holding 23-24k at 2600 ms then drops down to 19k in turn dropping pulse down to 1600 ms from 2600 ms ( keep in mind pulse width drops with pressure because its tuned to be that way ) and it still stays low untill after a bit the pressure goes back up for a bit ,pulse width rises with it holds for a sec then drops again , even after i let off something is screwy because desired is 8k and it drops to 10k then goes up to 16k for a bit and the TPS stays at 0 and commanded doesnt change from 8k I have a spare CP3 i can swap in the see if that helps but ??

 

[ripmf666]

Were is the fuel pressure sensor at stock area or move now. If you have one of the I would swap that out.

 

[LBZ]

Commanded might stay smooth, what does rail current do?

 

[sweetdiesel]

Ok so no leaks on the outside means injectors. If you hVe excesive fuel return it still means injectors right? A balance rate would tell us so
something isn't right
bad cp3 would have to be 2 bad cp3 and if they maintain at idle then that dosnt sound like a cp3 to. Me?
Does it start ok

perhaps bad fuel supply but if you had the issue before then?

Just call me when you get a second Trent ad I'm sure your busy now

 

[sweetdiesel]

Were is the fuel pressure sensor at stock area or move now. If you have one of the I would swap that out.

Henry good point I believe Trent still has the stocker in the original location that would be easy to check though

 

[LBZ]

With that much fuel flowing Simon, I doubt you would see a bad CP3 at idle either way with the PW commanded at idle no? I would think even one CP3 with a bad plunger could maintain rail at idle.

High flow return rates would tell you if you have a bad injector on top of balance checking.

 

[TrentNell]

Balance rates are good , Fuel pressure sensor is still in stock location , I have another one i can swap it with . I just tried to call you call Simon . I need to do a bottle test that will tell me alot , just didnt have time last night . Any other idea's ?

Edit:Like i said before , at idle pulse width if i command 160 mpa , it holds 160 mpa just canbt keep up with the bigger pulse , I dont think its the Cp3's as of right now , I am thinking the pressure is bleeding into the return side ,just have to find out for sure if it is , and then figure out where .

 

[MMLMM]

Bottle test for sure...what do you mean you welded the frpv shut? Did you just weld the rail up or weld in a fitting?

 

[TrentNell]

Bottle test for sure...what do you mean you welded the frpv shut? Did you just weld the rail up or weld in a fitting?

The FPRV itself is welded shut , the end of it that the bango bolt screw into, that normally hooks to the return line , I put a plug in it and welded it shut , I have verified that it is not leaking , in fact i have yet to verify any external leak ,IMOP it is either leaking into the block and it just hasn't made enough oil yet or i havent drove it enough to be visible on the dip stick , or it is going out the return side from a bad injector ?

 

[ripmf666]

Bottle test for sure...what do you mean you welded the frpv shut? Did you just weld the rail up or weld in a fitting?

It's not in the rail like are trucks Mike it's in a spliter block behind the cp3 in the valey

 

[JoshH]

How do you do a bottle test on an LB7?

That log looks strange. It actually holds better rail pressure with lower pulse width. Maybe rig up a switch to cut connection to the CP3 regulator. See what rail pressure does when they are disconnected.

 

[TrentNell]

How do you do a bottle test on an LB7?

That log looks strange. It actually holds better rail pressure with lower pulse width. Maybe rig up a switch to cut connection to the CP3 regulator. See what rail pressure does when they are disconnected.

I was just going to seperate the return lines for each head from my splitter block and run them into a bottle/container , max out rail and watch to see how much comes out the return line , if there is a difference from 1 side to another then it should tell me something , unless both sides were faulty ? Good idea on the switch , it would rule out the cp3 controller anyway .

 

[TrentNell]

Also , for a basis of comparison , here is the log from my 11.0 pass , same cp3's and injectors . And one from the very next pass when this problem first popped up last year , the truck hasn't really even ran from then till now and the injectors and cp3's are unchanged . these 2 runs were 2 hours apart and nothing changed between runs .

 

[x MadMAX DIESEL]

Maybe your cp3 belt is slipping?

 

[TrentNell]

Maybe your cp3 belt is slipping?

Maybe , could explain why i didnt feel it the first night , but was there the secound ? I did loose a bunch of trans fluid from the line blowing off behind the grill , It might be worth looking into ,hoping I can get out there tonight to work on it for a bit , but will have to see . Only problem with that theroy is the factory cp3 alone should put out more fuel/holdrail better then what i am seeing right now ,the belt would only affect the second CP3 I woud thinkit would be making some racket also if it was slipping .

 

[paint94979]

Maybe , could explain why i didnt feel it the first night , but was there the secound ? I did loose a bunch of trans fluid from the line blowing off behind the grill , It might be worth looking into ,hoping I can get out there tonight to work on it for a bit , but will have to see . Only problem with that theroy is the factory cp3 alone should put out more fuel/holdrail better then what i am seeing right now ,the belt would only affect the second CP3 I woud thinkit would be making some racket also if it was slipping .

obviously something changed mechanically between your 11.0 to the ALLOUT(titled) pass have you disabled the 2nd CP3 entirely and done a WOT run? That would isolate the belt slipping or a problem with the CP3 itself

 

[TrentNell]

obviously something changed mechanically between your 11.0 to the ALLOUT(titled) pass have you disabled the 2nd CP3 entirely and done a WOT run? That would isolate the belt slipping or a problem with the CP3 itself

I haven't yet , but it is the list of things to try , going to start with checking the return rate for both the injectors and CP3's , then try Joshes Idea of the "switch" , and if i havent found it by then , I with pull the belt and dual cp3 wiring and test the pump in the valley . If i wasnt so short on time wouldnt be too worried about getting it figured out , but i need this sorted out by next weekend or else it is pointless going to the race in AZ with it the way it is , I think i will get it figured out in time though .

 

[jneal]

Maybe , could explain why i didnt feel it the first night , but was there the secound ? I did loose a bunch of trans fluid from the line blowing off behind the grill , It might be worth looking into ,hoping I can get out there tonight to work on it for a bit , but will have to see . Only problem with that theroy is the factory cp3 alone should put out more fuel/holdrail better then what i am seeing right now ,the belt would only affect the second CP3 I woud thinkit would be making some racket also if it was slipping .

IMO Trent the belt slipping sounds like a very good possibilty. If the 2nd CP3 belt is slipping the factory location CP3 might not be able to keep up due to the duty cycle to the FPR is being split between the 2 CP3's by the CP3x2 controller.