Low Rail Pressure

[JD Dave]

Having trouble holding railing pressure. My lift pumps pressure seems to be good but I have trouble keeping over 20k on my big tune. Rob says it should hold it fine. I've bottle tested it and checked for leaks and everything is fine. I have no factory filter. Just not sure where to go from here. Its not setting any codes either. I'm having trouble getting over 50 psi of boost and I think this is my problem. I have 120 over Socal injectors, dual stock pumps and the balance rates are good, should I do a return rate test. Any suggestions? I have a fass 95/150 feeding each cp3 and I'm using the stock return line. I was wondering if there's any chance of my return line being to small. Can't see how that would effect rail though.

 

[JD Dave]

To find your pulse width your running is that on the bottom right of Main Injection Pulse chart?

 

[paint94979]

Having trouble holding railing pressure. My lift pumps pressure seems to be good but I have trouble keeping over 20k on my big tune. Rob says it should hold it fine. I've bottle tested it and checked for leaks and everything is fine. I have no factory filter. Just not sure where to go from here. Its not setting any codes either. I'm having trouble getting over 50 psi of boost and I think this is my problem. I have 120 over Socal injectors, dual stock pumps and the balance rates are good, should I do a return rate test. Any suggestions? I have a fass 95/150 feeding each cp3 and I'm using the stock return line. I was wondering if there's any chance of my return line being to small. Can't see how that would effect rail though.

I'd do a return rate test and see what it shows... what is the history of the injectors?

 

[JD Dave]

I'd do a return rate test and see what it shows... what is the history of the injectors?

They have 500 miles on them and 20 pulls. I got them from Guy last spring and the cores has 12k on them from my stock motor.

 

[sweetdiesel]

I was wondering if there's any chance of my return line being to small. Can't see how that would effect rail though.

highly doubt it

To find your pulse width your running is that on the bottom right of Main Injection Pulse chart?

yes

 

[TDFDiesel]

I'm assuming you have dual cp3s from your post?

 

[JD Dave]

highly doubt it



yes

Thanks So my pulse width on my big tune is 2860.

I'm assuming you have dual cp3s from your post?

Yes with stock pumps.


Im going to try and get what I need to do a return rate test now. Is there a fuse \i can pull instead of the bale connectors?

 

[sweetdiesel]

Thanks So my pulse width on my big tune is 2860.


Yes with stock pumps.


Im going to try and get what I need to do a return rate test now. Is there a fuse \i can pull instead of the bale connectors?

my rail starts to drop with that much fuel too, Depends a lot on the tune also.

not sure what the fuse is on a LMM but look for" inj "fuse that might work if you just dont want it to start Dave

 

[paint94979]

Thanks So my pulse width on my big tune is 2860.

Jesus Dave that is a lot of fuel with 120% over injectors

 

[JD Dave]

Jesus Dave that is a lot of fuel with 120% over injectors

That's what I'm thinking but I don't know much. I wonder if it's just not possible to hold it with stock pumps. I've pulled so many fuses and it either starts or won't turn over. I love working on my truck I love working on my I love working on my truck. LOL

 

[paint94979]

That's what I'm thinking but I don't know much. I wonder if it's just not possible to hold it with stock pumps. I've pulled so many fuses and it either starts or won't turn over. I love working on my truck I love working on my I love working on my truck. LOL

LOL Kelly had a similar issue running huge pulse width on 100 overs dropped pulse width and gained ET

 

[x MadMAX DIESEL]

That is soo much fuel. Back down the pulse and you will get more rail pressure and more power, won't hurt to try.

 

[Dallas S]

similar subject. Im having issues keeping rail pressure. 60%, twin stock CP3's, 2200pw, 190mpa, fass 150 no filter, stock filter head and filter. and stock pickup... WOT by the time the 3-4 shift happens it just runs outa steam. im assuming/hoping all the problems are from the stock pickup. sound resonable?

sorry for hijacking..

 

[sweetdiesel]

That is soo much fuel. Back down the pulse and you will get more rail pressure and more power, won't hurt to try.

Better yet get a bigger pump and bump up the PW:hello:

 

[sweetdiesel]

That is soo much fuel. Back down the pulse and you will get more rail pressure and more power, won't hurt to try.

Better yet get a bigger pump and bump up the PW:hello:

 

[JD Dave]

Better yet get a bigger pump and bump up the PW:hello:

So good you said it twice. That will be the plan just want to try and get it running the way it is for now. It seems to hold 2000 PW but over that I loose rail. Tony B told me to put a switch in the cab from my duel fueler and when I'm under wot make the duals go to full pressure and that will tell me if it's a tuning issue for sure. I want to try that but just want to make sure I have it setup right as not to screw something. Do I have to put the switch from the power on the dual fueler or from the plug on the regulator. I guess I want both pump to go to max pressure.

 

[xcablb7]

That's a ton of fuel !!!! Holy sh!t, I made 830 and went 126 mph with 80%s and 2590 pw

 

[sweetdiesel]

I made 830 and went 126 mph

thats so yesterday though....if ya aint making 1200 your just not dumping enough fuel now


are the lmm tips not smaller than LB7?


Dave can you run a tune with like 2700pw and see wwhat your rail is like?

 

[xcablb7]

lol youre right simon im gonna go put a 3600 pw in it now:spit:
and i forgot the lmm tips were smaller have to see if i can find the lpm of each

 

[McRat]

Check the plumbing on your CP3's and make sure you're not feeding one with the return of the other. It's an easy mistake to make. Both CP3's should feed from their metal .218" ID nipples (passenger side nipple), to a T, then to the fuel filter.