Low rail pressure on race tune?

[dmaxbowtie]

i am having similar issues, xcablb7 logged my last 1/4 mile pass and my rail pressure drops lower, i am going to change my airdog filter and stock filter again and add a billet fuel pickup which i think the billet pickup is what is needed in my case and possibly yours, i feel the volume of fuel at wot cant keep up with the stock fuel pickup assembly. do you have a billet pickup? does anyone know how much the stock sending unit can handle hp wise or rail pressure wise?

 

[Devon]

maybe a billet pickup is required in our situation,but there are also plenty of people that don't run a aftermarket pickup.the most I am seeing on my race tune for rail pressure WOT is 20,000 or so..would it be any bit beneficial to go into efilive and disable the check engine light to come on preventing fuel limp,so I can drag it tonight and not lose alot of power at the end of the track due to the fuel limp?

 

[Trotorx2]

Devon

I'm having the P0087 code also with the Acid Tune. I'm waiting on Dustin to get some AutoCals so I can log my truck.

I'll keep watching this thread for updates.

 

[Devon]

Im going to the track tonight and definatly logging all of my runs so I will let you guys know what's going on.. Hoping for atleast a 12.99 lol


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[x MadMAX DIESEL]

I got one 12.85 with low rail pressure. And you can't block that code from limping the truck

 

[1lowdiesel]

All this talk about clogged filters and whatnot, Do you know what kind of fuel pressure you have going to the CP3 at idle and under a load?

If you set the reg at 12 psi you shouldn't drop more than 2-3 psi under heavy load.

A new spring will do nothing. The chance of the spring getting weak in that short amount of time is not possible.

Put a gauge on it and see what you've got, then go from there. W/o knowing what kind of pressure you actually have, all you're doing is guessing at potential issues.

 

[Devon]

I know at idle I see 11psi on my fuel pressure gauge.but that gauge is also mechanical and under my hood.so I can't see when I'm WOT. Also i don't think you can get rid of the limp, I turned both p0087 dtc codes to non emission MIL off and still limps, just doesn't show the check engine light.


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[x MadMAX DIESEL]

I wish there was a table where you could change the min-max difference between actual and desired rail pressure before throwing it into fuel limp. Because I'm in the same boat as you, low but not wayyy low but still limps around 80

 

[1lowdiesel]

You should get some more hose then and run it up into the cab so you can actually see if it is dropping under load. Just some 1/8" line and a compression union and you're good.

 

[x MadMAX DIESEL]

Yeah I did that when I only had an gauge in the doghouse. Just duck taped the gauge to the windsheild and went for a spin. Just remember to don't hit the wipers

 

[Trotorx2]

So where and how would I hook up a gauge to read the fuel pressure? I'm having the same codes throw on the Acid tune.

My truck throws the code even when I'm not at WOT.

 

[1lowdiesel]

On the top of the pump, directly above the fuel filter there is an 1/8" pressure port(It's got a plug in it right now). Use a mechanical liquid filled gauge if possible.

 

[Trotorx2]

On the top of the pump, directly above the fuel filter there is an 1/8" pressure port(It's got a plug in it right now). Use a mechanical liquid filled gauge if possible.

Thanks for the info! :thumb: I'll go look. I have access to liquid filled gauges just not as high as I'm figuring I'll need.

 

[Devon]

You will only need a 15psi gauge.


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[x MadMAX DIESEL]

I have the acid tune also

 

[Devon]

I'm not doubting dustins tuning one bit as it's phenomenal, but could this p0087 be caused by something in the tuning itself? Seeing 3 of us have his tunes and are throwing that code on the race tune


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[x MadMAX DIESEL]

Yeah I wish I could figure it out.

 

[Trotorx2]

I've talked to Dustin several times about this it seems to be with just a few trucks. I didn't buy an EFILive box from him as I didn't want to be able to change settings...I'll leave the tuning to him...I'm waiting on him to ship me an Autocal box so I can log the truck and then sent the file to him. I hope he gets it to me soon as I'm wanting to go the track soon.

 

[ripmf666]

Does not take long to get a autocal shipped out.

 

[Trotorx2]

I know