Where is your fuel pressure tap thats reading the psi from the air dog. do you still have the fuel to the cp3 running through the oem filter? you can shim the air dog, but the problem could be as simple as leak in the system.

Shimming the fprv is one thing you really cant not do if your going to be adding power, especially on a lly.

you can try unpluging the fca first and see what heppened to the RP at idle it shoul jump up to about 26kpsi

 

Still running throught the OEM filter. Trying to keep the fuel in the system as clean as possible. The more filters, the less likely something is to get through. I do not have a pressure gauge on the air dog. If I turn the air dog on, there are no leaks that show up. I did have a leak in the fuel cooler(Cracked the inlet fitting). I have it bypassed for now, looking for a replacement (found one for $200). I am looking at gauges now. Thinking about PLX, AeroforceTech, or ISSPRO. I like the PLX setup.

 

sometimes the fittings arent tight and the fuel pump can suck in air though the fittings, but having a FP gauge will help with diagnosing that.

The air dog runs about 10-12psi in the system all the way up to ur oem filter.

if you were to place ur fp tap on the other side of the filter on the line that goes to the cp3 you would see around 8-10 psi and it would slowly get lower over time due to the filter getting dirtier. but posotive pressure is still good. the cp3 can run on a -5 psi vacume iirc before the filter needs to be changed.

You should look into shiming the fprv before doing anything major the kit only costs about 12 dollars. i got one laying around if you want it lemme know

 

I don't think that there are any fittings leaking, I have no spilled fuel when running. Also to fill the air dog filters, I pulled a slight vacuum on the to engine line, and ended up with a puddle of fuel where I was working. Another quick test (IMO) is when the air dog is running, I cannot hear air bubbles in the tank. I know that it is possible to hear the air bubbles when the air dog is running as i could hear them when I first started the system after the install. This was due to the return lines being full of air.

I do not have a fuel pressure gauge yet, still trying to figure out which ones to put in. Looking toward the PLX.

I only have 110k miles on the truck. Yes I bought it new, it's only been to the dealer once for engine related issues (98k had 2 bad injector plugs). It only started this stumbling thing less than 5k ago.

I tried the transmission fluid in a tank of diesel. No luck. Added a can of SEA FOAM. No luch. Used a fuel additive for 5 tanks. No luck. Now I am thinking that the FPRV may have trash in it. Like I said before, the air dog is capable of pushing fuel through the system back to the tank. Found that out when the fuel cooler started leaking. (100% my fault.) I have that bypassed for now, found one at a dealer for $200.

 

atf and sea foam r u crazy?

how does the truck sound at idle, is there a loud tackin noise goin on, have you ever thrown any codes like a p0087?

 

You can pull the return line off air dog, there is a spring
in there that controls pressure. Stretch spring and that
will give you more pressure.

 

Trans fluid an sea foam at different times. No ticking noise. I get low fuel rail pressure (don't remember the number) occasionally, not every time. I have changed the fuel filter after this code. Also added air dog (less than 3 tanks of fuel on new filter) only tripped the low rail pressure one time.

I was wondering if the FCA valve can be stopped up, or if the FPRV could be getting "weak" and not holding pressure when it should.

---AutoMerged DoublePost---

[QUOTE=2500HeavyDuty;268249]atf and sea foam r u crazy?


Not crazy but been accused of being insane by more than one person.

 

you can also add 5/16 washers in there and shim it for more pressure instead of stretching the spring.

Before u go spend a few hundred dollars or maybe a few hours of ur time, one thing that helps out with the low fuel pressure code u occasionally get is shimming the FPRV, the kit only costs about 12 bucks and it really helps out with keeping rail pressure on the lly's

 

Looked at the PPE shim kit. It looks simple to do. I think I can take the FPRV to the hardware store and get the stuff to shim it. It looks like the kit is just a combination of 3 washers and a nut to pull the end of the FPRV off. I have seen them for about $20 including shipping. My guess is that there is about $3 worth of stuff from the local hardware store.

Will probably tackle it next weekend when I get over the bronchitis that started last week. Been cooped up in the house all weekend.

 

im out in katy, i have a shim kit if you want to pick it up