Alright so i just installed my airdog 2 df-165 last week and a few things are strange.

The first thing is that my fuel pressure gauge is jumping like 3-5 psi at idle. I dont know if the pump has some type of bypass valve to where it will build pressure and relieve it and thats why it keeps jumping around? I dont know.

Second thing is holding pressure. When I installed the pump on saturday it was preset to 50 psi. On sunday I bumped it up to 60 psi. Well on wednesday I noticed it dropped down to 50 psi. So I adjusted the regulator up to 80 psi. And what do you know thursday it went down to 65-70 psi. And now today its back down to 50 psi. And I kept making sure the packing nut where the regulator is was tight.

Any help I would appreciate it.

 

Don't forget the regulator in the filter housing on the engine.
If it is setup for a lower pressure that is the pressure
that the system will try to maintain.

Sean

 

In addition to the factory regulator "blowing off" (have you done the blue spring upgrade?) there is an o-ring on the end of the pressure regulator piston in the in the airdog that will break and allow your pressure to fluctuate wildly. They send an extra o-ring with the pump just for that reason. To access it you have to unscrew the regulator screw and extract ALL the parts of it. I used a very large q-tip to pull the small piston out. If that's not the culprit then it's the factory regulator.

 

I did do the upgraded blue spring over the summer. But how can i check and adjust the factory regulator?

Thanks for the replys guys

 

You can't adjust the factory regulator (under the hood) that's what the blue spring does. It raises the fuel pressure because it's longer/stiffer and takes more pressure to open the relief. I suspect you have a bad o-ring on the ADII pressure regulator. I've experienced it before but I don't think it's very common. It only takes about 5 minutes to change. One other thing does come to mind. The larger fuel volume of the AD2 could be causing the factory regulator to open and not allowing it to close back consistently. You might actually try lowering the pump pressure to see if you get a more consistent fuel supply. Higher pressure doesn't necessarily mean higher volume. I keep my AD2 set between 55 and 58 and never see it fluctuate.

 

I have been reading and askong around and the problem seems to be at the FPR. Since the AD2 have a built in regulator wouldnt it make sense if the internals of the FPR were removed and the airdog control it?

 

That won't work. What you'll have to do is make the FPR spring stiffer so it won't pop off as easily or go with a regulated return system. It's a balancing act to get the fuel pressure right so that the AD2 functions properly and you still get the proper amount of fuel at the injectors. Let me say again: Higher fuel pressure does not necessarily equate to more fuel at the injectors. It can actually mean less. A pump that can pump 100 gph of fuel at 50 psi may only be able to pump 20 gph at 60 psi. I know this is an extreme example, but it's for illustrative purposes and I don't know exactly what the AD2 is rated at.

 

You need to eliminate the OEM FPR. The FPR has now moved from the engine back to the AD2. I plugged the OEM FPR return line fitting. Now I have one fuel line going to the OEM fuel filter. I also eliminated the fuel filter and filter mounting stem in the in the engine fuel filter. My fuel pressure at start is normally around 50 psi due to GP operation. After start is around 70 psi at idle once GP cycle completes and around 60 to 65 psi running 60 to 70 MPH.

DSMMH

 

Hey DSMMH. Do you have a write up and or pictures. Because I'm pretty sure that's where my problem lies. Thanks