Fuel system issues

6.0 Tech · Aug 26, 2016

I have an air dog 2 which is dropping pressur now. I realize i need a better pump, but funds are limited at this point, so a fuel lab is out of the question. It started about a month ago, so i changed the fuel filters, a i realized i had forgotten when i changed them, and it turned out it had been about 20k. I run a 2 micron and 10 micron napa filters. Pressure drop is still there. Noticed getting on the highway today, up to about 80-100mph its down at 40 psi. Pressure is set at 62-65 at idle, and hadnt dropped of that until a month ago. I have the pressure regulator screwed all the way in, and am using my driven regulator for pressure regulation.

Pump is wired into factory pump wiring, i have an xdp sump, and the driven regulated return. It also seems that since the sump install, the pump will somewhat lose prime if parked nose up on a decent hill.

Any ideas? How would igo about testing the regulator, as that shouldnt keep the truck down as long as not having a pump.

Thanks

Merc82 · Aug 27, 2016

How did you route the hose from the sump? I'm thinking a supply/restriction issue.

6.0 Tech · Aug 27, 2016

From the sump it goes pretty straight to the pump. I cut a hole and added about an ich on my skid plate to clear the.sump and.hose, hose sits on top of skidplate, and runs up to the frame, its zip tied to the front fueltank strap and runs straight to the pump.

FaSSt9602 · Aug 31, 2016

I would agree to check the routing of the suction line...If it is losing prime, something could be a miss.

Also AD has a newer improved motor that is supposed to completely eliminate the shortcomings of the earlier generations. They will warranty yours out for the new style.

Airdog 4G

Strictly Diesel · Aug 31, 2016

Pull the regulator assembly out and see if the internal o-rings need to be replaced. This is a fairly common problem with those, and replacing the o-rings may very well restore your lost pressure.

Strictly Diesel · Aug 31, 2016

BTW, I mean the regulator in the AirDog, not our regulator.

6.0 Tech · Sep 1, 2016

Ok, thanks Dennis. Suction line is routed as a straight shot, dont think thats the issue. I will pull out the ad regulator and check the o rings. Noticed today it is dropping to 55ish at idle when warm. Concern is more prevalent when warm, holds pretty steady when cold.

Strictly Diesel · Sep 1, 2016

If the pump motor sounds ok, the harness isn't getting hot, it isn't blowing or melting fuses...problem may not be in the motor (which was the most common issue with those). Next in line is a leaking regulator. Because of the STUPID design that recirculates fuel in circles inside the pump, if the o-rings take a crap, you get fuel pressure drop with no other symptoms (no leaks, no noise...just less pressure). If they would just get rid of that POS regulator, we would consider selling them again. I think they took care of the motor issues with the 4G model, but that regulator design just plain sucks!

6.0 Tech · Sep 1, 2016

I appreciate the info. I wasn't fully aware of the issues of the air dog and fass systems when I bought the pump, but now wish I had gone with a fuel lab. I will be pulling the regulator out after work, and will be replacing the o rings. If that doesn't fix it I will be calling them to see about warranting it. I agree in that the issue probably isn't with your regulator, was just wondering if there was an easy way to test it prior to calling in on the pump, as I knew that was going to be a uestion that was asked as far as other things it could be. I was not aware of the regulator o rings in the air dog itself. And I apologize if it seemed I was condemning your stuff, I was not trying to come off that way. I am very happy with the way the whole setup is. :thumbsup:

6.0 Tech · Sep 1, 2016

Ok, changed all 3 o rings on the regulator, and no change. I bumped the strictly regulator to 65 cold, and after about 10 min of idling, it was down to 60 at idle. Getting on the highway light throttle drops to 55 or so, cruising at 70 with slight throttle to keep speed, its at 58ish, apply some throttle to maintain on slight hills, down to 50....

Guess im calling air dog tomorrow :fustrate:

6.0 Tech · Sep 3, 2016

So talkd to air dogs tech guy today, and didnt get really any run around surprisingly. Was just told to check pressure directly at the pump to verify the drop was from the pump and not the strictly regulator. Checked that, found the pump is the issue, and when i called back, couldnt get ahold of anybody. Figure they must have closed early for the holiflday weekend. So hopefully it dont fully chit itself this weekend before i can get some warranty stuff figured out.... :doh:

nighthawk285 · Sep 8, 2016

Did you get it warrantied out? I had the same experience with calling them in that they didn't give me any run around. I had already read through a bunch of test procedures and had let them know I already performed those, and they sent me a new 4G unit that same day. Mine had just flat died on the way to work one morning, and I had only bought it 2 1/2 months prior.

6.0 Tech · Sep 8, 2016

Called them back on Tuesday, they warrantied it out really no uestions asked after I gave them the test results. Waiting on it to show up at this point, they did warranty it out with the 4g, so that should be good.

nighthawk285 · Sep 8, 2016

It was pretty amazing the difference between pumps with mine. The original one was super loud from day 1.....this one is as quiet as can be.

6.0 Tech · Sep 8, 2016

mine was pretty loud, then quieted down. I haven't heard it for probably 8 months or so now. before I could hear it inside the cab with the windows up and ac on.

nighthawk285 · Sep 8, 2016

Yep that's how mine was. Even with an upgraded draw straw. Then one day on the way to work it went silent and my FP quickly dropped to 0.

6.0 Tech · Sep 8, 2016

I had the relay uit on me back in p]November or December, which is why I wired it to the factory wiring, well that and I wanted to clean up the wiring mess I had some. But it was pretty quiet before that as well. well ***, that has been 9-10 months ago, I guess it got quiet before that. probably about 4 or 5 months after I installed it. But fuel pressure didn't start dropping till recently.

6.0 Tech · Sep 15, 2016

Ok, little update. Pump was warrantied out no issue, got it on the doorstep monday. Got time and put it in today at work, wasnt too awful hard but made a hell of a mess. Turns out my pich off pliers needed a zip tie to hold them closed :doh:. After gettin the pump in it took forever to prime, which i thought was weird as i didnt really lose too much fuel out of the separator. I ended up turning.the.pump on for about 5 minutes to finally build pressure. After bleeding i took it for a ride.

What was set as 65 psi at idle is now 70, but all the.way up to 95 getting on the highway it held about 68 psi. Im happy to say the.least...

Side note... Anyone know.what pressure the injector o rings are good to? Kinda worried about the morning, where pressures have typically been about 5 psi higher lately, im assuming.due to cold fuel. Is 75 gonna blow one out, or will i be ok?

Thanks :thumbsup:

nighthawk285 · Sep 16, 2016

75 seems to be the upper limit on what those o rings reliably hold to for most folks, although some have reported they leave theirs up around 80 without much issue......I keep mine at 65.