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Air Dog Return Spring Shim


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Hello all,

 

I'm new to this forum and have already found a wealth of information.

I have an Air Dog FP-100 on my '01 Dodge Ram 2500 QC with the standard power Cummins. It has just failed the Air Dog pump for the 3rd time, this time costing me a new fuel injection pump. The gearotor/motor assembly was just installed in Sept.

I put in the new fuel injection pump and everything tested fine. I knew the Air Dog was not putting out as much pressure as I would like, so before I ran the truck further than a couple miles, I installed a 1/4" washer that I drilled out to 3/8" ID and then shaved the OD to fit under the return to tank fitting in the Air Dog base.

I drove the truck about 35 miles and then I installed a new 10 micron fuel filter. On the return trip home the truck started acting like it was starving for fuel and the injection pump was dying again. I managed to limp it home.

I put my test gauge on the fuel line (the sending unit for the gauge on my dash is dead) and at idle I'm getting just under 8 psi, as I throttle up the gauge drops to zero. I called Air Dog, and once again, they are sending me a new gearotor/motor assembly.

I also purchased a new sending unit for the FP gauge on my steering column, and a new test gauge for verifying. They should be here about the same time the new Air Dog pump gets here.

 

I would like to know if you have to put more than one washer under the spring in the return to tank fitting to increase the pressure above 14.5 psi? I only installed the single washer, should I add another one? My average reading at idle with a pump that's not jacked up is 13 psi, but I'll have to get the new pump installed and re-verify everything again.

 

The original Air Dog was installed in '07 and failed in Feb. '11. That one failed in Sept. '13 and the first gearotor/motor assembly they sent me didn't pump at all. They sent me a second unit and I verified it was working with a bucket flow test. I even changed out all my fuel lines when I installed this second pump, thinking I might have a blockage but found none. This is the one that has failed now, after only 4 months. Needless to say, Air Dog is not my favorite company right now. I'm very close to just installing a FASS and once I get the new pump put on, sell the FP-100 to recover some of the cost of the new unit.

 

Any ideas on why I'm failing so many Air Dogs? Should one washer be enough?

 

TIA,

Elkaholic

 

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Sad to say I've got a phone call of a gentleman back east that just lost his 4th AirDog in one month time frame. So each one lasted about 1 week a piece. The last one barely made 100-120 miles I was told. Since he's strapped for cash so he's going back around for another warranty pump number 5. Ugh.

 

Such a wonderful product but total junk now. Reminds me of the vBulletin threads I read...

 

http://www.theadminzone.com/forums/showthread.php?t=106727

 

http://www.theadminzone.com/forums/showthread.php?t=106441

 

Now you know why I swapped forum software. But Like as you read the older AirDog's like mine are like the older vBulletin 3 software rock solid and still working. Strange but true...

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Ahh yes, now I remember why I quit spending time on forums, a half dozen replies and not a single answer to the original question of "should it take more than one washer to shim the spring under the return to tank fitting to raise the pump output pressure noticeably?"

Not sure a new FASS system is in the budget right now, but a possibility. First thing is to get the new gearotor/motor assembly in my hands and bolted in place. What I see for output flow and pressure will be a major determining factor on buying a FASS right away.

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Thanks Michael, I'm hoping my new sending unit gets here for my FP gauge on the steering column. I'm not sure how much I trust my old test gauge. I bought a new test gauge too , but I bought it from Geno's Garage and when I spoke to them yesterday the lady said the Atlanta area has come to a halt because of the weather. She said it looked like UPS was shut down. Hopefully it will get shipped today and I'll have it by Saturday.

I'm going to fabricate another washer so it's ready when I get the new Air Dog pump installed.

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So, here's the update on this. I installed two washers under the spring in the return to tank fitting and also put in a new sending unit for the Auto Meter gauge on the dash so I can now actually see what my pressure is.

With the old pump it would make 16-17 psi at idle, and drop to as low as 10-11 psi under throttle.

 

I received the new gearotor/motor tower assembly today and installed it. While I had the pump out on the bench, I noticed the pre-filter screen at the inlet to the water separator had some debris clogging the screen. I cleaned it thoroughly and installed the new tower assembly. It now makes 17-18 psi at idle, and stays above 15 psi under throttle.

 

I'm satisfied that it is working correctly, and to verify my pressures, I also received my package from Geno's Garage with a new Test Gauge. There is a 2-3 psi difference between the in-cab Auto meter and the Test Gauge, but they are both within the range I am looking to maintain, above 14.5 psi under throttle to keep flow past the computer on the VP-44.

 

Thank you to the members here that helped me out with advice and recommendations, especially Mopar1973Man.

 

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Elkaholic,

 

I have the FP-80 and have had it on the truck for around 7 years.  Before that it was on a buddies truck for who knows how long.  I have not had any problems with it and have only changed the filter every 20k.  I do not have any gauges,  but recently I can hear it running and it seems as if it is surging maybe.  I was unaware of a screen on the inlet side and unaware of putting washers in the return to tank fitting.  Is this something I should be aware of? 

 

Thanks,

Luke

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Luke,

 

I learned about the washers under the Return To Tank fitting here on the forum, Mopar1973Man had mentioned it. Basically there is a ball-check under the return to tank fitting, and if you make it harder for the ball to move and open the line, your pump will send more pressure to the injection pump. My FP-100 indicates that it is pre-set at 15 psi, but it never did any better than 13.5 psi or so. I put two 1/4" washers between the fitting and the spring and my pressure going to my injection pump is now 17-18 psi. I used a 3/8 drill to open up the innerr diameter of the washers, then took them to my belt sander and reduced the outer diameter so they fit in the port.

 

The screen is the first thing the fuel goes through when it enters the Air Dog, it is in the nipple that the water separator screws on to. You can remove the water separator and unscrew the nipple with a deep-well socket or crescent wrench. It is held in the nipple with a star washer that is compressed into the edges of the nipple. I pulled the star washer out with a jewelers screwdriver and put it back in by hitting a socket with a hammer. Unless it is really loaded up with stuff, I recommend just blowing it out with air if there's anything in there. Mine had quite a bit of fiber debris around the edge so I took it all the way out.

 

As far as not having a gauge, you can find enough horror stories on the web about lift pumps and Air Dogs failing to keep you reading for a year. If you are running a VP-44 fuel injection pump in a pre-2003 Dodge Ram you really should be monitoring your fuel pressure to the injection pump. Dodge says anything under 5 psi can kill the FI pump, but I start to worry if it goes below 8 psi. You can get a gauge, or they have a warning light kit at Geno's Garage you can install that will go off at 5 psi.

 

For the money you spend on the gauge, it's still way cheaper than what it costs to replace your fuel injection pump. If it's just the injection pump, the cheapest I've found is $990 plus the core. If you have to add the lift pump or Air Dog too you're looking at another $350 to $590, and that is if you do the work yourself.

 

I got lucky, my Air Dog is under their Lifetime Warranty so they shipped out a new pump/motor tower assembly for nothing and I found a used VP-44 for $500. I installed them myself. The downside is that I didn't purchase a reman'd pump, so there's no warranty on it.

 

If you want to put a gauge in and have the time to comparrison shop online, try Geno's Garage out of Georgia, Alligator Performance out of Idaho, and Kens Performance out of California. I've purchased things from all of them and I can personally attest to the excellent customer service you will get from Geno's and Ken's.

 

I should also say that you could support one of the Sponsors of this forum and buy from them also, I just haven't used any of them myself.

 

Elkaholic

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Elkaholic,

 

Thank you for your response:)  I pulled the water separator off and removed the nipple that it screws on to and there is nothing in it.  It is just an open hole.  I wonder if they added that to the fp-100 and later models.  I have not had a chance to loo at the return line shims yet.  you are correct and I do need to get some gauges for my truck.  I have been meaning to but just like other stuff things get pushed aside and forgotten about. I was going to mention too that I did have the fuel relay go out on my airdog last year.  I just plugged the in-tank pump back in and away I went until I could finally find a new one from air dog.  they had to look in their old warehouse and I got lucky because they said that was the only they could find.  When I installed the air dog I did not remove the in tank pump so it makes it easy to just plug it back in and hook the factory line back in to the injection pump.

 

Luke

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Likeoldfords and Dripley,

 

Yes, I agree, DAP is a good bet and I believe in supporting the businesses that sponsor the forum.

 

Luke,

 

I know what you mean about other things taking priority, it took me 13 years to get the Edge JWA in my truck so I can now monitor the things I need to. I still need to add the TST Products J-hook kit to my turbo waste gate actuator because mine has the solid tube where the boost elbow should go, and I also want to get a High Idle Kit from DAP too. It's only a couple hundred bucks of stuff, but with two kids and all it will take me a few months to get them.

 

When you say the "fuel relay" went out, do you mean the relay for the pump that is mounted to the firewall on the truck and supplies the 12 V power to the Air Dog? If that is the one you mean it should just be a standard relay available at any auto parts store for cheap. Nothing special about them. It's lucky you have the option of going back to the stock in-the-tank pump, when mine died the truck was down for a week waiting on Air Dog to ship out the new tower assembly.

 

Elkaholic

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