Airdog Installation

[Meames1]

I installed an Airdog Heavy Duty system to my '99 American Dream to replace the weak-link factory lift pump. Much info on here and elsewhere as to the shortcomings of the Cummins ISC CAPS injector pump, so I'm trying to help extend the longevity.

After much research I decided on the Airdog Heavy Duty setup built for over the road heavy trucks. I'm not looking to debate Airdog vs others, this is the choice I made and am very happy with it. Any aftermarket pump that runs full time or as needed will be a huge upgrade to the factory lift pump and limited run time during startup only. I will say this isn't the cheapest alternative, but I just felt it was the better option for me.

The purpose of this thread is to show how i installed it on mine to help others decide what's best for them.
Mine is a 1999 American Dream built on a Spartan MM Chassis.
My setup included, 10AN hose from tank to #1 filter, 10AN hose from #1 filter to factory lift pump, 10 AN hard tube to #2 Filter, 10 AN hose from #2 filter to CAPS pump, 8AN hose (return) from factory lift pump back to tank.

Seeing they don't make an RV specific kit I used part #A3SPBT404, this is made for a Cummins N14 with a remote mount filter. All the fittings included for this application "could" have allowed me to install it without any additional parts. However, I decided to remove some 8' of hose that I didn't want to loop around so I bought some new hose and fittings for about $70.
I added a liquid filled gauge to measure fuel pressure that I already had laying around. Eventually, I'll probably install an electric pressure gauge and run it to the cockpit...but that's an off-season project .


I attached the pump to the frame next to the engine in a spot real easy to get to for filter replacement. They sell a sandwich style bracket kit that would allow installation without drilling. I just drilled my frame for the 3/8's bolts as there was nothing behind it and access was easy.






I decided while I was here that I would move the #2 factory filter assembly to outside the frame next to the new pump. As many are aware, this filter from cummins is mounted on the engine block between the lift pump and CAPS injection pump. It's somewhat hard to get to as it's above the starter and tends to make a mess during replacement. Also, the battery cables to the starter are close. Now it will be much easier to replace.
The "S" shaped line was the original line used by Cummins between the lift pump and filter, made it easy to just reuse it.
I made a new 10AN line from the (now #3) filter to the CAPS pump.







I capped the original lines in and out of the factory lift pump with 10AN caps.
Also installed the supplied 8AN "T" with 6AN fitting to the factory return line out of the factory lift pump manifold. Fabricated the new 6An return line included in the kit and attached it from the Airbog return to the new "T".






I ran the supplied wiring harness (very nice quality btw) from the pump into my BCC. Attached the relay to the back wall of the BCC and hooked up the hot and ground directly to the battery. The trigger wire was hooked to a key-on tap in the BCC fuse panel. Easy peasy




I now have a 10 micron water separator, into a 6 micron filter and finally to a 2 micron filter. Technically I didn't need the 3rd filter, but I felt why not filter it once more to a smaller micron capacity while I have the positive flow. Fires up and sounds great, haven't driven it yet, so I'll update after some miles with any noticeable differences. Good Luck !

[imnprsd]

Meames1: Very nice write-up! Great pictures with excellent intro...

Question: Is that Filter #33422 your #1 filter or your #3 filter? ...What micron rating is it? ...I'm asking because I see you mounted your liquid fuel pressure gauge on top and I don't know if that's the suction side or the pressure side?

I agree: No need to discuss which pump is better from a functional point of view. Both AirDog-II-4G and FASS-TS pumps will provide positive fuel pressure to your CAPS or HPCR injection pump to protect it from premature failure, due to lost lubrication when back in 2006 they switched to USLD fuel at the pump; and without any air in your fuel lines your injection system and injectors should run smoother.

I presume you disconnected your lift pump wires to your ECM and added a "dummy relay" to keep your Check-Engine-Light (CEL) from coming on? ...But maybe you found that wasn't necessary? If so, please let us know that too!

FYI, I talked with a AirDog-Pure Flow tech and he said the AirDog pump will only return 3/4-1 gallon/hr of fuel. So that's why you can "T" into your CAPS return fuel line without any problems. ...That's not possible with a FASS-TS filter system. And this tech told me the AirDog Pump will produce 25PSI on the pressure side, so can you confirm that's what you are getting... or is that sensor to your AirDog pump used to trip a dash LED warning light at 5PSI (or is it 10PSI) to signal it's time to change your filters?

Where did you buy your those 10AN-Caps to your Lift Pump Manifold; and your other fuel fittings?

I also like that "S" Metal Fuel Line between your filter and the AirDog Pump. Did you make it or order it?

OTHER COMMENTS:

* Some owners have reported they added a ball valve before the #1 filter so they can shut the fuel line off when changing filters. Apparently, this makes changing filters easier and less messy, because filters in a filter bay are located at a relatively low position vs the fuel tank.

* Using an oil filled fuel pressure gauge is a good way to go, but no one has posted the hardware needed to read the pressure gauge from inside the filter bay. Since you said you you will be addressing this in your next post, please share some pictures on how you accomplished this: a) Using a 90-degree gauge, b) using 1/8" npt brass fittings, or c) adding a flexible fuel line?

Note: I added an digital gauge I can read near my dash, but after the first 1,000 miles I don't pay attention to it any more. So a $25 liquid fuel pressure gauge mounted on the fuel filter sounds like a good plan everyone should do; as this information will come in handy in the event of a no-start condition that usually boils down to either a fuel delivery problem or an electrical problem.

[Old Scout]

Curious--basic problem with the OEM lift pump is that the manifold gasket leaks--fuel out and air in....seems you would want to by-pass the left pump entirely when installing the new pump system ??????

[imnprsd]

Old Scout: I'm pretty sure the OP disconnect the electrical wires from the lift pump to the ECM. I hope so anyway, because with out any fuel passing through the carter-style lift pump I would think it would burn up at some point since fuel flow is the the only lubrication and cooling method for the pump.

Let's see what Meames1 says about this and about the order of his fuel filters, because fuel should be flowing direct from the the Tank ==> AirDog #1 & #2 filters ==> #3 filter ==> CAPS gear pump.

Note: In my FASS installation I did NOT bypass the inlet side of the Lift Pump Manifold, but I did disconnect the wires from the LP to the ECM so it will not turn on. That was 8,000 miles ago and I have had zero problems.

I also paid Freightliner $350 to disconnect these wires, because they were hard to get to and I did not feel comfortable yanking on wires above my starter -- working blind. But in hind sight, I wish I knew I could just add a $25 delay-on-relay for 30s-60s and I would have left my lift pump "as-is" and the ECM wiring to the LP "as-is" too. That would have saved me $325 and 1 day of to and working with Freightliner.

Note: Everyone says you need to by-pass the lift pump (fuel lines and electrical connections) and I do think it's good idea, but in reality you don't.

The good news is that both FASS-TS and AirDog-II-4G pumps have evolved to be very reliable pumps, but that doesn't mean they don't fail. So I have a back up lift pump system in the event my FASS pump fails. Do I need it? IDK. Maybe one day. ...but probably not.

My advice is to go with the least expensive installation and that might mean AirDog-II-4G or FASS-TS; and that is dependent on your chassis type, location of your filter, ease of access to the top of your engine and fuel tank (or not), and if you are paying a mechanic or doing the install yourself.

And what we know know it that installing either an AirDog or a FASS pump is not that hard once you see how other people are doing it! So thank you Meames1 for sharing your experiences with others!

I think everyone with a CAPS should be installing an AirDog-4G or a FASS-TS if you have more than 50,000 miles on your coach or plan to some day. And now that pump prices have dropped, and you can come up with you own installation plan, for your chassis, I think the more people will buy one of these aftermarket pumps!

[Meames1]

Originally Posted by imnprsd

Meames1: Very nice write-up! Great pictures with excellent intro... Thanks.

Question: Is that Filter #33422 your #1 filter or your #3 filter? ...What micron rating is it? ...I'm asking because I see you mounted your liquid fuel pressure gauge on top and I don't know if that's the suction side or the pressure side? The Wix 33422 is a 2 micron filter and is the 3rd and final filter before the CAPS. The gauge is on the pressure side.

I agree: No need to discuss which pump is better from a functional point of view. Both AirDog-II-4G and FASS-TS pumps will provide positive fuel pressure to your CAPS or HPCR injection pump to protect it from premature failure, due to lost lubrication when back in 2006 they switched to USLD fuel at the pump; and without any air in your fuel lines your injection system and injectors should run smoother.

I presume you disconnected your lift pump wires to your ECM and added a "dummy relay" to keep your Check-Engine-Light (CEL) from coming on? ...But maybe you found that wasn't necessary? If so, please let us know that too! I installed a relay to fool the ecm.

FYI, I talked with a AirDog-Pure Flow tech and he said the AirDog pump will only return 3/4-1 gallon/hr of fuel. So that's why you can "T" into your CAPS return fuel line without any problems. ...That's not possible with a FASS-TS filter system. And this tech told me the AirDog Pump will produce 25PSI on the pressure side, so can you confirm that's what you are getting... or is that sensor to your AirDog pump used to trip a dash LED warning light at 5PSI (or is it 10PSI) to signal it's time to change your filters? Yes, I'm seeing 25 psi. My warning light is the standard 5psi setup they ship with the pump. At this time I just mounted the warning light in my battery bay. I'll save running wires to the front for the off season.

Where did you buy your those 10AN-Caps to your Lift Pump Manifold; and your other fuel fittings? All fittings etc I buy from Summit Racing...I actually had the caps (and the gauge), old race car guys never throw anything away, lol.

I also like that "S" Metal Fuel Line between your filter and the AirDog Pump. Did you make it or order it? That's the factory line between the stock lift pump and block-mounted #2 filter, repurposed.

OTHER COMMENTS:

* Some owners have reported they added a ball valve before the #1 filter so they can shut the fuel line off when changing filters. Apparently, this makes changing filters easier and less messy, because filters in a filter bay are located at a relatively low position vs the fuel tank. I thought about this also and if I had one during the install I would have and it's a good idea.

* Using an oil filled fuel pressure gauge is a good way to go, but no one has posted the hardware needed to read the pressure gauge from inside the filter bay. Since you said you you will be addressing this in your next post, please share some pictures on how you accomplished this: a) Using a 90-degree gauge, b) using 1/8" npt brass fittings, or c) adding a flexible fuel line?

Note: I added an digital gauge I can read near my dash, but after the first 1,000 miles I don't pay attention to it any more. So a $25 liquid fuel pressure gauge mounted on the fuel filter sounds like a good plan everyone should do; as this information will come in handy in the event of a no-start condition that usually boils down to either a fuel delivery problem or an electrical problem.

Thanks for the comments.

[imnprsd]

Meames1: Thanks for the additional information.

I checked the filter specs for that Wix Fuel Filter #33422. I found out it is a water separator and since you already have a couple water separators, did you choose this one because you wanted to keep your Water In Fuel (WIF) sensor connected to it... and you wanted 2-micron filtration on the #3 filter?

I choose this filter combination with my FASS Pump:


Here's my graduating filter sequence:

#1 Filter ==> FS-1242 (20-micron) and the plastic bowl is #3831871S.

#2 Filter ==> FS1022 (10-micron with Water In Fuel (WIF) Sensor), this sensor port is oval shaped (M14 x 2.0) - if square shaped sensor port required, use 33604

#3 Filter ==> FF5320 or FF5324 or Baldwin BF7633 or FASS-3003 (3-micron)


Note: Everyone needs to know you can't judge a filter by it's micron rating alone. And in general, I have found, what Fleetguard calls their 10-micron rated filter @ "Absolute" ==> Napa, Wix, and other call it a 5-micron filter and do not specify how they take their measurements.

Also, Cellulose filters can break down after 1 year depending on the acidity of the fuel in the tank. And when a filter breaks apart inside that material can end up in your injection pump. Or to be more specific, in a CAPS system your gear pump has a 10-micron metal screen in it and should trap this debris... but then you will have fuel obstruction issues.

This is why all the manufactures recommend changing fuel filters every year, but I think that's "overkill". I choose to replace mine every three years... and after I pick my RV up from storage...at the start of the 3rd year... I change to new filters after I drive the coach for 1-4 hours.

What you do with your fuel filters is up to you! ...And there is no reason to prime the filters with diesel since you have an electric lift pump. Just turn the key on 3x for 30 seconds each and your ISC/ISL will self prime the filters and you will not end up with an air lock.

TIP: I installed a fuse next to my FASS pump so I can use it like a switch (on-off) to help prime all 3 filters at once. To do this you install filters #1 & #2 tight, but leave filter #3 loose. Then tap the fuse to start the fass pump ... and let the air escape out of the #3 filter.

...And when you see fuel ooze out of the the #3 filter seals... disconnect the fuse to cut power to your FASS or Airdog lift pump, and then just tighten filter #3. Now start the engine normally.

===

Note: FASS does not recommend using anything smaller than 20-microns on the suction side filter (#1).

I'm guessing AirDog-4G pumps don't car about this 20-micron rule, because they ship their filter-kit with smaller filters in the first place. (I think.)

I also used the FS1022 (Water Separator + WIF) as my #2 filter, but I did not want to go smaller then 10-microns in my #2 filter position.

Final comment: Fuel filters are so much cheaper on Amazon, so plan ahead and save $$.

[Arkansas RV]

Meames, great write up and pictures. That’s not my forte. I will be interested in what pressures you run at idle and going down the highway. Clean looking setup.
I would also be interested if you feel a bit of a power gain, especially on hills and engine response as I did?

[Meames1]

Originally Posted by Arkansas RV

Meames, great write up and pictures. That’s not my forte. I will be interested in what pressures you run at idle and going down the highway. Clean looking setup.
I would also be interested if you feel a bit of a power gain, especially on hills and engine response as I did?

After running a while I noticed the fuel pressure at about 30-32 psi. I could not adjust it any lower. I called Lance @ Airdog (Excellent customer service !) and had him overnight their lightest regulator spring. After install, the pressure dropped to 15 psi with the regulator turned all the way out. I adjusted it to run right at 20 psi. Between this pump and the AG diesel programmer, I have all the power I need. I'm quite impressed, we went camping last weekend over lots of long grades and it pulled them with ease. I only bought this rig in October and had a few small trips so I don't have a bunch of "pre-modification" history, but I'm very happy on how it runs now.

[Cclark746]

So I just picked up a ts fass 100 gph I was told that should be plenty of fuel for my isl 8.9 400hp Cummins. Is this correct? Also what relay is used to fool the ecm on the factory pump and how is it wired up? I’m planning connecting the inlet and outlet of the factory lift pump and replacing the first filter with the pump. Then running a separate return line and tee it into the vent line. Does any one see any issues with my installation? Should I run a 10, 5 or 2 micron filter as my 3rd? Is the caps return separate from the stock lift pump? Thanks sorry a out all the questions.

[Pillbox]

Very nice write up, thanks
Terry

[Arkansas RV]

Great to hear, and thanks for the feedback.

[Arkansas RV]

Originally Posted by Cclark746

So I just picked up a ts fass 100 gph I was told that should be plenty of fuel for my isl 8.9 400hp Cummins. Is this correct? Also what relay is used to fool the ecm on the factory pump and how is it wired up? I’m planning connecting the inlet and outlet of the factory lift pump and replacing the first filter with the pump. Then running a separate return line and tee it into the vent line. Does fany one see any issues with my installation? Should I run a 10, 5 or 2 micron filter as my 3rd? Is the caps return separate from the stock lift pump? Thanks sorry a out all the questions.

Clark
When you say tee into vent line, are you meaning at the tank? If that’s correct then no problem. You can’t tee into the Capps return line at the lift pump manifold with a Fass pump. If you run pressurized fuel thru lift pump, again no problem. If you bypass lift pump Then cap in and out fittings. Filter size is up to you; I run a 10 micron filter> then 6 micron> then 2 micron.
Any relay for fog lights etc will work. Check any of the posts on Fass or AirDog for the details you want.

[rECUpirate]

Originally Posted by Meames1

I decided while I was here that I would move the #2 factory filter assembly to outside the frame next to the new pump. As many are aware, this filter from cummins is mounted on the engine block between the lift pump and CAPS injection pump. It's somewhat hard to get to as it's above the starter and tends to make a mess during replacement. Also, the battery cables to the starter are close. Now it will be much easier to replace.
The "S" shaped line was the original line used by Cummins between the lift pump and filter, made it easy to just reuse it.
I made a new 10AN line from the (now #3) filter to the CAPS pump.

Meames1, thank you for sharing this. After a bit of run time under the belt do you have any follow-up comments? Any issues noticed with putting the AD and filters right next to the hot muffler and exhaust? I have always wanted to relocate that filter in there but had some techs caution against that location because of the heat of the exhaust. Not sure if they just didn't want to do the work.

[Meames1]

Originally Posted by rECUpirate

Meames1, thank you for sharing this. After a bit of run time under the belt do you have any follow-up comments? Any issues noticed with putting the AD and filters right next to the hot muffler and exhaust? I have always wanted to relocate that filter in there but had some techs caution against that location because of the heat of the exhaust. Not sure if they just didn't want to do the work.

No issues what so ever. Several thousand miles since install and every trip I feel it runs better and better. I'm sure that's just me, but I'm very happy with the decision to install the unit.
Also, IMO, mine is really not that close to the exhaust. Sure, on same side of engine, but there is close to 12" of clearance.