Air Dog Installation

[Monkey Run]

Originally Posted by hookupandgo

This is a false statement. There are others that have done this and had problems. You cannot "share" the CAPS pump return line when using the FASS, you need to run its own. This is one reason I went with the AD. You have to dig deep in all the forums but you will find some that have had "codes" thrown when using the CAPS return with a FASS.

On another note, one thing i love about the AD (FASS would be the same) -- I ran the line for a pressure gauge -- is seeing the pressure build. I have seen cases when I would go to start things up after sitting a while and it would take many seconds before full pressure is reached. The "wait" light is out but still now pressure. Wait a few/10 seconds more and bingo, pressure and she fires right up. Before I would crank, turn off so the lift pump would run again, crank again and then she would fire. So run the extra gauge wiring -- very nice to have and know the pressure is in the line.

I am running a gauge line, and the FASS has a fitting built into the pump manifold. The pump model I am using is new, it does not require a separate return line, clearly stated in both the literature and by the FASS engineer I personally spoke with on the phone. In fact, the return line is quite small, and is supplied with the kit. According to the engineer, the only thing returned on that line is the air which is extracted during the recirculation process (the pump will recirculate excess fuel through the filters) and a small bit of fuel. In essence, it's a copy of the AD.

[hookupandgo]

Ah... Interesting that they made that change. That definitely can be advantageous. While reading your responses i was thinking exactly what you said -- kinda a copy/migration to what the AD does.

Either way, i really like the concept and function of these pumps.

[Monkey Run]

I need to tie into the return line, does anyone know what this fitting is ie size type? It's the fitting closer to the engine on the return side of the lift pump fuel block. As for the intake, I am going to attempt to fit it to the primary filter directly. Thank you!

[RockyCliff]

Here's a pic of my return line plumbing. I purchased the complete kit from AD which included the tee to use on the lift pump manifold return side. On mine it's the line closest to the block and while the fitting in the manifold itself is metric/o ring it had a metric to JIC fitting there to connect to a #8 JIC swivel. I simply inserted the tee in between the manifold and return line. It was no small feat physically getting to it on my coach however.

Hope this helps.
Cliff
2001 Endeavor

[Mile Marker 42]

Originally Posted by RockyCliff

Here's a pic of my return line plumbing. I purchased the complete kit from AD which included the tee to use on the lift pump manifold return side. On mine it's the line closest to the block and while the fitting in the manifold itself is metric/o ring it had a metric to JIC fitting there to connect to a #8 JIC swivel. I simply inserted the tee in between the manifold and return line. It was no small feat physically getting to it on my coach however.

Hope this helps.
Cliff
2001 Endeavor

Interesting. I went with AirDog pump only and bypassed my lift pump but retained the factory return line.

[Monkey Run]

Cliff,

I suspected metric, as the part of the fitting closest to the fuel block would not fit to an SAE open end wrench. The return line fitting itself, however, is 5/8, so most likely, mine is the same as yours. FASS sent a fitting along with the kit but it's smaller, the collars are 7/8". The picture does not show the outlet, however, there are female threads for a fitting. You don't happen to have the part number do you?

[mackwrench]

Originally Posted by Mile Marker 42

Interesting. I went with AirDog pump only and bypassed my lift pump but retained the factory return line.

Same here....I used airdog raptor pump, used OEM primary and secondary filter setup...and same return line.

[lbw6303]

I refer you to a thread that ran under a title of something like --- 2004 Monaco Cummins 350 Isc Cummins engine stalls and then heals overnight ".
This was back in 2020 with much help from this forum. I provided a complete summary when the problem was solved with a FASS system. Importarightntly, the root cause seems to be that the " sucking of fuel" by the injection pump, through at least 3 low pressure connections allows air to be sucked in causing "Foam' to be provided to the injection pump. A pressure sensor ultimately shuts you down to save the pump. Over night, the air works its way out of the fuel. The engine starts right up and you can run just fine until it happens again. My 2nd stall showed the primary filter half full of air as tho I was out of fuel. This is a chronic problem with older rigs and I think Cummins knows exactly what causes it. The NTSB should force a recall on these units. Rework the low pressure connections at the primary filter ( 2) and at the input of the lift pump. That alone should fix the problem ( stop the air from getting in ). My fix included FASS , with a gage on my dash, a replaced fuel supply line ( unnecessary ), and leaving OEM lift pump untouched, even tho un needed. FYI lbw6303.

[Mile Marker 42]

Originally Posted by lbw6303

I refer you to a thread that ran under a title of something like --- 2004 Monaco Cummins 350 Isc Cummins engine stalls and then heals overnight ".
This was back in 2020 with much help from this forum. I provided a complete summary when the problem was solved with a FASS system. Importarightntly, the root cause seems to be that the " sucking of fuel" by the injection pump, through at least 3 low pressure connections allows air to be sucked in causing "Foam' to be provided to the injection pump. A pressure sensor ultimately shuts you down to save the pump. Over night, the air works its way out of the fuel. The engine starts right up and you can run just fine until it happens again. My 2nd stall showed the primary filter half full of air as tho I was out of fuel. This is a chronic problem with older rigs and I think Cummins knows exactly what causes it. The NTSB should force a recall on these units. Rework the low pressure connections at the primary filter ( 2) and at the input of the lift pump. That alone should fix the problem ( stop the air from getting in ). My fix included FASS , with a gage on my dash, a replaced fuel supply line ( unnecessary ), and leaving OEM lift pump untouched, even tho un needed. FYI lbw6303.

I could buy that. Was it someone on this thread who said air is coming through the lift pump gasket? I believe this as well. Definitely think if you own an ISC, it is in your best interest to install a Fass or AirDog.

[RockyCliff]

Macwrench,

The pic I posted just was work in progress showing the return tee arrangement. The hose "hanging down" is the OEM fuel supply inlet hose, which has a #10 JIC swivel fitting. Like most others I bypassed the lift pump. On the outlet side, not shown in the photo, there was a steel tube line going up to the secondary Cummins filter. I removed the OEM steel line and had a new hose made and coupled it to the OEM supply line shown hanging down in the pic and connected it to the secondary filter inlet. I caped the inlet and outlet of the lift pump and installed the relay to "fool" the ECM during the programed prime cycle.
I also installed a Glowshift fuel pressure guage in the dash with the sensor mounted in the fitting on top of the Cummins secondary filter head. I say all this as I am not sure what "part number" you are asking about. The fitting you show in your pic was not changed by me, I just left them in the manifold and capped them off.

So far I have about 5k miles on my system. Starting is easier, idle is smoother and quieter, accelertaion better and so far my fuel mileage looks to have improved, maybe 0.5 mpg better, although I admit I did not have a good baseline of data to start with.

My decision to go AD vs FASS was primarily around the fuel return systems each used and the factory direct support I got from AD. I live in a rural small town area and the closest local diesel performance shop who is the FASS dealer was not too familiar with the larger truck and RV applications. From all I have seen on this forum you can't go wrong with either supplier.

My install basically followed Arkansas RV's direction/method as well as all the other good advise provided on this forum for which I am very appreciative.

Cliff

[mackwrench]

Cliff, wasn't me looking for a part number?

But your set up looks good, and no doubt this is one of the best upgrades for an engine with CAPS system.... however it's plumbed now has fuel "pressure" to the injection pump vs the vacuum suction it used once the OEM lift pump switched off.

I have a few thousand miles on mine, no issues.. and while I don't have any changes in mileage or power, it now starts right up with little effort.

I wanted to keep my fuel filter set up, I use a Davco primary filter.
Only thing I did different was to leave the OEM lift pump in. I had just replaced it a few months before, I put the airdrog in between the lift pump and the secondary fuel filter. ....so I'm not pressurizing the lift pump. It's still connected to ECM and runs when key on.

Now if I had a older, leaking lift pump, I'd bypassed it.
Attachment 381181

[Monkey Run]

Originally Posted by RockyCliff

Macwrench,

The pic I posted just was work in progress showing the return tee arrangement. The hose "hanging down" is the OEM fuel supply inlet hose, which has a #10 JIC swivel fitting. Like most others I bypassed the lift pump. On the outlet side, not shown in the photo, there was a steel tube line going up to the secondary Cummins filter. I removed the OEM steel line and had a new hose made and coupled it to the OEM supply line shown hanging down in the pic and connected it to the secondary filter inlet. I caped the inlet and outlet of the lift pump and installed the relay to "fool" the ECM during the programed prime cycle.
I also installed a Glowshift fuel pressure guage in the dash with the sensor mounted in the fitting on top of the Cummins secondary filter head. I say all this as I am not sure what "part number" you are asking about. The fitting you show in your pic was not changed by me, I just left them in the manifold and capped them off.

So far I have about 5k miles on my system. Starting is easier, idle is smoother and quieter, accelertaion better and so far my fuel mileage looks to have improved, maybe 0.5 mpg better, although I admit I did not have a good baseline of data to start with.

My decision to go AD vs FASS was primarily around the fuel return systems each used and the factory direct support I got from AD. I live in a rural small town area and the closest local diesel performance shop who is the FASS dealer was not too familiar with the larger truck and RV applications. From all I have seen on this forum you can't go wrong with either supplier.

My install basically followed Arkansas RV's direction/method as well as all the other good advise provided on this forum for which I am very appreciative.

Cliff

Cliff, twas I looking for the tee part number from AirDog so I could order it. I'm going to bypass the lift pump but the fuel block will remain intact. So the tee fitting has to attach to the fuel block on one end and the existing CAPS return line on the outlet side.

[Monkey Run]

At this point, I believe I have ordered the correct fitting to tie the FASS in at the return line fitting where it meets the fuel block. Unfortunately, these fittings are not available anywhere near where I'm performing the work, so hopefully the size is correct this time as it takes a few days to receive them (10an to 6an with gauge fitting).

[RockyCliff]

Hope youn get the correct tee. I had typed a response earlier to you on this but it didn't seem to post. In summary I said my tee came with the AD kit I purchased and had a barbed hose fitting for connecting the AD return line. Looks like the FASS return is a #6 JIC/AN fitting.

Cliff