of 2017 - 2019 setups. doing some anlisys work on my AFE DS780 setup. the install has sparked my curiosity since I noticed that AFE has changed the install proceedures. initially the install was to connect the lines and the return right at the tank feed and tank return. this is located forward of the fuel tank in the cavity where the transfer case motor is. the new install moves the connections to the fuel cooler . this was a very quiet change. so I drew some pictures to try to figure out what was the pro or con of either. couldnt determine any....BUT...then it occured to me...if you have a S&S DPK or SPE DPK or any DPK that has a return filter...if your after market lift pump can run after the FORD pump primes itself......your adfter market lift pump could push return fuel forward into the system and push the particles your DPK return filter caught back into the CP4 and maybe back into the injectors. scary. so now...the flux capacitor part of my brain is trying to determine if we need a one way check valve in line with our return fuel line to prevent reverse flow in the retun line system.

understand that on a 2017 - 2019 both the stock and aftermarket lift pump will tyrn on and presureize...but the stock one will shut off after the system is pressurized...the after market one will keep runing...push retun fuel back up into the forward system.

Im going to email S&S and see what they think.


maybe this will work

 

Why do you need a second lift pump? The stock one provides more than enough fuel for a stock engine. If installed correctly, the SPE or S&S filter is between the CP4 and the return line at the firewall, before the cooler. Fuel travels about 2' from the CP4 before being filtered.

 

I think it would a more of a potential problem for the 17 plus guys who have an aftermarket pump "after," or closer to the HPFP as it would for the 11 to 16 guys like myself who are (for me, would be) feeding the DFCM primary pump... all my Air Dog would do is feed my factory primary pump with clean, "shined" fuel.... appreciate the heads up though...

I'll have to read my instruction again for the Air Dog but for the return line for the Air Dog, it goes to the fuel tank fill hose through a T fitting...

I'd contact S&S as well as AFE... I have a set of instructions printed out from AFE for the 11 to 16s for their AFE DS780 pump. I'll have to check it out again on their website to see if anything changed...

 

Yes, airdog sends the return fuel to the tank fill tube

AFE sends return fuel to the return fuel junction just forward of the tank.

 

Okay I found my Air Dog info file...

I made a hand drawing of what I wanted to do and what I needed to buy to install my Air Dog WITH the DFCM... I won't take a pic as it will confuse the eff out of people... I'll redraw it before I install and post up in my truck thread...

The old system that was preset at 10 PSI was sold to feed the DFCM that had the requirement of cutting of the fuel tank fill hose with a big tee fitting to return the fuel not used back to the tank. The newer 4G, they now have the 5G system which offers more pressure adjustment by hand with a easy to turn **** on the outside of the pump...anyways, has a smaller tee fitting for the return to plumb into the factory return line as this pump was meant to replace the DFCM but which I am NOT doing... I ordered extra fittings and will post tons of info when it's installed...

The later 4G 165 GPH unit, like the 5G 165 GPH unit for the 11 to 16 trucks is preset at 55 PSI to feed the HPFP. Air Dog sent the 10 PSI spring to me free of charge... I will add a fuel pressure gauge on the supply line between the Air Dog to the DFCM... that way I can get it dead nuts at 10 PSI.

Anyways, I believe the potential problem fritz is describing is for the Alumina Duty guys with an in-tank primary pump which would place the aftermarket pump "after," or closer to the HPFP unlike the 11 to 16 application of a aftermarket pump WHILE RETAINING the factory primary pump (DFCM).

The AFE DS 780 directions for the 11 to 16 application remained the same fritz as they also RETAIN the DFCM pump which their unit feeds.

On page 13, it starts to describe essentially what will be my fuel line connections with my Air Dog... just using the AFE for reference.

https://afepower.com/media/catalog/p...6.7l_td__1.pdf

 

Found this so I can move the afe lift pump return away from the stock return line and move it to the tank fill the same way airdog does it.

no check valve needed.

 

Just to satisfy my own curiosity, I was reading this installation PDF, and the first thought that came to me was "Isn't that exposed to a lot of dirt and potential damage, mounted in a spot that can take rocks thrown from the front tire?". Or, other potential FOD, for that matter.

Seems like if one was to mount that filter assembly that low and on the outside of the frame, that it'd be worthwhile to build some kind of shield around it for protection...

 

I moved mine to the cavity between the tank and the transfer case. I used some electrical u channel, painted it black, and cut the ends to a taper so I can get a socket on the bolts. Socket won’t fit in the uchannel. The bar runs from the transfer case cross member bolt hole indicated in the afe manual to the first bolt on the tank skid plate drivers side. The pump is tucked away nicely.


I had it in the stock position and a rock hit it and cracked my sight glass. Had to pull it off to replace the glass and some other things.

thinking of using a metal collar instead of the upper glass…where it sits now can’t see the glass anyway.

 

I have an Air Dog but I definitely agree with you there for sure... I still haven't decided where I'm gonna mount mine yet.

 

Okay the install I have seen for the Air Dog is that it gets mounted to the inside of the driver's side frame... I had a note I made in the install booklet that said my oil bypass, the FS2500, is even with (mounted by and opposite of) the DFCM. So it looks like but won't know for sure until I'm under the truck that there's room behind or towards the back of the truck on the inside frame to mount the Air Dog...

I also figured out I need one more 90 degree elbow to plumb in the "y" fitting that they include to plumb in the Air Dog return to the factory return... More info along with pics will come once it's installed but the S&S DPK kit has to go in first.


Here's a pic of the fitting that's included to use to replace THE DFCM, which I am NOT DOING, but it will definitely be used to plumb into the factory return line.

More info to come...

 

I removed my pump for now.

I need to get the tube that will let me run the return to the fill hose. I found a supplier for it.

I also need to double check to see if I have fittings to install to the new connect points.

I have the tools to make my own crimp hoses so I’ll be making hoses on the fly.

 

I didn't understand until I saw that diagram. Yeah I'd absolutely put a one-way in the return line between that h fitting and the DPK filter outlet. Better yet would be to have the returns run entirely separate. I don't know how much fuel that Air Dog moves but if it's moving enough into the return than it could effectively dead-head the HPFP return. I think it's doubtful that would actually happen but having the DPK return competing for flow definitely helps nothing.

 

I'll find a video but I don't believe there's not a lot of fuel, from my memory of seeing a video, that comes out of the return from the Air Dog... it's just the fuel not used but I do see the point now though as it would very easy to put in a 1/2 inch check valve into the factory return line... let the conversation continue...

EDIT

Starting at about the 2 minute or so, they show the return fuel flow being dropped back into their demonstration fuel tank.


But truth be told, I am looking into fuel line check valves on Summit Racing and will post more info at one point.

 

Just shot both companies an email on this subject gentlemen...

Okay so now that I'm on board with this and finally see what I didn't before, here's some more info on check valves... because I gotta be honest...

I'm not too keen on throwing on a cheap @$$ Amazon check valve into the mix here... so here's what I came across.

*Russell makes a -8 AN fuel check valve here. they only make it in a -6 AN as another size...
Russell Check Valves

Russell check valves are designed to allow flow in one direction and prevent flow back. They feature a 304 stainless steel check piston that delivers optimum flow with minimal restriction and pressure loss. A positive O-ring seal is incorporated into the high-flow check piston. These valves are ideal for fuel systems due to their low opening pressure of 3 psi.


**Summit Racing -8 AN and -10 AN check valves here.
Summit Racing™ One-Way Check Valves

Summit Racing™ one-way check valves are designed to prevent the back flow of any fuel, coolant, or oils. Their flapper design provides minimal flow restriction, and the high-quality construction of these valves ensures long-lasting performance. Their PTFE flapper requires a low 2 psi to lift off of the seat and is resistant to alcohol, methanol, and bio-diesel fuels. These check valves are offered in a choice of sizes to suit your needs.

A couple of questions were asked about the Summit Racing check valves:

NICK
· 3 years ago

Summit Racing SUM-220194B - Summit Racing® One-Way Check Valves

Will this check valve work with standard american diesel fuel?

DAVID
· 3 years ago

Yes it does. We install them on semi tractors frequently.

Summit Racing SUM-220194B - Summit Racing® One-Way Check Valves

What is the backflow pressure rating as in how much pressure it will hold back before failure? Thanks!

Thank you for your question. The Summit 220194B one-way check valve has an operating pressure range of 5-1500 PSI.

Summit Racing SUM-220194B - Summit Racing® One-Way Check Valves

What is the outside diameter?

Thank you for your question. The Summit 220194B One-Way Check Valves measure 4.00 in. long and have an outside diameter of 1.375 in.


***Redhorse Performance check valves...
Redhorse Performance 4152 Series One-Way Check Valves

Redhorse Performance offers 4152 Series one-way check valves to prevent fuel and oil flow back. Each aluminum check valve is fully fuel and oil compatible and armed with a PTFE stopper. They are available to fit -04 AN through -12 AN fittings with male threads, in your choice of red, blue, clear, and black anodized finishes.


****Fuel Lab check valves here. Again I'm looking at the -8 AN and the -10 AN. I'm thinking the -8 AN will suffice but I'm bringing the bigger -10 size into the conversation.

FUELAB high-flow, one-way check valves are designed to deliver maximum flow with minimal restriction and pressure drop. Featuring -6 AN, -8 AN, and -10 AN male inlets/outlets, 350 gph flow capacity, cross fuel compatibility, and billet aluminum construction, these advanced engineered FUELAB valves allow for easy installation and prevent flow back after pump shut down. The check valves are rebuildable, have fluorosilicone seats and seals, and a maximum pressure rating of 200 psig.



Here's the fittings... to make them work with 1/2 inch fuel hose...

 

You should see if could possibly order an Air Dog "Y" fitting like the one I have and the one shown here to the right in the below picture, for a cleaner install plus the check valve would take care of the potential of your AFE pump back feeding the return line...