FASS Installation on Cummins ISL in Monaco Dynasty

[zmotorsports]

I have been wanting to install a FASS fuel pump on the Cummins ISL in our 2003 Monaco Dynasty for quite a while now and finally was able to complete the installation.

I know there have been a lot of installations over the past few years of either the FASS or the AirDog fuel pumps. I documented the complete installation over on my Mods/Repairs thread for our coach but I thought maybe I would post it up here on the Cummins sub-forum as well as maybe it will help someone with their installation that may not follow along on my coach thread.

I hope this is helpful to anyone wanting to install a FASS fuel pump in a Monaco coach on the Roadmaster S-Series chassis.

Follow along as I try to document the installation of a FASS fuel pump into our 40' Monaco coach. Prior to beginning I wanted to get some jackstands under the coach and create a bit more space to crawl around.


Here is the system I went with. The FASS Titanium TS-D08-165G. Also some assorted NPT to JIC adapters & fittings.






Mounting the pump and filter assembly was the first item to address as space above the fuel tank was not adequate. The surge tank for our Aqua-Hot system also resided right behind the passenger steer tire in the fuel tank bay so after much deliberating I opted to relocate the Aqua-Hot surge tank and mount my FASS assembly in its place.
Aqua-Hot surge tank removed.


Area sanded with a DA and repainted with some extreme duty satin black paint.


Aqua-Hot surge tank relocated nearer to the Aqua-Hot unit after moving the primary and secondary water filters inboard about 2 inches. FYI, this is where the surge tank is mounted on the Executive and Signature models but their storage bags are slightly larger than on the Dynasty model.


Stay tuned for much more of the installation....

[zmotorsports]

Next was to design and build the mounting bracketry for the FASS pump and filter assembly. I don’t want to merely bolt to the approx. 12-gage steel sheeting at the front of the fuel tank bay. Partially because of support but also I didn’t want to create a “tinny” sound from the pump being mounted to thin sheet metal.

I decided to build a brace spanning across from the main chassis rail to the outer structural support then just tie into the sheet metal for extra support.

I found a scrap piece of 1.250” x .188” wall square tubing that was about the perfect length.


I don’t like bolting through square tubing without spacers to prevent crushing. In this relatively thick walled tubing I could have been fine but overkill seems to be my theme on projects.






Next was to weld the ends that would tie into the chassis rail and outer structure.




Test fit to mark pump placement on the bracket.


Machined a couple of threaded bosses for the pump mount.






Mounting bracket nearly completed and prepped for paint.






Corresponding mounting plate being drilled with the same bolt pattern where a rubber isolator will be sandwiched between the pump and mounting bracket.


Painted and ready for final installation.


Bracket installed.


More to follow.....

[zmotorsports]

Prepping the pump by installing fittings.

1/2” NPT to a -10 JIC elbow. This will be the supply from the tank.


1/2” NPT to -10 JIC straight (black fitting) for the pressurized and filtered fuel leaving the pump manifold. The silver fitting is a 1/2” NPT to a -8 JIC which is the FASS return to the tank. This will run to a bung in the opposite side of the tank.


Pump and manifold assembly fastened to the mounting bracket.




This “T” will be where the return line connects.


I opted to cover the return line with some abrasion covering to provide a bit more protection to the hose as well as to hide the bright blue hose and make it appear more OE looking. The best mods are hidden in plain sight.


Return line completed.


Return line installed and connected at the driver’s side of the tank and to the FASS manifold assembly.


I had a couple of new 5/8” fuel lines made up with -10 female JIC connectors crimped on at my local hose supply house. One hose was 32” in length and went from the FASS outlet to the original hose feeding back to the rear of the coach. I remove the original hose from the tank and joined them with a -10 JIC male to male union. I then connected the 40” hose from the tank port to the inlet side of the FASS manifold.


Hoses done and filters installed. These will be easily accessed for filter servicing.


More to follow.....

[zmotorsports]

Moving to the rear engine bay.

Seeing as how access to my original secondary filter was limited, I opted to remove my primary filter and relocate my old secondary filter to its location. This will provide a third filter in the fuel system and just before the CAPS pump. Probably overkill.

This is also where I deviated from most other people’s installation. I identified the hose on the right in the photo as the original feed from the tank. This is now the supply hose from the FASS pump assembly.

The hose on the left in the photo used to go from the primary filter to the OEM lift pump. I chose to remove the hose at the lift pump and connect it directly to the CAPS pump inlet. This allowed me to remove the other hoses completely from the coach and thus bypassing the OEM lift pump.


Original secondary filter head and mount which will be mounted under the left rear run box in place of the primary filter.


The filter head has a metric plug at the top. I purchased a 10mm x 1.0 to 1/8” NPT adapter and a 1/8” NPT “T” fitting.




Filter head installed. This will be filter #3 in the system. I also installed a liquid filled 1.5” diameter fuel pressure gauge and a sending unit that will support a cockpit mounted fuel pressure gauge. This pressure will represent what is being seen at the CAPS pump and provide me with data to know what my pressure is at load as well as monitor when my filters will be in need of servicing.


Hoses connected.


Filter installed.


WIF (Water In Fuel) sensor wire extended, covered in convoluted casing to match OEM wiring and connected to the sensor at the bottom of the filter.


More to follow......

[zmotorsports]

Next was to bypass the OEM lift pump.

I removed the hoses and capped off the inlet and outlet of the LPM (Lift Pump Manifold) then extended the wiring for the lift pump. The inlet hose going to the OEM lift pump now goes directly to the CAPS inlet. This portion of the entire project was hands down the most difficult part because of how limited the access is to the OEM lift pump.




To fool the ECM into thinking the OEM lift pump is still connected a small load must be placed on the circuit. Many are just using an auxiliary relay such as for lighting and putting female connectors on the wires and connecting the relay then zip-tying the relay to the wiring harness near the OEM lift pump. This works perfectly but in the event that the relay ever fails it will require squeezing back into the area where the OEM lift pump resides and not easily accessed on our coach. I chose to extend the wiring in abrasion covering back to the right rear run panel and place the labeled relay inside of the enclosure.

I also prefer to use OE style connectors when possible so I spent a few bucks more and purchased a relay and wiring harness as an assembly. This is the NAPA relay made by Echlin that I used.


Seeing as how there is no load on the relay and I only needed the control side I removed the non needed wires altogether. I kept the wires going to pins 85 and 86 which are the coil in the relay.




Labeled the relay.


Mounted the relay.




Reinstalled the cover back on the right rear run box.


That is as far as I’ve made it so far. All that is left is the wiring to the FASS pump and she’s ready to fire.

Thanks for looking.

[zmotorsports]

While I was at it I opted to install a pyrometer and fuel pressure gauge feeding to the cockpit.

Drilled & tapped the exhaust manifold to accept the K-style pyrometer probe.


Secured wiring away from the exhaust heat.


Ran the wiring for the fuel pressure sending unit into the left rear run panel and tie into the wiring in which I run through the chassis and up to the cockpit. Encased it in abrasion coating to appear OE.




Machine a couple of aluminum standoffs to mount the pyrometer extension module.


Extension module mounted and wires connected.


Labeled.


Left rear run box buttoned up and everything at the rear is now completed.


Thanks for looking.

[zmotorsports]

Last part of the installation.

I ran the wiring into the front run box which is on the driver’s side just ahead of the steer axle.

I used the wiring harness that came with the FASS fuel pump and installed the relay on the side of the run box and tapped into an unused “key on” power terminal with a 3 amp fuse.




Battery feed side of the relay tapped off power feeding the run box fuse panels through a 10 amp fuse and everything labeled.


After double checking the wiring and connections at the run box and at the pump I loosened the secondary filter/water separator at the FASS pump and prepared for priming.

Turned the key on and as soon as the pump tone changed I hurried and tightened the secondary filter. Only had a very small amount seep out before I was able to get it tight.

I could hear bubbles and air being being forced out through the return line and into the fuel tank but the entire system was drained so I figured it would take a minute or so, plus this gave me a chance to check all hose connections as well.

After cycling the key again I cranked it and she fired right up. It stumbled ever so slightly as there was air between the third filter and the CAPS injection pump that had to forced through and returned to the tank but it smoothed right out and idled great.

I let it run for several minutes before shutting down and letting it sit while I swept up and put tools away.

After about fifteen minutes I restarted and it fired right about like it always has but I noticed right away it idled smoother. I just thought maybe it was the placebo affect but my son stopped by and I asked him what he thought. His first comment was “it’s idling smoother”. I then figured maybe it actually is and not just in my head.

All in all a great modification and after a few more items on my gauge panel and wiring I can take her out for a spin.

Thanks for looking.

[zmotorsports]

Lastly, here is the video of the installation of the FASS fuel pump on our coach.

https://www.youtube.com/watch?v=GVszhK4JFcg

[Alpine36]

Very nice work, great write up.
Makes my install look rather amateur lol...
I also left the "third" fuel filter in the engine bay. What the hell, why not?
You'll love this upgrade. Ours runs better than ever.

[zmotorsports]

Originally Posted by Alpine36

Very nice work, great write up.
Makes my install look rather amateur lol...
You'll love this upgrade.

Thank you.

I checked out your installation and was quite impressed. Very nice work.

[Alpine36]

Originally Posted by zmotorsports

Thank you.

I checked out your installation and was quite impressed. Very nice work.

Thanks. I've managed to put about 4K mi on it since the install.
Funny you mentioned a smoother idle, so did I. Can't say fuel mileage has changed, but I have noticed a slight gain in torque at 1,750 rpm (our ISCs sweet spot) pulling Snoqualmie pass pulling the TJ. The converter stays locked up longer and far less downshifting.
From one old wrench named Mike to another...cheers and safe travels.

[TR4]

Great write up! Thanks for sharing.

Bill

[zmotorsports]

Originally Posted by Alpine36

Thanks. I've managed to put about 4K mi on it since the install.
Funny you mentioned a smoother idle, so did I. Can't say fuel mileage has changed, but I have noticed a slight gain in torque at 1,750 rpm (our ISCs sweet spot) pulling Snoqualmie pass pulling the TJ. The converter stays locked up longer and far less downshifting.
From one old wrench named Mike to another...cheers and safe travels.

Awesome. Snoqualmie Pass is gorgeous and 1750~ish is about the sweet spot for cruising with my ISL as well. Setting the cruise at around 1750 nets me approximately 66-67 MPH which is where everything seems the happiest and where it usually sits. I’m excited to get some mikes on her after one more project.

[zmotorsports]

Originally Posted by TR4

Great write up! Thanks for sharing.

Bill

Thank you. I appreciate that.