FASS Fuel System Install

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FASS Fuel System Install

March 22, 2024, 10:46:34 pm

Last December, I had to have the CAPS fuel pump on my 2004 U270 replaced. Here is the link to the thread covering my fuel pump failure and replacement:
Won't start after changing fuel filters

For anyone who has the CAPs fuel pump, know that if it fails you are looking at a repair that can run in excess of $10K. As others have stated on the forum, problems with the fuel delivery system to the CAPS pump likely contribute to the issue. Others believe the main issue is air entering the system, likely through the lift pump. I believe it is more likely fuel starvation, which can be caused by a number of factors (lift pump issues, fuel line issues, clogged lines and filters). Either way, the FASS system is a good solution because it delivers a constant supply of fuel under low pressure instead of relying on the CAPS pump to suck fuel through 20-25 feet of fuel line.

I decided to do the FASS update and bought the pump in December, but I had been carrying it around until last week, waiting for a good opportunity to install it. Last week the coach's Engine Maintenance light, and then Stop Engine light, began coming on, after which the coach would die. Because of the previous problem, I immediately suspected the fuel system and decided to do the FASS install, even though I was not at a location ideally suited to such an install (I was at a relative's place outside of a tiny town in Mississippi). Ultimately, I found (after installing the FASS system and finding it did not fix the problem) that the problem was a bad coolant level sensor (don't buy a cheap one from Amazon). Still, I am glad to have the install and would like to share a few notes for the benefit of owners with a similar coach.

The installation was easy overall. FASS recommended the Industrial Series 165 GPH system for my coach. The Industrial Series does not require a new fuel return line; the fuel return can be tied into the existing return line. I spoke with two FASS representatives who confirmed that there is no problem using the existing line with this system. One problem, however, is that the fuel return line on the ISL is routed using steel lines back through the housing of the lift pump. To remove the lift pump would require some very involved re-plumbing of the lines, which I couldn't do where I was working on the pump. Instead, I chose to leave the lift pump in place and tie into the return line as it exits the lift pump housing, using the adapter provided with the FASS system. I installed a relay connected to the wires that used to go to the lift pump so the ECM would think there is a load.

The main problem with the install on my coach was the space to install the FASS. I installed the FASS in the same location as the old primary filter so that I wouldn't have to reroute and extend the fuel lines. The problem is that the FASS pump barely fits in the space, right between the air dryer and the ride height valve. As the pictures show, there is only about I/8 to 3/16'' between the FASS filter and one of the air dryer lines, and there is only a little more clearance between the input line fitting and the ride height rod. It might be possible to get more clearance on the input side by moving the FASS assembly lower, but that would cause other clearance issues on the output side. The mounting I did, while very tight, appeared to be the best option on this coach.

Everything else was simple. I wired the power lines directly to the batteries in the same compartment and the control line to a switched fuse on the inside of the bed compartment. With a good place to work and all supplies on hand, the entire installation on my coach could be done in 4-6 hours. It took me probably twice that because of where I did the job, but I am glad to have it done.

Re: FASS Fuel System Install

Reply #1 – March 23, 2024, 01:00:22 am

I really think it a great addition to a caps system. I eventually will have one on my 320. I carry a spare coolant level switch and several other sensors that will strand you. Cheap insurance IMO

Re: FASS Fuel System Install

Reply #2 – March 24, 2024, 09:04:41 am

dbeenett9, I love the idea of the FASS system but what has been holding me back from the install is a FASS rep. said the pump was not designed to pull fuel from the tank that far. What has been your experience with the pump as far as self priming and have you pulled the fuel tank level down say below half a tank. I have installed the FASS system on hi HP Cummins 5.9 and 6.7 engines but the pump was with in 3-5 ft. of the tank. Any thoughts? Thanks for the info. Mike

Re: FASS Fuel System Install

Reply #3 – March 24, 2024, 11:13:56 pm

Quote from: zmpm01 – March 24, 2024, 09:04:41 am

dbeenett9, I love the idea of the FASS system but what has been holding me back from the install is a FASS rep. said the pump was not designed to pull fuel from the tank that far. What has been your experience with the pump as far as self priming and have you pulled the fuel tank level down say below half a tank. I have installed the FASS system on hi HP Cummins 5.9 and 6.7 engines but the pump was with in 3-5 ft. of the tank. Any thoughts? Thanks for the info. Mike

I have had the full Fass titanium system on our 2001 U295 for about 2 years now. MY Fass rep (Gene) stated just the opposite as for distance, no problem at all. Several of the FASS install videos on youtube and similar show the pump system being mounted at the very rear of the coach. Primes very easily even after filter changes. I rarely go much less than about 3/8 tank, but never any issues. I installed my system above/behind the cranking batteries in place of the old primary fuel filter....here is the link to my full install.

FASS fuel system install upgrade

Re: FASS Fuel System Install

Reply #4 – March 24, 2024, 11:47:52 pm

I mounted mine the same place Mike did and I have gone down to a quarter of a tank of fuel
with no problem. I have the old system that needed it's own return line so I welded a 3/8th
piece of plate to the top of the tank to return the fuel back to the top of the tank.

Re: FASS Fuel System Install

Reply #5 – March 25, 2024, 10:56:11 pm

Thanks for the information, Now I have another project to add to the list!

Re: FASS Fuel System Install

Reply #6 – March 28, 2024, 09:26:14 pm

Like the others, I mounted the FASS system in place of the old primary filter, above the batteries. When I installed it, only about 1/4 to 3/8 showed on the fuel gauge. The pump primed very easily; I ran the pump for about 30 seconds with the key on, then started the coach. It died after a few seconds, then started up again immediately and that was it. The FASS representative I spoke to also did not indicate that the distance from the tank is an issue. So far (300-400 miles) I have encountered no issues. One thing I do plan to do is add a fuel pressure gauge, so I can always be sure there is a good supply of fuel at the right pressure since fuel supply issues seem to be at the core of CAPS failures.

Re: FASS Fuel System Install

Reply #7 – March 29, 2024, 02:59:52 pm

Same here, added shutoff ball valve before the pump and one after the old primary filter to minimize issues when changing filters, also have dash pressure gauge plus one on the pump,

Re: FASS Fuel System Install

Reply #8 – March 29, 2024, 03:36:02 pm

Curious if anyone has given consideration to the FASS optional fuel heater system?

https://fassride.com/wp-content/uploads/HK-1002.pdf

Re: FASS Fuel System Install

Reply #9 – March 29, 2024, 07:30:32 pm

One Q. Is the FASS system supplementary to the CAPS pump or can it substitute for CAPS if it fails?

Re: FASS Fuel System Install

Reply #10 – March 29, 2024, 11:42:33 pm

It is simply a transfer pump for the CAPS injector pump system, to insure sufficient fuel delivery to the injector pump.

Re: FASS Fuel System Install

Reply #11 – March 30, 2024, 12:03:11 am

Yes but also in addition to a lift pump and supplying positive pressure to the CAPs pump it also removes all the micro air bubbles from the fuel and scrubs fuel and returns it back to the fuel tank. By eliminating the air higher fuel pressures are achieved and more efficient operation. Also with the air removed fuel nozzles dont hammer when closing do to the fuel not compressing increase their life span, or at least this is part of their sales pitch. I do agree with the higher fuel pressure from the fuel injection pump. My ISB truck with the aux filter comes with the heater, but ive never hooked up for southern nevada.

Re: FASS Fuel System Install

Reply #12 – March 30, 2024, 12:35:38 am

I am going to check out about the fuel heater as I have never heard about them before but it may
make for easier starting in the cold. My coach starts up fine down to 14 F without heating the engine
but with heated fuel maybe it will start at 0.

Re: FASS Fuel System Install

Reply #13 – March 30, 2024, 11:27:36 pm

Didn't consider the heater. I just try to avoid any temperatures where I might need it.

Re: FASS Fuel System Install

Reply #14 – March 31, 2024, 12:12:02 pm

Quote from: Chuck Pearson – March 29, 2024, 07:30:32 pm

One Q. Is the FASS system supplementary to the CAPS pump or can it substitute for CAPS if it fails?

It replaces the small electric Lift pump, but also as others have stated, keeps positive pressure to the CAPS pump AND removes all air from the fuel prior to that.......the CAPS pump is what increases the pressure for the fuel rail/Injectors.
One of the common well documented reasons for CAPS pump failure is, Too much air in the incoming fuel from a failing lift pump gasket or cracks in fuel lines. The air causes the CAPS pump to lose lubricity as well as overheat and causes mechanical internal damage.

Re: FASS Fuel System Install

Reply #15 – March 31, 2024, 06:46:52 pm

Quote from: mkc1962 – March 31, 2024, 12:12:02 pm

It replaces the small electric Lift pump, but also as others have stated, keeps positive pressure to the CAPS pump AND removes all air from the fuel prior to that.......the CAPS pump is what increases the pressure for the fuel rail/Injectors.
One of the common well documented reasons for CAPS pump failure is, Too much air in the incoming fuel from a failing lift pump gasket or cracks in fuel lines. The air causes the CAPS pump to lose lubricity as well as overheat and causes mechanical internal damage.

So, much like the VP40 injection pump on 24 valve Cummins that fails quickly if the $15.00 Carter lift pump fails? I thought the CAPS had a low pressure pump module in it. No experience with it, hence the uninformed questions.

Re: FASS Fuel System Install

Reply #16 – April 01, 2024, 01:39:28 pm

UP95G - Heavy Duty Lift Pump for Cummins ISC & ISL CAPS Fuel System

I suppose you could keep your existing filter setup and install just a fass pump.

Mark

Re: FASS Fuel System Install

Reply #17 – April 01, 2024, 10:58:14 pm

Quote from: MAZ – April 01, 2024, 01:39:28 pm

UP95G - Heavy Duty Lift Pump for Cummins ISC & ISL CAPS Fuel System

I suppose you could keep your existing filter setup and install just a fass pump.

Mark

You can....but you wont get all the mounting hardware and added benefits of the constant fuel scrubbing and air removal of the complete system for not much more $ .

Re: FASS Fuel System Install

Reply #18 – April 01, 2024, 11:05:32 pm

Quote from: Chuck Pearson – March 31, 2024, 06:46:52 pm

So, much like the VP40 injection pump on 24 valve Cummins that fails quickly if the $15.00 Carter lift pump fails? I thought the CAPS had a low pressure pump module in it. No experience with it, hence the uninformed questions.

The CAPS injection pump itself IS what sucks the fuel after the lift pump primes/starts the process. But that function in itself is part of the problem. Its not a very robust setup and any failure such as air leaking on the suction line causes internal heat and possible mechanical damage to the pump or other parts of the injection pump. To quote several Cummins techs I spoke to years ago...." CAPS was not a very proud moment for Cummins, but its failures do make service centers a lot of money"...Keeping constant incoming fuel flow/pressure into the CAPS pump is the best that anyone can do to ensure it lasts a long time.

Re: FASS Fuel System Install

Reply #19 – May 28, 2024, 05:21:28 pm

I don't see the need to start a new thread, and not much details to share as this was a very straight forward install, but I successfully installed the 165gph FASS Industrial setup into my 2000 U320 over the weekend. I'd say it took me about 12 hrs total. For my coach, I did not need any additional fittings, I was able to complete the installation with everything supplied in the kit. I removed my engine battery tray frame and welded in a couple of cross members to mount the FASS unit to. The frame rail is far too close to the floor to be able to mount the FASS directly to the frame. I re-routed my fuel lines, and will monitor them closely as the supply hose has a bit tighter radius that I would prefer, but certainly isn't kinked or close to kinking. Return hose goes to the engine return line and the return fuel goes through the fuel cooler before returning to the tank with the rest of the unused fuel from the injector pump.

The reason for my upgrade was that I was fed up with losing prime on my Racor system. The 300200 filter housings would warp and leak, and the engine would sometime stumble at idle due to the leaky unit. I have gone through four of the 300200 filter housings in about 15000 miles. I am hoping for better fuel economy (I dont track it so I wont ever really know), and also more power for the hills. I have a brand new 300200 filter housing and the racor unit/controller I will be putting in classifieds when I return from vacation.

Before:

After:

I utilized the old mounting holes in the frame to secure the relay and the fuse holder. The supplied harness from FASS is very long, I trimmed about 4' or so out of the trigger wire and power/ground leads. Overall, I think the cost difference between the FASS and other options out there to replace the old Racor system are worth it for the FASS. I think it was $300 or so more than other options I was looking at, and picked up the FASS on a 10% off sale directly from their website during black friday last year.

Wave or honk if you see me on I-15 over the next couple weeks coming or going. We're headed to St. Anthony ID for some sand therapy since our normal playground in Glamis is too hot this time of year.

Re: FASS Fuel System Install

Reply #20 – May 28, 2024, 07:16:45 pm

Did you use the return fitting or add an additional return to the tank? I think the idea of having a on board fuel polishing system is great. Removing all the air is not talked about much but is a big deal when you look at injection final pressures. Please post back if you notice improved economy or being a little more peppy. Wish I had mine done!!! Does your have a fuel cooler?

Re: FASS Fuel System Install

Reply #21 – May 28, 2024, 07:36:30 pm

I put the Fass system in too and the Racor system doesn't take the air out of the fuel. When I got mine
I had to run a separate fuel line. Nice job.

Re: FASS Fuel System Install

Reply #22 – May 28, 2024, 07:45:04 pm

Quote from: dsd – May 28, 2024, 07:16:45 pm

Did you use the return fitting or add an additional return to the tank? I think the idea of having a on board fuel polishing system is great. Removing all the air is not talked about much but is a big deal when you look at injection final pressures. Please post back if you notice improved economy or being a little more peppy. Wish I had mine done!!! Does your have a fuel cooler?

I used the return fitting included from FASS and put it right at the return from the injection pump at the engine. This return from the injection pump goes to the fuel cooler and then back to the tank. I'll snap a photo tonight. I considered putting the FASS return downstream of the fuel cooler, which would require me to procure a couple additional fittings, but I don't think I'll have any issues with the install considering this is what FASS recommends (tie into existing return VS. running a dedicated return).

Unfortunately I don't track fuel mileage, mostly because the "fill level" is never an exact repeatable point. The second reason is if I cared about fuel mileage, I wouldn't be doing this to begin with. We drive at 65-70mph once we get into the free states of America, and you just cannot care about mileage when youre pushing a brick at 70mph with 10k in tow.... IME, calcuated mileage will vary based on how full the tank gets, which is not repeatable with our filler neck/tank systems. I have seen where some Silverleaf systems will report burned fuel, but I can't say I would trust that number to give accuarate data, it has to be an estimate as there isn't a calibrated flow meter from the injection pump to injectors.

I can't imagine I WONT feel a difference in power, my old system had to be sucking air based on how quickly it would lose prime. For reference, when I removed the old system coach had been off for less than 12 hrs, and i lost probably less than 1/2 cup of diesel from the disconnected lines. I was setup with diapers and a catch/drip pan expecting a lot more than what I encountered.

I have a trip to Idaho & back, leaving Thursday. I've made the trip 3 times in the past, and there are a few long grades that I recall having to shift into 3rd and sit at 45 mph and climb up. If I'm able to pull them at a higher speed, it'll indicate more HP being produced. I don't have Silverleaf or any add-on monitoring, just the factory gauges, so I won't have any data other than my SOTP dyno.

Re: FASS Fuel System Install

Reply #23 – May 28, 2024, 11:18:26 pm

Return line final arrangement. -04 300psi rated hose from FASS kit, along with the -08 black aluminum Tee.

Re: FASS Fuel System Install

Reply #24 – May 29, 2024, 10:01:23 am

So I too think running the return through the ECM fuel cooler will add additional cooling for the ECM. When I asked about the fuel cooler I was asking about a fuel cooler outside of your CAC. You can look through the outer louvers and see if you have one installed. The ECMs need all the cooling they can get and running at higher power settings, hotter outside temperatures and less total fuel in the tank will see higher ECM operating temperature. You will see the fuel tank temperature rise quite high. There was a changeover when they started adding the fuel cooler and I think your build was near that time. If you dont have one, I would add one on my coach. ECM failure is not fun at all.

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