Beefcake

Ok so i got the Fass 150 installed on my truck a few days ago and an autometer FP gauge. Sometimes the gauge holds steady at 16psi but sometimes its bouncing from 14-17psi and when it does you can here the pump whine (like its surging). Truck is running fine though. The new drawstraw was installed in the fuel tank and the fuel tank was cleaned out before it was re-mounted. The fuel pressure gauge looks to be somehow tapped into the top of the FASS system, which is mounted behind the fuel tank because other areas were being taken up by other stuff. I cant see exactly where the gauge is plumbed into though as I would have to drop the spare tire and with a -40 winchill its not happenin right now cause im on the road working. It seemed like the colder it got out the more the pump is whining. Im running a decent anti-gel though so I dont think its fuel gelling. Is this whining normal? Or what is it doing? I read the FASS troubleshooting manual but its not a huge help at this point until i get it back home in my garage. I would have done this myself as all of the work has been done by me and a friend in my garage with no problems but the truck broke down on the road so i had no choice to take it to a shop and i didnt want anymore stock lift pump problems and I plan on putting more power into it so I opted for this system. Anything to check for or suggestions, I dont know enough about it yet as I didnt install it. Thanks.

UPDATE:

So I notice the (whiney surging noise) is something to do with the fuel returning from the CP3 through the return line and going back into the tank. I took the cap off the fuel tank and could here the fuel splashing back into the tank, funny enough the fuel returning to my fuel tank is in sync with my gauge bouncing around as if they plumbed my sending unit into the return line??? Just guessing but thats all i could come up with. Another thing i noticed was when i take the fuel cap off the tank is under a vacuum after awhile. Shouldnt the tank have a vent line? The mechanics shop said they plugged up a few lines that werent supposed to be open?? Im phoneing the shop in the morning and gonna get this figured out cause after that hefty bill they can fix it for free.

sallyman1

where did u get it done? in saskatchewan?

sallyman1

reason is im getting a fass 150 installed and i told them to add lines to the vents to keep debris out. hope they do it right? where did they mount yours? did they bypass the stock fuel canister?

Beefcake

No it was done in Medicine Hat, Alberta, and its going back in tomorrow so they can look at it cause i shouldnt be having these problems with a new system. No they didnt bypass the stock canister but thats fine I didnt want them to. Reason being is my old lift pump is still in the tank (draw straw was installed so old pump isnt being pulled through) and works but is not the greatest, but if the FASS ever died all I have to do is plug the stock pump back in and away I go, seeing as how i put on lots of km in the oilpatch, some being in remote locations, any backup is a good backup. My FASS is mounted over the rear axle because the usual spot they like to run it on the frame rail is being taken up by the flex pipe for my Fatboys nerf bars with the buillt in side piped exhaust, I also have a 3" body lift on my truck which makes it able to have to pump there with the clearance, a stock truck I dont think would, it would be too close to the axle.

jhenson

I've had the same problem with my AD150 for several months now but I don't think the cold has anything to do with it. You are right about the fuel return being in sync with the noise because there is a ball and spring that regulates the pressure on the return line port from the pump housing. Mine has the same pressure jumps as you are seeing. I'm almost starting to wonder if the fuel treatment has something to do with it (i.e. eroding the plastic ball or something of that nature). The ball pushes against the spring and opens the line to return fuel. I also wonder if the spring could be weakening? Keep us posted on what you find as there are numerous posts on this issue.

sallyman1

okay so im trying to figure this out. they didnt bypass your stock filter housing so does your fass run through it as well? or just your fass, and goes str8 to cp3?or does it go fass right to stock canister? if so how can u just plug your old pump back in?The fass shouldnt really fail should it? it has a 6yr warranty.

homewrecker

The colder it is the louder the whining or at least thats how my Fass does.The cycling is normal,just the return flow to the fill neck.I ran an Autometer fuel gauge at one time and it had its moments just like you have mentioned.I didn't know if it was messed up or if it was just sensitive to the way a Fass regulated pressure.I ended up switching to a DiPricol gauge and it sits steady on 20lbs at idle.I'm curious as to why they ran it through the stock filter.If you are running a 2micron on the pump then I don't see the need to run it through the stocker.Also the Fass will pass fuel even if it fails.I have drove several miles with the harness unplugged(on accident)and had no problems at all.Couldn't even tell it wasn't running if it wasn't for the gauge reading zero.Cp-3's were designed to be able to pull their own fuel.

sallyman1

yes thats true. apparently some duramaxes never used lift pumps on their cp3s. would not running the fass through the stock fuel canister effect cold starting? because we will no longer be using the fuel heater?

homewrecker

Lots of guys north of the border have commented on having no problems not using the fuel heater.The Fass has ports to run coolant lines to heat the fuel but I have never read of anyone actually using them

Mighty Goat

what a stinker. All that money for something, you'd think they would have refined the FASS a little by now.

sallyman1

if the fass fails can you just put power to your intank pump and be off again? i doubt it because if our stock canister is bypassed we would need to hook that up again as well and bleed the system again?or am i wrong? because the place thats installing mine says they are bypassing my stock canister all together

homewrecker

I left everything stock inplace.The stock fuel line to the cp-3 is sealed up with a bag and I keep the banjo bolt and pump relay in my spare parts kit in the truck.If I had to switch back its as simple as removing the Fass line and fitting from the cp-3 and putting the banjo bolt back through the stock line and reinstall the lift pump relay.Completely stock again.

sallyman1

are both pigtails the same or would you have to rig it up so they are?

Diesel-Dan

Well the cooler the fuel is, the thicker it is. Then you will also note the pump being louder due to this added strain of moving the fuel. Also with the fuel thicker, it will hold more air. SO when you put it under a vacuum, the bubbles will enlarge and collect in the water separator. Once the air being built up has overcome the filter nipple, it will be drawn into the pump in a big chunk. This is the stuttering you are possibly hearing.

Depending on your gauge, it might reflect this as a slight loss of pressure due to the air is…well not fuel. SO a momentary blip is noted on the gauge. Usually electric gauges are notorious for this as they are quite sensitive. This is especially true if your graduation on the gauge is on the smaller side. This noise is considered to be normal operation and will be more noticeable when the weather is colder.

The gauge is more than likely attached on our “G” port which is post filter on the pressure manifold. The return fuel from the FASS is more or less unused aerated fuel form the engine being sent back to the tank. The CP3 return should be separate from this.

If they plugged your vents on your tank, this will eventually cause issue, and also limit you on how fast you can add fuel to your tank. Not to mention how much fuel. You will need to address this with the shop if they did plug the vents. I can see the FASS create a vacuum in the tank as its pulling out more fuel than its returning. More or less the exact amount that the engine is using to run. SO if the vents are not allowing the vacuum to bleed….it will build up over time.

You also might "once over" the install and pay close attention to the suction line since this was a custom install. Make sure there is no tight bends or kinks that might be adding to the noise.

Thanks for adding some constructive comments to aid in this gentleman finding a resolution to the things he is seeing.

coolslice

Maybe I'm not understanding what you've described, but my FASS will do that when the grid heater is cycling. It will usually do it when it first starts, usually when it's cold. I just assume that it is drawing power to run the grid heater, and you can hear the change in current in the pump.