Fass on an OBS!?

Has anyone installed a FASS HD system on an OBS truck before? I know the kit is made for the 99-03 but I had a buddy buy one of these and i got to do the install.

We used an Irate Diesel Regulated Return and fuel bowl delete, then used the FASS for filtration and pump.

I finished it all up today, leak free, starts and runs good. I just have a couple questions because ive never worked with a FASS before.


1) Why in the hell is this thing so loud, you can hear it when the truck is idling!

2) Is it okay to cap off the ports used to return fuel to the tank and just have a "IN" and "OUT" on the FASS? I say this because we just used the factory return from the regulator up on the motor.
Seems to be working alright, its just very very loud and almost hurts to have it running because i feel like it wants to grenade.

I believe the FASS is enough like the AirDog to give input....

The return is required to be open and sent to the tank because that is how it rids the system of air. That may be why it is so loud.

If you got the stock fuel pump, kinda pointless.

PsRumors said:

I believe the FASS is enough like the AirDog to give input....

The return is required to be open and sent to the tank because that is how it rids the system of air. That may be why it is so loud.

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Alright that makes sense, i took the cap off the side when it would connect to the tank, there is a check ball in there and that check ball opens only when the pump senses 55psi and it then sends the excess fuel and air back to the tank. I have my regulator up on the engine set at 50 so that check ball/valve is never going to open, i can run the return uncapped and it doesnt pour any fuel out.

Is there a way to use this as a standard pump like a walbro or stock SD pump?? I dont want it to send anything to the tank and i dont even care about air removal, i just want it to filter and pump fuel. Seems like its doing its job, its just doing it a little more noisy than id like. Others have complained about the larger FASS systems being loud, I just didnt expect this loud!

Magnum PD said:

If you got the stock fuel pump, kinda pointless.

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Stock fuel pump is deleted also. This is the only pump, it sends fuel to the back of each head and is returned to the tank via a regulator and new fuel line back to the selector valve, then it goes from there into which ever tank you have selected

I'm interested how this all ends up working for you, cuz I need to work on a e-fuel set-up of some sort after i get my turbo situation figured out.

The general consensus seems to be that you need to feed the injectors with about 60 psi.

I hope you have good luck with that pump. All the ones I have been around were pretty loud.

Yeah its definitely loud, but he is driving the truck. Its set at 55psi, thats all it will put out without premature pump failure they say.

With stock injectors im not worried about it, we will play with the pressure issue later on if he goes bigger

So far so good bro! Besides being loud, my throttle response is ALOT better. And even though Im still mostly stock, seems like Ive got a little more ummmmppphhh. Im happy. Thanks for your help! Next on the list........T500 hpop

Few fun facts....

You can run the FASS pump clear up to 80 psi if you want. I ran mine at a constant 70psi and never had any bleed off issues like you speak of. Don't know where you got that info.

The pump return is a must. Just because the filler neck return supplied in the kit doesn't fit, does not mean you cant just tap into the factory fuel pickup assembly in the tank top for your return. Thats how I have done them. Used the factory pickup for a pump return and the factoy return port for the return of the regulator.

Since your using the draw straw (I assume) expect to have limited pump life. The FASS pumps are terrible at suck and blow. They live a happier life as a pusher pump off a sump

FASS issued a rubber dampening mat for the mounting plate to all those who had warranty pump work done. Was supposed to help with shock any vibration or things of that sort from the frame. It also helped quiet the pump down truemendously.

My truck ran better with the FASS pump then it has with the AirDog

I ate up 5 FASS motors before switching over to the AirDog. Warranty wss a royal pain after the second motor.

Throttle response is better because of how the fuel is now delievered to the heads in a constant state, rather then a pulse wave if you will. David Lott explained it to me many, many, years ago and it made perfect sense.

The AirDog is completely silent off my Hellmann sump. Sometimes I find myself checking fuel pressure gauges to make sure its still even running

Carry extra fuses and wiring with you on long road trips. The FASS pumps have been known to draw a load enough to melt fuse holders and wiring

Good luck

Powerstroked162 said:

Few fun facts....

You can run the FASS pump clear up to 80 psi if you want. I ran mine at a constant 70psi and never had any bleed off issues like you speak of. Don't know where you got that info.

The pump return is a must. Just because the filler neck return supplied in the kit doesn't fit, does not mean you cant just tap into the factory fuel pickup assembly in the tank top for your return. Thats how I have done them. Used the factory pickup for a pump return and the factoy return port for the return of the regulator.

Since your using the draw straw (I assume) expect to have limited pump life. The FASS pumps are terrible at suck and blow. They live a happier life as a pusher pump off a sump

FASS issued a rubber dampening mat for the mounting plate to all those who had warranty pump work done. Was supposed to help with shock any vibration or things of that sort from the frame. It also helped quiet the pump down truemendously.

My truck ran better with the FASS pump then it has with the AirDog

I ate up 5 FASS motors before switching over to the AirDog. Warranty wss a royal pain after the second motor.

Throttle response is better because of how the fuel is now delievered to the heads in a constant state, rather then a pulse wave if you will. David Lott explained it to me many, many, years ago and it made perfect sense.

The AirDog is completely silent off my Hellmann sump. Sometimes I find myself checking fuel pressure gauges to make sure its still even running

Carry extra fuses and wiring with you on long road trips. The FASS pumps have been known to draw a load enough to melt fuse holders and wiring

Good luck

Click to expand...

This is great to know. Thank you for the facts! The only reason I went with FASS was I found out they have the life time warranty that they never used to have. I got a great deal on it, and I was told the FASS works better on fords....? This is what I was told. So far so good but my dad used to run FASS in is 04 dodge and had nothing but problems with it, so he went to an Air Dog and has had no problems. So Im hoping I made a good decision . Also question about running the fuel up to 70 psi? FASS said to not run more than 55psi due to what the pump is factory set at. Right now Im running around 50psi, are you sure I can pump that up with my regulator? And what would the benifits be? Im pretty much stock right now but am in the process of building my motor to run 400 or so hp.
Thanks Powerstroked162

97pwrstroke said:

So far so good bro! Besides being loud, my throttle response is ALOT better. And even though Im still mostly stock, seems like Ive got a little more ummmmppphhh. Im happy. Thanks for your help! Next on the list........T500 hpop

Click to expand...

Yes we need to get a T500 for you very soon, Joey is pretty lazy these days so it might take him a couple weeks once you order it to knock it out LOLLOL

Powerstroked162 said:

Few fun facts....

You can run the FASS pump clear up to 80 psi if you want. I ran mine at a constant 70psi and never had any bleed off issues like you speak of. Don't know where you got that info.

The pump return is a must. Just because the filler neck return supplied in the kit doesn't fit, does not mean you cant just tap into the factory fuel pickup assembly in the tank top for your return. Thats how I have done them. Used the factory pickup for a pump return and the factoy return port for the return of the regulator.

Since your using the draw straw (I assume) expect to have limited pump life. The FASS pumps are terrible at suck and blow. They live a happier life as a pusher pump off a sump

FASS issued a rubber dampening mat for the mounting plate to all those who had warranty pump work done. Was supposed to help with shock any vibration or things of that sort from the frame. It also helped quiet the pump down truemendously.

My truck ran better with the FASS pump then it has with the AirDog

I ate up 5 FASS motors before switching over to the AirDog. Warranty wss a royal pain after the second motor.

Throttle response is better because of how the fuel is now delievered to the heads in a constant state, rather then a pulse wave if you will. David Lott explained it to me many, many, years ago and it made perfect sense.

The AirDog is completely silent off my Hellmann sump. Sometimes I find myself checking fuel pressure gauges to make sure its still even running

Carry extra fuses and wiring with you on long road trips. The FASS pumps have been known to draw a load enough to melt fuse holders and wiring

Good luck

Click to expand...

I did not use the return portion at all on his setup, its just capped off. And being capped off its working perfectly fine, the pump is just externally regualted rather than internally regulated. I am running it at 55psi just to meet the specs of FASS. Everyone on their side i talked to said to keep it at 55psi and you wont have pump failure, of course it will do more but then you decrease life as you just explained. I dont want to go through 5 pumps like you did, so ill keep it set where its at.

It is loud, thats about the only complaint. Everything else is working just fine! We will see how this thing does once the larger injectors go in

97pwrstroke said:

This is great to know. Thank you for the facts! The only reason I went with FASS was I found out they have the life time warranty that they never used to have. I got a great deal on it, and I was told the FASS works better on fords....? This is what I was told. So far so good but my dad used to run FASS in is 04 dodge and had nothing but problems with it, so he went to an Air Dog and has had no problems. So Im hoping I made a good decision . Also question about running the fuel up to 70 psi? FASS said to not run more than 55psi due to what the pump is factory set at. Right now Im running around 50psi, are you sure I can pump that up with my regulator? And what would the benifits be? Im pretty much stock right now but am in the process of building my motor to run 400 or so hp.
Thanks Powerstroked162

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Honestly going from 55 up to 70 you wont notice anything, as long as its holding a constant 55psi and never dropping you will be just fine. Although you said its at 50, you might as well go up to 55 just because they said thats allowed. I wouldnt go over that though if you want it to live, they were very high and mighty about leaving it there or you void the warranty.

Once we get some larger sticks in your truck that are rebuilt and idle very smooth we can play with the fuel pressure and find a happy spot, but for now 50-55 is just fine.

Now that your on the forums, start searching T500 threads because thats definitely the next thing to go on your truck haha. Also do a little poking around to find info on transmissions.... I know a lot of people who "can build a perfect transmission that will hold 500 no problem", then it fails and your up a stump. Just make sure you find someone you trust, not saying it HAS to be a BTS but you might give Brian @ BTS a call just to pick his brain about a local builder

You've already voided the warranty on his FASS pump if you have capped off the rerun line from the pump. I wish you had a clue how these things worked and why that is completely prohibitive of the pump doing it's sole purpose and intent.

The FASS is internally set at 55psi, sure. Your regulator will fine tune the pump from there. 55psi isn't much. I wish I could remember what stock was, but for the life of me I can't. I want to say 58psi sticks in my mind. I would turn the pump up, personally. That's based off my experience.

You are gonna have pump failures no matter what PSI you run it at. Nature of the beast. I know because I've tried it all, all different ways and it didn't matter in the end.

As well, I just lost my AirDog pump in the drag truck. Gave up the ghost after 4 years of 70psi. There's something to be said about that

Powerstroked162 said:

You've already voided the warranty on his FASS pump if you have capped off the rerun line from the pump. I wish you had a clue how these things worked and why that is completely prohibitive of the pump doing it's sole purpose and intent.

The FASS is internally set at 55psi, sure. Your regulator will fine tune the pump from there. 55psi isn't much. I wish I could remember what stock was, but for the life of me I can't. I want to say 58psi sticks in my mind. I would turn the pump up, personally. That's based off my experience.

You are gonna have pump failures no matter what PSI you run it at. Nature of the beast. I know because I've tried it all, all different ways and it didn't matter in the end.

As well, I just lost my AirDog pump in the drag truck. Gave up the ghost after 4 years of 70psi. There's something to be said about that

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Could you explain a little better, because when my buddy called fass for the return, they said to cap off the return line due to this system is for a 99 7.3 and newer. And I dont want to void my warranty! My truck is also a 97 not a 99 7.3 Just dont want to void my warranty, but ive been driving it for about a week now every other day or so and it seems to be running fine.

I have a very hard time believing that ANYBODY at FASS told him that LOL

The return off the FASS pump is there to return air and fuel to the tank. It's an Air Seperation System. Cap off the separator and all you have now is an overpriced fuel pump that's supposed to offer something it now can't. It may be running fine and your buddy might not think you need to worry about it but if that's the case you could have saved yourself a few hundred bucks and just bought an A1000 or two stock SD pumps.

There is no difference in the system for the SD to OBS trucks. Except that you can't use the filler neck return and you have to modify the mout plate a tad. You still run new lines from the pump forward on both trucks. Still song a regulated return on both trucks. You get the point.

I would set the pump up how it was designed to be used, that's just me

4yrs at 70 psi = respectable imo

Powerstroked162 said:

I have a very hard time believing that ANYBODY at FASS told him that LOL

The return off the FASS pump is there to return air and fuel to the tank. It's an Air Seperation System. Cap off the separator and all you have now is an overpriced fuel pump that's supposed to offer something it now can't. It may be running fine and your buddy might not think you need to worry about it but if that's the case you could have saved yourself a few hundred bucks and just bought an A1000 or two stock SD pumps.

There is no difference in the system for the SD to OBS trucks. Except that you can't use the filler neck return and you have to modify the mout plate a tad. You still run new lines from the pump forward on both trucks. Still song a regulated return on both trucks. You get the point.

I would set the pump up how it was designed to be used, that's just me

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Thanks! Appriciate the information!

Powerstroked162 said:

I have a very hard time believing that ANYBODY at FASS told him that LOL

The return off the FASS pump is there to return air and fuel to the tank. It's an Air Seperation System. Cap off the separator and all you have now is an overpriced fuel pump that's supposed to offer something it now can't. It may be running fine and your buddy might not think you need to worry about it but if that's the case you could have saved yourself a few hundred bucks and just bought an A1000 or two stock SD pumps.

There is no difference in the system for the SD to OBS trucks. Except that you can't use the filler neck return and you have to modify the mout plate a tad. You still run new lines from the pump forward on both trucks. Still song a regulated return on both trucks. You get the point.

I would set the pump up how it was designed to be used, that's just me

Click to expand...

I was told that by FASS and the company that sold us the FASS. Not saying the guy i talked to knew what he was saying, but i did in fact get told that. Basically they said "doing that will eliminate the air seperation feature, but should have no harmful side effects".
Sure eliminating air might be beneficial, but then again how many trucks dont have the air seperation part of it? Because of the intended use we just capped it off, later on down the road we could always hook it up. But for right now its capped and running flawlessly at 55psi.

Since you guys seem to have seen some success at 60+ with these FASS units i advised him to turn it up a little and see how he likes it, who knows the difference might be worth it

I was running my AirDog II @ 60 PSI and really like it, then I turned it to 65 PSI and WOW, what a difference. The throttle response is much much better at 65 PSI.