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So I have a basically stock 2012 Duramax LML 95K miles on it and decided to do a little fuel system upgrade. No I didn't do a ton of research on lift pumps, just enough to decide on a FASS system like any man would do. While internet shopping, I decided to go with the 165 vs. the 95. The install went well and I completed it placing the FASS under the fuel fill inlet.

I installed the unit according to directions and the job went smooth. :grin2: I bled system and fired up the truck. It had air sound going through the filters and thought, "Maybe I need to bleed it again?" So I repeated the bleeding several times. After this I was still having annoying (cavitation) noise coming from the filters. 'dunno;

I called FASS and talked with "Rick" he told me that the stock fuel sending unit was probably the issue. I watched several videos about the subject and decided to pull the sending unit and clean the screen. I found there was NO screen, just 2 - 3/8" holes in the bottom of the sending unit. I called FAAS and spoke to, you guessed it...Rick. He confirmed what I thought I might do. Drill about 4 - 1/2" holes in the bottom-side of the unit to let more fuel in. This did not work..same cavitation noise, but did improve power a little. The main difference is I went from 1/4 tank of fuel to FULL...all the time...:frown2:

QUESTION: Does anyone think there is any way that the 5/8" tank tube kit will fix this issue? I already have to drop a new fuel sending unit into the tank (I broke the float clips) the first time. The fuel pick up tube in the stock sending unit is only about 3/8" so I am wondering if the 5/8" tube is worth having to drill a hole in my fuel tank and if this might cure the cavitation.

Thanks
ChetMan
 

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Discussion Starter #2
Opinion on the 5/8" tube fixing FASS cavitation sound?

Any opinions on this cavitation would be appreciated. Thanks!

QUESTION: Does anyone think there is any way that the 5/8" tank tube kit will fix this issue?

I already have to drop a new fuel sending unit into the tank (I broke the float clips) the first time. The fuel pick up tube in the stock sending unit is only about 3/8" so I am wondering if the 5/8" tube is worth having to drill a hole in my fuel tank and if this might cure the cavitation.

Thanks
ChetMan
 

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Send everything back.... lick your wounds..... and buy a Kennedy like you should have from the beginning.
Never had a problem with my Kennedy. In fact Ive never even seen a post written with anything negative happening with them.
 
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Never had a problem with my Kennedy. In fact Ive never even seen a post written with anything negative happening with them.
Thank you for your input, however returning this product is no an option once it is installed.
 

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Thank you for your input, however returning this product is not an option once it is installed.
 

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Send everything back.... lick your wounds..... and buy a Kennedy like you should have from the beginning.
Thank you for your input, however returning this product is not an option once it is installed.
 

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Don’t buy the tank straw kit, It’s absolute garbage. Mine was throw down in the woods somewhere beside my shop. You can have it if you can find it. Buy a sump if anything, but I’d try what everyone else is saying and send it back. I bought the Fass straw kit, Fass pump and Fass fuel filter delete. The pump is the only thing that actually worked as it should. I’ll go another route for sure next time.


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I have the STK-1003 in my Dmax. Zero issues with it or the FASS.


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One word
BEAN...
 
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First the 150's - 165"s most people have this issue.
The reason these companies push the bigger pumps is so they can sell more parts which you would not need if you went with the FASS 95 and AirDog 100 both are good for up to 600 HP.
Another option would be to see if the 95 would fit in place of the 165, if so buy the 95 pump motor only and swap the motors out.
AirDog pulled that crap on me sending me a 4G165 under warranty replacing my FP-100, guaranteeing me I wouldn't have this problem.

I did, and when I called them a little upset, their brainstorm idea was installing a sump, just like all the other brainstorm ideas coming in.
I had a better idea, just sell me the 4G100 motor and I'll R & R it with the 165, I had already swapped them out and I'm not about to cut a hole in the bottom of a perfectly good fuel tank.
They would not stand behind their bad advice, the small cost for the 4G100 around $225 was much better than buying and installing a sump, for having a big ass 30-40 hp towtune.

Kennedys don't put of the psi even close to a 95/100, so no you would NOT ever have this problem with a Kennedy LP and the Kennedy LP do NOT have a return line back to the tank like AD and FASS does for the fuel not needed at the engine.

Slightly used 4G165 is in its box incase anyone's interested in a larger AD LP pump motor and installing a sump.
2nd picture 4G100 in place of the 165 using the stock pick-up, no cavitation.

Good Luck on your decisions on what to do, I suggest the easy way, change out the motors if you can.
 

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I run a sump on mine, no issues, easy install. I know a lot of guys are apprehensive about putting a hole in the bottom of their fuel tank, but it is not a big deal at all.
 

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I run a sump on mine, no issues, easy install. I know a lot of guys are apprehensive about putting a hole in the bottom of their fuel tank, but it is not a big deal at all.
Maybe not to you and it’s your truck.
If it’s really not need 'dunno; why, and why go overkill installing a big liftpump when the smaller ones is all you need.

With having a 150/165 lift pump you’ll have 12-13+ psi out of the LP, 8-10 is considered safe for the Dmax.
If you don’t have a psi adjustment on your LP and/or don’t know the psi, you could eventually have issues at the motor.
Even if you install a sump, this does not change the psi out of the LP going to the motor.
No, they won’t tell you guys this when pushing to sell the larger LP.

Just recently one member reported that his was leaking around the gasket, which is expected to eventually happen.
 

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A sump and a lift are both great mods.
Lift, Positive pressure to the engine. Doesn't have to be massive GPH flow numbers. Keeps the main line from loosing prime or collapsing. There is not much opportunity these trucks on the road will ever exceed 30 gallons per hour so no need for huge GPH numbers out of a pump. A lift combined with filter and water separator provides constant fuel cleaning and returning to the tank. By the time an atom of fuel gets to your injectors, there is no telling how many times it has been through the filter system but way more than once. Filter changes become a 5 minute task. If the lift pump ever quits working, using todays modern quick disconnects, it becomes simple to bypass the lift pump.

A sump provides a gravity means of getting fuel from the tank without having to deal with suction or siphon. Sump also provides an excellent way of draining a tank if any chance of fuel contamination exists. Will it leak, maybe eventually but not likely. If it ever does, it will seep, not dump giving plenty of time to run the tank down to empty normally. If it does, with my current setup I could have a new O ring in place in about 30 minutes with a hex wrench.
 

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What psi is your LP putting out going to the motor, I presume you don’t know 'dunno;

To the right of my CTS2 is psi out of my LP.
Just below my fuel gauge is reading psi off my fuel test port.
 

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Injection pumps that are not mechanical do not need a lot of pressure just a steady flow about 20-25 psi, I ran a fass in my P pumped Dodge and it needed 45 psi, when I had the fass with the VP44 it needed only 18 psi
 

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There’s a large difference between Dodge and Duramax with psi requirements.
All anyone needs to do is shop on these LP companies websites to see the variations with psi with all the different manufacturers Diesel engines.
 

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actually no matter what the engine is a CP3 being a three lobe pump with a built in lift pump only needs 10-15 psi at idle, it then converts that to about 150-180 psi which then is used according to the computer to boost the pressure for the injectors, no matter if its a Cummins or Duramax
 

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I read a post somewhere that you can reduce the pressure of the Fass by trimming the recirc non return valve spring.
Is this true?
 
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