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FASS Problem--need help

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Fass pump pressure

Guys,



I've had the FASS system for about 4 mths, with steady pressure at 15 psi. On a recent drive, fuel pressure dropped steadily over the course of a 50 minute drive. After a rest period, pressure goes up to 10 psi (and actually up to 15), but after a short period, the pressure steadily falls to a dangerously low level.



I checked the fuse underneath and took a cursory look at the wiring--nothing seems burned up.



Does this sound like a clogged filter to anyone?



thanks!
 
I don't have a FASS and have never dealt with one but a steady pressure drop over a period of time does sound like a clogged filter. I would change it and see what happens. Does the unit sound normal?



-Scott
 
SRadke said:
I don't have a FASS and have never dealt with one but a steady pressure drop over a period of time does sound like a clogged filter. I would change it and see what happens. Does the unit sound normal?



-Scott





I thought I heard increased noise from that area of the truck over the past few weeks, but I'm not sure that the sound was the FASS.



Anyone else?
 
Also you might consider:



1. A leak in the supply line from the tank to the pump, or at the pump.



2. Clogged pickup screen in bottom of tank.



3. Bad pump, or leak in the pump.



Just trying to think of what would cause cavitation noise from the pump.



Do you see any leaks?



Possible gauge problem?
 
Shortshift said:
Also you might consider:



1. A leak in the supply line from the tank to the pump, or at the pump.



2. Clogged pickup screen in bottom of tank.



3. Bad pump, or leak in the pump.



Just trying to think of what would cause cavitation noise from the pump.



Do you see any leaks?



Possible gauge problem?



No leaks seen anyware. And I don't think the gauge is bad, given that the pressure readings slowly decrease over time after starting the truck. I don't think a bad gauge would do that. Still not sure if I was really hearing increased noise from the FASS, since I have a air compressor near there for my air horns, but this seemed like additional noise over the usual compressor noise.
 
What name brand gauge are you using? I would change those filters ASAP. How's the truck running other than the low fuel pressure?
 
Cliffman said:
What name brand gauge are you using? I would change those filters ASAP. How's the truck running other than the low fuel pressure?



Gauge is DiPricol. You wouldn't know there was a problem without seeing that the fuel pressure was low/dropping.
 
I would change your filters, and maybe even go asfar to drop the tank and make sure you dont have bunch of junk in the tank and blow all your lines out.
 
Partsman said:
I would change your filters, and maybe even go asfar to drop the tank and make sure you dont have bunch of junk in the tank and blow all your lines out.





I'm going to take the truck up to my shop to get it diagnosed. One of the TDR members told me that he did have a bearing failure in his FASS. And even if I was mechanically inclined enough to drop the tank, I don't have that kind of time!
 
i had a pressure drop on my fass about six months ago. the pressure spring had relaxed allowing pressure to drop. the spring is located at the return line in the pump. you can take the spring out and stretch it about a half inch or i purchased a 20lb sring from doug at advanced diesel and have had no problems since. hope this helps
 
Do you have the pump wired direct to the original ECM wires? If so, the wire could be burning up, and slowly losing contact. If you do, check that, then wire the FASS into a relay direct off the battery.



Skyler
 
Bearing failure

I am the member that had the bearing failure. When I installed my FASS it worked very well steady pressures and I could here it "working" I started having Hard start issues and noticed my FASS only spun up to about 7 psi on initial key, wait to start cycle. After firing it went to 7 psi and hesitated then jumped up to 15 and never left there. Even changed the filter a week before the failure and the system primed quickly. The one thing I noticed during allof this but dismissed was the fact that the FASS was very loud. sounded like well a bearing. After it failed I even told Brad I thought it was a bearing but was uncertain. Sent the unit to Brad actually thinking I must have a blockage in the tank that caused this. Brad called and said I indeed had a bad bearing and that it was very unusual and he was very sorry. He sent the repaired unitback ASAP and even included all new filters. Bottom line is stuff happens and I always judge a company by how they respond to problems. DPP gets an A plus in my book. Anyway thought I would share becaue even as remote as the possibility is sharing problem stories is how we help one another. For the record, I replaced the OEM tank module with a cutom built 1/2" suction line piee and my Fass is quiet s a chuch mouse, I can not here it at all. :)
 
Fass

Something else you might try is drop the tank and cut the screens out of the pick up there are 2 levels of them. It's really worth your time to try this.
 
I'm starting to have issues with my fass. The presure varies from 8-9 psi up to 18-19 psi. Mostly stays 11-13 psi. When it was installed it stayed 14-15 all the time. Going to change filters to see if that helps and then I'll call Brad if the problem doesn't clear up.
 
I have another situation, not related directly to your problem, but related to the subject and figured here would be a good place rather than start another thread.



I have had my FASS system running for about two weeks now. Initial instalation and prime was flawless. I have had two simple problems since then.



The first was no big deal. They sent the unit with a 9 psi spring. I was kinda discouraged to spend all that cash and see the gauge read 8. 5-9 psi.

This problem was easily resolved with a new spring and 5 mins to install. I no have a constant 15 psi.



Now a new problem. My FP gauge has been dancing ever since I installed the FASS. Every time I hit a bump or the transmission upshifts the needle would fluctuate as much as 5-8 psi. I thought the gauge was going bad. I picked up a cheap FP gauge from Autozone and hooked it up to verify the problem. The new gauge danced in the same manner.

I then left the drivers door open so I could see my FP gauge and reached down and grab the FASS and shook it. The needle danced in sinc with each shake.



I got ahold of Brad at DPP this morning and discussed the problem with him. At first he said that it was normal and everybody would get a little needle movement. I said I could deal with a little movement, but 5-8psi is not a little movement. He agreed.

He said that I had a bad ball valve inside the unit. He offered to repair the unit, but I am not willing to give up my truck for the time it would take to send him the unit, have it repaired and returned. So, he offered to send me the replacement part with instructions on how to install it. That was more reasonable. So I have a part on the way.

I will follow up after I get the part replaced.
 
Thanks fourwhls, Since my FASS was new I've had the same problem. With the same response, "its normal". I now have about 7,000 miles on the FASS and its just started to slowly lose pressure as its driven. I plan on replacing my AutoMeter FP gauge with a mechanical one to verify the pressure loss. With no pressure on the gauge I know I still have fuel in the line because I slightly opened the connection at the sending unit and fuel dribbled out. Not residual fuel, but pumped fuel. When my gauge loses pressure it sometimes appears to be less than the customary zero. Sometime when I initially turn the engine to the run position on the ignition switch I will get no pressure but the pump runs. Even with no pressure, the truck starts fine. If I let the truck sit for a while, the gauge starts acting normally again. The filter was changed when the pressure drop started. I still tend to think its the gauge, but now I know I'm not the only one with the huge pressure variations. Thanks again, I never believed they were "normal. "
 
Hey guys, Mike at AutoWorks Diesel, after much hard work and doing some DPP-recommended updgrades to the FASS, diagnosed the problem as a BAD DIPRICOL GAUGE! (I'm not sure if it was the gauge itself or the connection, but I was surprised to see this in a mechanical gauge).



OH WELL!!
 
Thanks for the info. I'm in the process of checking my AutoMeter FP gauge right now. I've hooked up a 15LB. mechanical gauge and teed off the AutoMeter gauge at the sending unit. I've only had a chance to drive a few miles so the only thing I'm sure of at this point is the mechanical gauge has less movement and tends to have at least a LB. more pressure. Lets hope its really this simple. Thanks again. Crockett
 
I just messed around with low pressure for about 2 weeks. It turned out to be my brand new fuel pressure isolator. Might want to keep that i mind while you try and find your trouble
 
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