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HurtMan
06-24-2009, 08:40 PM
Put in a low pressure fuel gauge (diprocal) electronic. Found out that my suspicions were right only 6.0-6.5 psi out of my Fass 95. Found out that the Fass pump are 12-16 psi. Usually 12 psi is factory set. I'm feeding twin fuelers and +40 injectors. With these bigger pumps 150+GPH pump some came be adjusted to run up to 40 psi. My question is how big do I need to go? How much line pressure should I give it?

When I put in the race tune I can drop fuel pressure too -0- almost immediately.

IdahoRob
06-24-2009, 08:53 PM
Jason, you want to be around 12psi at idle, not much over. The filter/head/cp3/ficm don't like much more. A good flowing pump will still have positive pressure at WOT. Even +1psi at WOT will get the job done.

HurtMan
06-24-2009, 10:43 PM
Thanks Rob, thats just what I wanted to know. Have you seen the HellMann gravity feed for the Duramax? I still need to upgrade the feed straw in the tank any suggestions ???

cetanefreek
06-25-2009, 07:45 AM
keep in mind that the 150gph Fass is only good for 18 psi, which is still fine for your application, however it is the 95/180/200 pumps that can push up to 50psi, any of them would be fine for you though.

HurtMan
06-25-2009, 11:03 PM
I was told there is a spring in the top of the fuel filter that can be lengthened to increase line pressure. Anyone ever messed with these springs? Going to have a look at it tomorrow.

cetanefreek
06-26-2009, 08:29 AM
yes you can stretch or lengthen the spring, it is located inside the fitting for the return line from FASS back to the tank, you will need to disconnect the return line, then take the fitting out of the FASS, there is a spring and a small plastic ball in there, the spring is what determins your fuel pressure.

HurtMan
06-26-2009, 10:00 PM
Thanks, I was just lookin for some information on how to do this mod (with no luck ) So I was happy to see your reply. Would think you would stretch 1/4" at a time? Put it back together and see where psi is. Hate to go to fare to fast. Any suggestions?

HurtMan
06-26-2009, 10:21 PM
Talked to a guy at Fass and found out that the psi for duramax application is 6.0-8.0 psi. I was under the impression that the factory set up was 12 psi (not true). I can drop the pressure to -0- almost immediately. I also had him look up my ser # and found out my pump is a 150 just thought you might be interested in know that if you didn't already know.

cetanefreek
06-27-2009, 08:30 AM
wow, you're dropping the pressure to 0 with a 150? something ain't right there.

how long have you had the unit on the pickup? is it possible you have a plugged filter? I don't know all that much about Dmax's, is it possible that you have a collapsed strainer in the tank like the early cummins used to get with a big FASS?

cummins cowboy
06-27-2009, 03:04 PM
are you running a draw straw?

XMASTREE
06-27-2009, 03:28 PM
are you running a draw straw?

X2...I know i put one in my truck and it made the world of difference for constant pressure!!

HurtMan
06-27-2009, 10:00 PM
I stretched the spring today it measured 1" lengthened in to 2 1/8" it only affected my idle pressure to 7.5 a gain of 1.5 psi at idle. If I kink the return line I can build 16+++ I was thinking about putting a ball valve in the return line it would act just like a fuel regulator adjustable to desired idle pressure. I will put a new fuel filter in Monday just to see what happens the filter thats on now may have 4,000 miles. I'm still thinking I may have a bad pump. It don't make a lot of noise it always been some what quiet. When people that no anything about diesel trucks notice it in the wheel well they usually say man I wish mine was that quiet??????????? ~X(

cetanefreek
06-27-2009, 10:06 PM
valve in the return line won't work very well, it would be flow sensitive, not pressure sensitive so as you got on the go pedal pressure would drop back down to current levels, your best bet would be to either find a stiffer spring locally that is the same size or get a different one from FASS, how much pressure are you wanting? you could get a spring for a FASS set up for a 24V cummins, that would give you right around 16psi.

cummins cowboy
06-28-2009, 01:49 AM
the newer FASS pumps are pretty quiet. I can barely hear my 150 even when the truck isnt running

HurtMan
06-28-2009, 04:04 PM
I might have to see about a cummins spring I'm trying to get 12 psi at idle. I stretched the spring all I dare and only got minimal results 1.5 psi increase 7.5 total. I put the boat behind it today and I was surprised how much I could pull the pressure down to 2 psi in the tow tune. I just couldn't believe that stretching the spring from 1" to almost 2 1/4"only got me 1.5 I would of thought that I could increase pressure to at least 10 psi even if it was for a short period before the spring tension gave in. Any other thoughts I would love to here them. I'll see if Fass will send a different spring, even if I had to cut the 16 psi spring down (trial & eair)

JoshH
06-28-2009, 06:50 PM
Go to a good spring shop. Surely there's one in the Salt Lake area. You might have better luck getting something to shim the spring with, like some washers or something.

cetanefreek
06-28-2009, 08:13 PM
I still say you need a stiffer spring, stretching them doesn't do that much because you are not really changing the spring rate, just the length and therefore the pre-load of the spring.

XMASTREE
06-28-2009, 10:42 PM
i will have a stock dodge spring by the middle of this week as im going to a stiffer one in my truck...let me know and its yours man! it produces 14 psi in my truck at idle!!

HurtMan
07-04-2009, 03:06 PM
I ordered a fuel pressure regulator 0-30 psi I will install it and let you guys know how it turns out. Went to some truck pulls and talked to a couple of guys that where very knowledgeable on the duramax both were runnin fuel pressure regulators. I was planning on leaving the stock spring in and just adjusting pressure on the return side, But I appreciate the offer on the spring XMASTREE don't the dodge need 40+ psi ? Was thinking that spring would look like a spring out of a brake drum assembly.

cetanefreek
07-04-2009, 03:13 PM
94-98 dodge with a P7100 needs 40+ psi, the 98-1/2- 2002 with the vp44 needs around 16 psi

XMASTREE
07-05-2009, 03:12 PM
94-98 dodge with a P7100 needs 40+ psi, the 98-1/2- 2002 with the vp44 needs around 16 psi


Like Russ said the factory spring for the 150/150 on my truck is consistent to 14 psi. The offer will stand so let me know if you need it.

HurtMan
07-19-2009, 01:13 PM
Put in fuel pick-up straw and a flow control still loseing pressure -0- in race tune I think I've got a bad pump????? I stretched the spring with almost no luck 6.5-7.5 that just seems really low. I need volume

XMASTREE
07-19-2009, 03:29 PM
Put in fuel pick-up straw and a flow control still loseing pressure -0- in race tune I think I've got a bad pump????? I stretched the spring with almost no luck 6.5-7.5 that just seems really low. I need volume


Dont know if you've got a bad pump or not but you should get more than that out of the pump...How long have you had the pump? You're still welcome to try my spring in there...stretching the spring really isnt good for much

AH64ID
07-19-2009, 07:30 PM
The stock LP on the Cummins CP3 feeds about 9-11 at idle and 4-6 WOT.. Even with 3 filters I don't go below 5psi with stock fueling... You don't need much to make a CP3 happy.

HurtMan
07-24-2009, 12:57 PM
Ordered a new Air Dog 180-240 GPH should get it in next week. This should solve my fuel issues (I hope). The fass 150 was installed 2/06 I hope I'm just out runnin the pumps volume so I might be able too get a few buck out of it. Thanks for the offer XMASTREE on the spring should find out soon if this works.

HurtMan
08-13-2009, 06:37 PM
Installed a new Air Dog 200 Nice pump the install is a much cleaner design than my old Fass (fuel return) no longer in the filler neck. As for the truck its now holding fuel pressure at WOT. I thought this new pump would be noisy, but it is really quiet, seriously this pump you can hardly hear it!!!

XMASTREE
08-13-2009, 09:32 PM
good to hear man! what kind of fuel pressure are you getting out of it now?

HurtMan
12-09-2009, 11:26 PM
Set regulator at 12 psi at idle. Holds 9 psi at WOT

XMASTREE
12-10-2009, 12:36 AM
Good to hear! glad it is working out for you

HurtMan
12-10-2009, 06:19 PM
Thanks now we can throw the fuel at it.(bigger injectors)