FASS on...high pressure...will it hurt anything?

[steved]

Well got my FASS 95/150 on last night... at the CP3 I'm getting 25-26psi! :--)



What is everyone else getting for pressure and will this hurt the CP3 in anyway??



I haven't read any other posts about detrimental effects of too much pressure, only that pressure isn't needed (only volume) and the detriments of no pressure.



Any thoughts??



Thanks,

steved

 

[JVolpe]

Mine is 18psi idle, never any higher. Usually 15-17psi cruising. WOT at the track pulls down to 13psi and slowly creeps back up to 15psi.

 

[steved]

Hmmm... I have read that the FASS tend to wear in after a few days... and the fuel I'm trying to pump is around 10*F (so it might be a little thicker)...



Just don't want to damage the CP3 if you know what I mean...



steved

 

[JVolpe]

Actually now that you mention it, when temp was below 45* a few days ago I did notice 19-20psi for a few minutes when first started. I am sure the temp will have some effect, just don't know how much or for how long. Rarely ever gets to 32* here.

 

[steved]

Rarely ever gets to 32* here.

You lucky devil :-laf



I know that on the 99, when it was warm (summer) it idled at 10 psi and in winter it idled around 16 psi... that was a factory LP.



One thing I noticed is that this is the new version of the electric motor... no external brushes to replace... good for a million miles (??)



I also noticed that several people claimed encessive noise in their cb's... I have less noise now than with the original (factory) LP... but the pump itself is very noisey... I can see where people with factory exhausts don't like them... I'm pretty much straight piped and I can hear it over the exhaust.



steved

 

[banshee]

No problems with that pressure. I've been pushing that much and more to mine for over a year and half.

 

[jwilliams3]

When its cold out, which is all the time now I am getting around 30psi on start up and when the fuel finally warms up around 18psi.

 

[steved]

Well, that's good to know. I was worried that the excess pressure might do something detrimental... but I guess the CP3 does have a return line to the tank so it should pass any excess fuel back to the tank.



Another question... what are you running (if anything) for a fuel heater?? I was trying to figure something out, but nothing was simple... really don't want to run coolant lines to the FASS... and I guess I don't even know if it is or when it becomes needed (when running antigel).



Thanks for the replies,

steved

 

[jwilliams3]

No fuel heater here.

 

[JVolpe]

You lucky devil :-laf



steved

Well double edged sword, stays above 90 for most of 6 months also. :-laf . Of course I am in shorts today and can play golf all winter, that is if I could afford it anymore. The BOMB bug has limited some activities .

 

[steved]

Well... after driving this thing for a few days all I can say is WOW!



I find it amazing how a simple pump and filter set up can make some good overall changes! I have put about 500 miles on it so far and I can see three very apparent things: I have a smoother idle, seat-of-the-pants dyno indicates a smoother power and maybe a wee bit more top end (it now smokes every gear when applying power), and my mileage is up maybe 0. 5 to 1. 0 mpg... very happy with these results... and this is an almost stock truck.



I have no doubts that I'm over 20 mpg at 65mph or 2150 RPM (I was at 19. 5 mpg at 60mph or 2k RPM). And overall the truck runs/feels better...



And the pressure has dropped to 23. 5 psi, but it has warmed up to 60*F also...



I have a couple more questions... when you installed your pump, did it contact the filler tube?? My tube is resting slightly on the electric motor. And, what did you do with the hoses from the old system?? Mine are in plastic bags (temporary) at the moment... did you take them off?? Leave them as a backup?? What about the fuel heater?? Did you disconnect it????



That is the ONLY thing I did not like about the FASS... lack of instructions big time... there were no instructions for the low fuel pressure light (not that it was hard to figure out), but... And then like my questions indicate, there is no further direction regarding the fuel heater or old fuel lines... I was going to make a nice clean job and remove the old filter housing... except it also acts as a manifold for the fuel return lines... DPP sorta leaves you hanging in that respect.





steved

 

[mhlbr]

I put my 150 FASS on before I ever put anymore power to it. Saw about 16PSI at idle. It drops to about 14 at WOT now. Pressure isnt the issue its volume IMO

 

[steved]

Well, this was interesting... I posted this question on another board and was told anything above 15psi was hurting the CP3. He gave NO explaination, just made the statement.



Anyone else know why it might hurt the CP3??



Oh, and I'm ordering the "13psi" spring kit for it



steved

 

[mhlbr]

Steve,

I have had my FASS on for going on 35K miles now. About 25K of that was a bone stock motor, 8K was with the edge ez/edge juice and now the last 2K with twins and no changes to the cp3 pump. Thats why they made a return line to your tank. What other forum was that??

 

[steved]

Steve,

I have had my FASS on for going on 35K miles now. About 25K of that was a bone stock motor, 8K was with the edge ez/edge juice and now the last 2K with twins and no changes to the cp3 pump. Thats why they made a return line to your tank. What other forum was that??

See, that's how I see it too, the return line should put any unused fuel back to the tank (albeit, it can't put all of it that the FASS supplies back to the tank, but it should not hurt the CP3... the only thing I can think it might do is physically cause the CP3 to leak (blow a seal) or something???



The other forum was www.thedieselgarage.com . There are some east coast guys on there.



steved

 

[rbattelle]

Well, this was interesting... I posted this question on another board and was told anything above 15psi was hurting the CP3. He gave NO explaination, just made the statement.

This guy might have read that on here. Somewhere there's a thread (of course, I can't locate it now), where someone reported talking with a guy at Cummins who commented sort of "off hand" that 15psi is a good number for an "upper limit" on fuel pressure at the CP-3 inlet. I don't care if it did come from Cummins - I no longer accept that number as fact.



For a long time I worried about running excessive pressures and ruining the fuel control actuator (FCA). But there's a large (and growing) body of evidence indicating that pressures even up to 25 psi are not harmful in the long-term. Nevertheless, remember that volume is paramount - not pressure. I've tried to engineer my system to run at minimum pressure at 60-90 GPH.



There was a thread started about this, but it sort of fizzled out. Link.



When I had my Aeromotive pump the pressure would increase as ambient temperature decreased. Now with my Holley Blue the trend is exactly opposite. In warm weather I idle at about 12. 6-13. 0. In cold weather I idle at 11. 6-11. 8.



-Ryan

 

[steved]

Thanks Ryan,



I had read that thread you were looking for and basically it went down in flames... almost everyone that posted indicated they were running high pressures without issues... the thread originator got slammed pretty hard in that thread if I remember correctly.



I'm going to order the 13psi spring Monday, hopefully it gets here before I leave... going to either SC or OK next week sometime! Oo.



You can imagine my surprise when that response was posted... of course when he made no supporting conclusion about that statement, I sorta was like, ummm .



I took it out again last night and it runs absolutely great... and the fuel mileage gain is there regardless of fuel... I got just shy of 20mpg (on winter fuel), and theat was driving to work one day (about 50 miles of stop and go traffic) so I feel really good about the gain... between the FASS and the RokkTech sensor, those are the two single best mpg mods you could do IMO.



steved

 

[steved]

Well, I ordered a 13 psi spring for my FASS... replacement was easy... thought I was going out of town so I had it overnighted... $24 shipping :{



But, I now have a more reasonable 12-13 psi at the CP3... I have a low pressure light on it too, so I can see if I'm pulling the pressure down to under 7 psi... after some very hard runs, it never flickered the light so I'm happy now.



The FASS also seems happier... less straining because of the higher pressure.



The FASS manufacturer really irks me though... how hard is it to make a consistant product? Mine obviously had the wrong spring in it (thicker wire). They sent me the wrong filter. No instructions for the low pressure light. Installation instructions left you hanging... no "what to do with the old system on your truck" section... nothing about unplugging the fuel heater (wonder if this would cause a fire??).



All in all a very nice product, but they have really poor quality control. You basically get a pump, then you buy the pieces to "customize" it to what you were supposed to get!



Oh, and the guy that stated the higher pressures were bad... he was basing that off from what the Duramax guys are running into... the CP3 on the DuraMax is VERY similar, but not the same it seems... different shaft seals and different internal passages... the DuraMax seems to over pressure the CR which then causes issues... so that is where that came from. . another response was that 15 psi was good with 45-50 psi "when you need it"... whatever that is supposed to mean. I think the difference might be that the dodge CP3 was designed for an external "booster" pump whereas the CP3 in the GM was not... add a booster to that one and you have issues??



steved