Engine/Transmission (1994 - 1998) FASS with no lift pump

[Highfinance97]

FASS with no stock lift pump

so here is the new thing that has me worried , i was talking to piers and he told me that i should not be able to run a FASS system on my 12 valve without the mechanical pump. Because there is not enough pressure well for the past year or so i have been running a 150GPH FASS straight to my injection pump and no problems whats the deal what kind of pressure does a 12valve need and what does the FASS push???



Michael

 

[JGheen]

That is odd, I too have heard that you eliminate the lift pump when going to a FASS system.



Joe

 

[PKemp]

I have the same. A 150gph FASS and no lift pump. Runs fine..... Whats the deal ?

Part of the installation process routes the fuel lines into the pre filter/fuel heater and completely bypasses the lift pump.

 

[Highfinance97]

I still havent heard anything about this can someone enlighten me???????????????

 

[Bob4x4]

You should have at least 25 psi I would prefer more The pressure may have been set on your FASS before you got it.



Bob

 

[BPonci]

The prescreen is on the suction side of the lift pump so the fuel still runs thru it. You can bypass the mechanical system but you have to shim the pressure relief in the fass unit on the return port.

 

[Highfinance97]

the truck still smoke like a ******* and doesnt lose any power, unless i never felt that little bit of power ill have to get a fuel pressure gauge





Michael

 

[BigBadDodge]

Perhaps Piers was talking about in conjuction with his stupid pump, were you talking about pumps ? I know you need more fuel to take advantage of the stupid pump, most are double feeding the stupid pumps.



BBD

 

[Highfinance97]

scott if i read you right we were just talking about how i eliminated the mechanical pump and i have the FASS going directly to the injection pump



What do you mean by a stupid pump ive heard that before but.....





Thanks Michael

 

[JGheen]

The "Stoopid Pump" is a modified P7100 that flows a heck of a lot more fuel than a bone stock pump. Not sure what is exactly done to the Stoopid pump but I am sure it has been gone through and re-worked to feed the extremely large injectors that some of us run around here.



Joe

 

[Highfinance97]

autowurks did the internals so im sure its kinda close to what piers does, but maybe not as much



Michael

 

[BigBadDodge]

Correct the stupid pump is pretty much a maxed out unit with different cam profile, plungers, barrels, DV/s etc... Mine was flowing 820cc's when I left Piers place last April, unfortunatly that was way to much so I have the plate slid back half way. I still use the stock system in conjuction with the Haisley aux sytem the haisley system enters were your overflow valve so there is fuel entering both ends of the pump, there is plug that is removed on the same side of the overflow valve but toward the back of the pump which then becomes the return. wala, two systems, one to fall back on.



BBD

 

[Highfinance97]

So back to the original question What is the deal with people telling me that i cant run my fass directly to the injection pump eliminating the mechanical lift pump what the fass pressure and what does my 215 pump require ?? maybe i should get a fuel pressure gauge





Michael

 

[PKemp]

17 to 25 psi is plenty. the 25 psi is better. The FASS will give you a constant supply at a large volume which is better than the mechanical pump since the P7100 really likes a steady fuel supply. I now have the "Ford adapter" to connect my lines directly to the injection pump completely bypassing the cummins fuel filter assembly, lift pump and fuel pre filter/heater assembly. I have an oil filled fuel pressure gauge (www.northerntool.com) attached to a "t" directly in the line behind the injector pump (no need for a snubber). I have a constant 23 psi fuel pressure regardles of where the go pedal is. It can't draw down the FASS. Engine "sounds" better and "feels" better. The fuel pressure return from the pump is unmodified and working well. The FASS has its own fuel bypass back to the tank in case line pressure exceeds the 23 psi. Works really well. I used to run it thru the fuel heater to the inj pump but I don't need the heater here in South Mississippi. It doesn't get cold enough and I eliminated a possible "air leak" problem. I use the marine grade fuel lines . I don't see what all the controversy is. It works just dandy! :-laf

P. S. The nefarious "tick" is gone also... ... ... . Oo.

 

[Highfinance97]

thanks Kemp everything there sounds good to me, ill have to get a fuel gauge(200$ wow)



do you have any pix of what you did?????



also what do you mean by The nefarious "tick"???



Thanks Michael

 

[PKemp]

Sorry, no pics. A digital camera is on my xmas list though. The mechanical lift pump has always been a source of mysterious noise on the driver's side of the engine. Spring tension in the pump gets weak or the push rod wears more in one spot and you hear a strange ticking noise. By the way your local cummins dealer can get you the part number of the "ford adapter" to connect your lines directly to the inj pump. Most large UPS trucks have a ford chassis with a cummins motor and ford routes the fuel lines over the top rather than behind the fuel filter. So I borrowed the idea, nothing new just adapted something already around that works very well. We see a lot of UPS trucks in our shop so we "steal" what works. We put the fuel line in a kevlar sleeve from Auto Zone that keeps them from getting abraided or chaffed - works... I'll find the part number for you and post it as soon as I find it. Its a dealer part number. I haven't found it anywhere else. Although I seem to remember a post in here somewhere about it... . Try "search". . Another note about kevlar. You can buy kevlar cloth if you've a mind to and wrap your lower aftercooler hoses with it to keep the body from chaffing them causing a pressure leak and loss of boost and power. Thats another thing we do to the UPS trucks. Not attractive but cheap insurance.

 

[Highfinance97]

thanks kemp ya when yoy get some pix and some part #'s PM me



thanks again Michael

 

[Highfinance97]

Installed the gauge

Yesterday i installed the fuel pressure gauge on the FASS. Oo. no matter where the pedel is it stays at 15 LBS. when i let off the pedel it will jump between 15-17 LBS and go back to 15. should i put a higher pressure spring in since there is no mechanical lift pump



Michael

 

[PKemp]

Not unless you really want to. You could "tinker" with the springs but to what purpose? They key is constant pressure at a high volume. I don't believe you'll be able to draw it down or starve your injector pump. The mechanical pump would drop in pressure as you "bend" the go pedal, the FASS wont. Smile - Go Fast!!! From your sig it seems to me you've got air flow/fuel flow pretty well ironed out. Maybe twins in your future? I'm jealous... ... . :-laf

 

[Highfinance97]

i was told my injection pump needs i think 25 psi going to it . so now what??



Im going crazy with this thread I just dont know LOL



Michael