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

[PKemp]

Technical specs are 17 to 22 psi at idle and 25 to 35 psi at WOT for the output of the mechanical lift pump. Those aren't the specs for the injector pump. The mechanical pump also delivers pulsating pressure where the FASS delivers constant pressure. The P7100 will run fine down to 8 psi according to Bosch. Below that it will starve and kick, spit and miss. You're okay..... You won't pull it down using the FASS. The higher pressure of the mechanical pump compensates for its pulsating pressure. A steady 15 psi at any throttle position (FASS) is like comparing niagara falls to a garden hose (Mechanical Pump). 15 psi is good... ... ... You can shim the spring if you like on the return port to the FASS if you're still uncomfortable but it isn't necessary.

 

[Highfinance97]

well at 2000 rpm it should be at 25-30 psi well when im on the highway at 2000-2500 WOT my smoke starts to clear up. so am i starving the injection pump then???

 

[PKemp]

Are you winding out at 2500 rpm? Or is that just when the smoke starts to clear up. I see you have a 4k spring kit in your sig. Are you still pulling? Is there any feel of a miss over 2500 rpm? Or loss of power? You should pull up to about 3300 to 3600 rpm with a 4k kit depending on your plate. What plate do you have? You may be defuelling because of the plate if your not still pulling... . But I still don't believe you have a problem. The Overflow valve will still just dump excess fuel back to the tank anyway.

Regardless, if you are uncomfortable with your pressure you can shim the spring on the return port of the FASS... BPonci can explain that one to you. He knows his stuff... .

 

[Highfinance97]

I think the smoke starts to clear up at 2500-3000 still has LOTS of pulling power. EGT's bury my gauge at 2000

I dont know what plate it is, AUTOWURKS DIESEL made one for me

If i shim the FASS will it shorten the life of the FASS???

Should i put the mechanical pump back in along with the FASS??

 

[PKemp]

You don't need to put the mechanical pump back in. You won't harm the FASS by shimming it as long as you stay under 30 psi :-laf

Really, if you want to shim it keep it under 25 psi. But from what you describe you dont have to do anything. You have more than enough fuel, specially if your EGT's are so high. You need more air (twins maybe) not more fuel, before you melt your exhaust manifold. Is your Pyro pre or post turbo ? With that kind of power perhaps switching to synthetic oil as well (doesn't break down as fast or as much under high heat loads, specially for your turbo).

I'd find out what plate you have if you can. That info will be very handy to say the least, and where it is in the housing relative to stock. Check with the Autoworks people on what they did.

Do you have the 95gal, 95/150gal or 150gal FASS. If you have the 95/150 or the 150 make sure you have the larger pickup line into your tank. The stock fuel pickup line is too small. It doesn't seem to be affecting you though since your pressure is a steady 15psi under any load. If it was a problem you would be loosing pressure. Think: FASS = Constant Volume under Constant Pressure that you can't pull down. The pump will get all it needs. Remember too though while your knocking back a cool one that lots of black smoke at high rpms means high EGTs and lots of raw fuel being dumped (unburned) out the exhaust pipe to no usefull end... . except burying the "riceburner" behind you..... fun though... . :-laf Also if you live in a snow/ice area where they salt the roads, wash down your wiring under the truck from time to time and put dielectric grease in all the connectors to slow down corrosion. Make sure your wiring is protected and in good condition for this is one of the drawbacks of the FASS. Break a wire or let your connections get bad and your dead in the water. No fun on a muddy road in the freezing rain.

 

[Highfinance97]

pyro is before the turbo

I have the 150GPH and i did not put a bigger line in the tank (yet)

ill called autowurks Again and mike said he wouldnt be able to actually tell what plate they made. the just made it according to the rack travel

If i was to put a different spring in the fass or shim it where would i get the correct spring or shim so i would see 25PSI??



kemp thank you VERY much i appreiciate all the help you are giving me



Michael

 

[PKemp]

Go to: http://www.dieselpp.com/[url/] for ...ally good knowledgeable people on here. :D

 

[EBottema]

To each his own but for the most part there is no reason to run a elec. pump vs the mechanical pump on the side of the block. It might be better to have a steady flow on w/ elec. pump on a race engine, but again we crossed that driver/race line by using a race engine. I pick reliablility, cost, and simplicity. Mechanical pump

 

[PKemp]

EBottema: You are as others would run to confirm, absolutely right. In most all cases the mechanical lift pump is considered almost bullet-proof. If you are running a P7100 pump of any model or configuration there is no reason to go to the FASS other than being peculiarly eccentric (this is where I fit in :-laf ) or have enough money to burn a wet dog. The FASS compared to the Mechanical Pump is indeed an expensive alternative and has its own problems as well as additional maintenance. I wouldnt recommend it to the hard working daily driver. But that wasn't what this thread was about. If you have a VP-44 injection pump though thats another story.

I'm goin back fishin, just stopped in to peek... ... . Fishin is good...

 

[Highfinance97]

Im waiting on a supposedly 25PSI spring for the FASS. so hopfully it will be 25PSI so i wont be worried about starving the pump



Michael

 

[PKemp]

Michael,



Just checking to see how its going. I see you ordered a 25psi spring. I hope that aleviates your concerns. You could do the same by putting a washer in the return line fitting. If you remove the fitting marked "R" on the FASS, (3x4 inch wrench) carefull also this is a brass fitting in an aluminum housing, you will find a rubber o-ring on the fitting, (put some oil on it when you put it back together), also you will see the return valve spring and a composit ball the seats against a bevelled opening in the return line bore. Simply make sure the ball is in the hole, insert the new spring, the brass fitting and torque to 35 ft lbs using a 3/4" socket (no more, remember: Brass and Aluminum)...

You can just b put a brass or stainless steel washer between the spring and the brass fitting. You would need a metric washer with a 10mm center hole and an outside diameter of 17mm. Home Depot and Lowes have them in thier speciality hardware sections ($1. 06 for a pack of 6). I needed only one stainless steel washer to raise the pressure from 15psi to 23psi. Its not an exact science and you may have to play with it. But since you ordered a new spring use it instead.

Most people don't use the FASS on a 12valve because of the mechanical pumps reliability so the FASS usually comes set up for the VP-44 pump. 15psi for the VP-44 is way more than adequate on even a race engine. However, I've been running FASS units on 12 valves for a good while, all set at 15psi. Some for fun some under extreme work loads with never a problem and no mechanical pump. Its been an ongoing experiment shall we say into technology. But as EBottema pointed out a FASS on a 12 valve is like putting perfume on a hog :-laf . Its pretty cool, really makes the P7100 happy, can increase your fuel mileage and peformance a little, but isn't really necessary.

I hope your nerves are calmed a bit. Have fun, drive fast... . My fish are bitting and the boats leaving. See ya later.....

 

[Highfinance97]

Well i ordered a spring but they called me today and said i should shim it with a nylon washer. So i guess i might be doing some experimenting with shims if i go that route



Kemp thanks again, Oo.



Michael Oo.

 

[PKemp]

Michael,



I gave you the wrong wrench size for the "R" fitting on the return line. Its a 7/8" wrench and socket..... Sorry, had fishin on my mind, wasn't thinking.....

By the way I have used nylon washers before but just like the stainless steel and there are more different thicknesses available in metal.

By the way pursue those guys at Autoworks Diesel about your plate. That wasn't a good answer they gave you.



:-laf