Engine/Transmission (1998.5 - 2002) FASS vs RASP

[EGaskamp]

I wanted to get yalls views on both the FASS and the RASP. I desprately need to do something. Whats the best web site to get a Vulcan big line kit? Does anyone have pictures of the big line set up? Would relocating the stock LP to the frame rail at the fuel tank work better until I can afford the FASS or should I just leave it where it is? Thanks for the help in advance.



Eric

 

[rweis]

I relocated my lp to the frame and that definitely helped. However you still have brushes, armatures, thrust washers, and a bypass valve that is a pita.



The reason I went with the RASP:



Mechanical

Higher the fuel demand the faster it is pumping. I idle at 12 psi and as soon as rpm goes up the pressure goes up. Need more got more.



Simple mechanical bolt on

Bracket on the harmonic balancer, 2 pulleys, bracket on the front of the oil pan using existing bolt holes. Cog belt tension easily adjustable (should NOT be tight, it is a COG belt).



Plumbing

YOU have to develop your own plumbing routes



Backup

Uses existing electrical lp as a backup. Uses a hobbs pressure switch to turn on electrical lp if necessary. Electrical lp gets a backflow regulator (set at a very low psi (2 psi ?) so the RASP does not try to push fuel through the lp, but the lp can push fuel toward the engine if the psi drops below 10 psi. I electrically disabled the lp and just ran RASP only for a couple of weeks to make sure the CTD would start correctly without the lp. The lp only runs for about 1 second prior to start when the system psi is zero. Key on, lp starts for a second, psi rises to 7 psi, lp shuts off, psi drops, key to start, engine starts to turn with the starter, RASP starts to pump, engine starts, RASP now at idle, lp in standby mode, engine accelerates, RASP accelerates increasing psi to preset bypass psi, bypass starts to open, psi stabilizes at RASP bypass open setting.



Fuel circulation

I also like the bypass valve concept of the RASP. Fuel has been filtered when it gets to the bypass valve, then excess psi is bypassed back to the tank. The VP bypass is also bypassing cooling fuel to the tank. I feel more of the total fuel gets recirculated and therefore refiltered constantly not just the VP cooling fuel. I did put the RASP bypass on a seperate tank return from the VP44 bypass so the two of them would not compete for flow volume, eventhough the VP44 fuel return is an open ended line.



Prime

I still use the electrical lp to prime and purge the fuel system of air after working on it, changing filters etc.



Pressure regulation

Uses a bypass flow regulator right at the VP inlet to bypass excess psi to the tank. User adjustable (I set mine as close to 13. 5 psi as I could, ie VP44 optimum input psi).



Cold fuel

The RASP is driven by the engine, electrical pumps depend on the torque rating of the motor at that temperature. I feel that the colder it gets the less able the electrical motor is to pump the same psi. I also feel the CTD can drive the RASP regardless of the (reasonable) viscosity of the fuel. I do use Stanadyne in every tank for the VP lubrication. When it gets cold (30*F) here in central FL I do see the output of the RASP go up about 2 psi, the bypass is still set at 13. 5 psi and the VP still sees 13. 5 psi input.



This is what I chose and I like it so take it all with a grain of salt, but it sure does make sense to me to get rid of the electrical motor pump headaches.



Bob Weis

 

[24V-DSL]

What he said... .



Seriously, nice write-up, Bob.

 

[AHire]

I agree 100% with rweis. The main reason i got the rasp is to get the reliability of of a manual fuel pump.

 

[Graphic man]

RASP all the way!!!!!!!



Almost a year now, and no problems!!!..... i love it



i set mine at 13psi at idle and 15psi at WOT



if you get the RASP, get the Big line kit also.

 

[c-hawk]

I have a FASS, but my vote goes for the RASP. I believe it is a much more reliable system then the FASS. If i had it to do over again i would without question go mechanical...

 

[RMecum]

Another vote for the RASP. I've never pulled it under 12 PSI. The harder you push the more it pumps. It's quiet and easy to install. It turns so slow that at idle you can follow the pulley around with your finger. I got mine from OPoole and got the big line kit with the shut off switch so you can leave your lift pump in line for back up. I highly recomend it Oo.

 

[darkhorse]

I wanted to get yalls views on both the FASS and the RASP. I desprately need to do something. Whats the best web site to get a Vulcan big line kit? Does anyone have pictures of the big line set up? Would relocating the stock LP to the frame rail at the fuel tank work better until I can afford the FASS or should I just leave it where it is? Thanks for the help in advance.



Eric

No doubt the RASP is a top of the line solution but it's quite an investment. The Vulcan big line & pump relocation kit does a good job at a fraction of the cost. Pump replacement is cheap & easy.

 

[NWest]

I've been reading up on the RASP, and wondering- if I install the RASP, is it reasonable to forego installation of a fuel pressure gauge?

 

[Graphic man]

I run the RASP with a gage and a autometer warning light hooked to the Hobb's switch, I set the switch to 8psi so if the belt did come off, the factory LP will kick in and the the light will let me know to shut her down.

it's nice to have a back up.