Fuel pressure drops at wot
 

hey guys got a 99 5.9 cummins just instaled a new raptor 100gph and remote filter on the frame ive got 3/8 line from the tank to the remote filter and 3/8 from the filter to the pump with the 1/2 inch line the comes with the pump to the stock filter and i keep getting huge pressure drops a wot.i have my pump set at 20 psi and it reads that at idle but when you go to drive it the damn thing drops below 8 or so:argh: anyone have any ideas on why it would do this at all? ive checked all the lines and there all clear just dont know what to do now and dont wanna burn up another vp44. :argh:thanks

replace the 3/8" line with 1/2" line all the way to the tank

your either need 3/8 all the way, or 1/2 all the way. going from the 3/8 to the 1/2 is where the problem is

The different sized lines aren't the problem. First problem is if you're running thru the stock line with banjo bolts from stock filter can to vp44. Second is running a filter between the tank and the raptor, it isn't needed and is nothing but another restriction.

Would a draw straw do the trick with some 1/2 line from the tank to the pump?

Draw straw wouldn't hurt. with 1/2" to pump, eliminate 1st filter, then either buy vulcan 1/2" kit for between stock filter to vp44 or make your own kit. Then you should be good. I still had pressure drops with mine so I just modded stock filter can.

Thanks guys hope the draw straw and new line works

What kind of filter is before the Raptor? If it is just an inline strainer, it is fine.

I am running my FASS150 to my stock fuel filter, with stock lines between the filter and VP, and my pressure is very strong all the time.

It's a volcan performance 3 micron frame mount filter.

Try putting the filter after the Raptor, not before it. 3 micron is pretty small. A 10 micron may be better if you are keeping you factory filter.