tughillnut

i have a fass lift pump only 150gph. my pressure at the vp at idle is like 19-20.even at light throttle it drops to like 10-15. and at heavy wot for a little its at like 5 since i see the light come on all the time. and if i back out of the throttle a little hard it stalls and i have to re prime the system in the middle of the highway. not so funny after ya smoke a rice burner and stall a 1/4 mile down the road. could my lift pump be shot already its like 3 yrs old maybe 4 .never thought it would go so soon.are these pressures normal? i just put in a feul pressure guage finally and now i am worried about how much of a drop in pressure weather i am heavy or light on the throttle. i thought they would only be dropping so much under heavy throttle.any help would be great.

klx650a2

Do you have the big line kit from the fuel filter to the IP? Have you changed out your fuel strainer before the lift pump? Are you getting any codes? Have you swapped out your fuel filter?

I've only got a 95 with no big line kit and cannot get anything lower than 12 at WOT. 15.5 at idle.

robert78.5

Is there a strainer before lift pump?? 2001

klx650a2

There should be a "in line" strainer before the lift pump, keeps the crap out of the pump. My lift pump came with one when I bought mine from Vulcan.

tughillnut

no codes,no big line kit, going to get new fuel filter even though i think its still pretty new i dont really remember and no strainer in line before pump i took it out to see if it would help and no change.other than the strainer in the tank.

Diesel_Storm

Ya, there is a problem there. I have a Holley Blue fuel pump and I see no less than 15 psi at any time.

I do have one question, are you running the FASS through the oem lift pump?

If so I would by pass the oem lift pump and try it again. I just installed a fuel pressure gauge on my truck and was seeing 5 psi at idle, and almost 0 psi at 2000 rpm.

Found the problem was, the PO had routed the frame mounted pump they installed through the stock LP, which was dead, causing a major fuel restriction.

tughillnut

nope i used the new fuel line that came with it and it runs directly to the fuel filter on the engine blockby the vp44. does anyone know if fass remans lift pumps.

Junk Man

My understanding is that FASS has life time warranty at least after a certain manufacture date. I'd contact FASS as I've seen great tech support from them on another forum. I went with AirDog because it was recommended by the local shop. I'm seeing 15-17# which you should see with FASS.

Moose10

Fwiw tughillnut, my 95 HPFP is 4 yrs old and still puts out the same pressure since the day I put it on. Idle around 18.5, cruise at 65mph about 16.5 and and heavy throttle towing the TH uphill at 32psi boost in 4th gear about 14.5 to 15. Still got the same inline pre-pump strainer that came with it.
I wonder if maybe you have a broken spring in the pump? Have the pressures always been like they are now?

Isn't Diesel Dan the resident FASS guru / dealer guys?