i got my fp gauge install this weekend and was wondering if my readings are right. at idle i get 14-15 but really goin hard with the race and bddl turned up i can lug it to 10-11psi....is this normal?

 

Are you taking the reading before the filter or after the filter before the CP3? A stock intank LP is normaly 9.5 to 10 Psi at idle and can get down to 5 Psi under load taking the reading after the filter and before the CP3. It looks like you are taking your readings before the filter. Normal I would say.

Never mind, I see you have a FASS. You should be good to go... I would love to have 10 Psi under load. Looks fine but some of these guys with FASS pumps should chime in.

 

i put a "T" in right before the cp3 and i do have the 150 fass....

 

Sounds low to me. I have always heard you don't want it to drop below 20 or you're starving the cp3. I have mine set at 32 at idle but since my guage is mounted on the stock filter housing, I don't know what it goes down to under WOT. I do have a rail gauge in cab though, so I at least know it's keeping enough pressure to fee the cp3.

 

Seems low with a FASS even from idle. How long has it been since you changed your filters?

I've got my Glacier tuned to 32# at idle and under WOT it barely goes below 30

 

I have a billet fuel filter cap from geno's, that's where I take my readings. I see 25-27 at idle/no load and 20-22 at WOT. I want to get a T put in pre CP3 and a rail guage, but time and money are things that I do not have...

 

you can change the spring in the FASS pump to turn up the fuel pressure, it sounds a little low to me

 

i havent changed it in about 6k or 6 months....

 

how do i change the spring?

 

Is your gauge there, or just a fitting that runs line to a guage? If it's cap mounted like mine, how would you know what it is at WOT?

 

I have my fp gauge plumbed to a Geno's lid as well. It has an 1/8 NPT port in the top of it. You just run line from there to an isolator or to your electric sender and into the cab into your gauge.

The dropping below 20 is meant for rail pressure. You don't want your rail pressure to drop below 20k PSI or you start losing HP. As far as supply pressure to the CP3 you don't want any less than 10-12 PSI in my opinion under WOT. I have 18 at idle and it will drop to 15 WOT but my rail pressure never drops below 25K. That is with the EZ on level 1 and the Hot Juice on level 6.

 

so will changing the filter out give me more pressure?

 

I don't believe it will unless it is severely clogged. Maybe Diesel Dan will respond to this thread with some info. I don't see a problem with your pressures personally.

 

I doubt it, but it is worth a shot. maybe you got a bad batch of fuel

 

Yeah, but that's with the EZ on. I bet if you unhooked the EZ, 12psi wouldn't allow your stock cp3 to keep the rail above 20k. I still believe without a pressure box and with a stock cp3, you need to maintain over 20psi from the lift pump. But I've been wrong before.