so i just installed my FASS pump and im wondering if there may have ben previous rail damage. i noticed now with the fp gauge that the smarty at WOT drops pressure by 6-7, so i go from 21-23 down to around 16. when i didnt have the gauge im wondering if the smarty could have damaged the fuel system any cause stock fp is around what? 8? so at WOT withoutthe FASS the smarty would drag the fp down to maybe 1-2? what could that do to the truck? damage caused by doing this? thanks for the help.

 

What pump to you have the 95 or 150 gph???

 

i have the hpfp 150

 

Id call fass and talk to them I dont think you have rail damage, I have heard of guys getting bad pumps out of the box, there customer srevice is pretty good at Fass

 

I should only drop a few psi the smarty does want alot of fuel what levels are you running have you tried some diff setting??

 

currently running sw5. i just installed it saturday... but before i was on the stop pump running it and im wondering if i have any rail damage from running it on stock and dropping the pressure down to like 1-2.

 

I don't think there's much damage you could do to the rail itself. It's really just a hollow cylinder that supplies/distributes fuel to the injectors.

The only damaged rails I've heard of are from severe fuel contamination.

 

well, smarty doesnt add pressure so this tells me its the fass, are you the first owner of this truck did someone else run a pressure box on it?? if not talk to fass

 

i just added the FASS. why would the FASS cause rail damage. im asking if i could caused any previous damage to it before i started running the FASS. previous owner ran a edge juice with attitude..

 

WELL....21-22 PSI is about 3-4 PSI higher than what we usually see on our test bench here. Most HPFP pumps are about 18-19 PSI. (That is what you have right? Pump with no filters?) I would double check your gauge just to make sure. If you are that high....it wont hurt anything on the truck or on our pump.

From what we have seen, most pressure drops under WOT are caused by 2 main things:

1: Restrictions on the suction side of the pump or anywhere before the gauge tap (Dirty Filter)

2: Gauge error. Especially if you run an isolator and even electric gauge.

I’m not saying this is the only causes of issue….but the main ones.

BUT 16 PSI….you are doing just fine…you have way more fuel at your CP3 than you need.

You can not damage a CP3 by putting low pressure to it…they are designed to take it…..as in stock Duramax applications….Its just the CP3 that pulls the fuel from the tank…..no lift pump. The only items that usually cause issue in a common rail setup is the FCA valve in the CP3 or injectors….other than that…..these systems are pretty reliable.

 

thanks dan! i think i have air in my gauge line. so ill be bleeding that sometime this week. nice product, truck is running pretty strong with it so far. i noticed today when i was around 80 mph/2500 rpms- usually the truck feels like its falling on its face or running out of fuel... not anymore, runs great. fp had me alittle scared, but after hearing it should be around there its cool. its actually dropped since i first installed it. it was reading 23 when i first hooked everything up, now its down around 20-21. i take it the gauge is working itself out?

 

low pressure will not damage the rail. high pressure will damage the injectors. smarty wont damage anything, you are not running higher rail pressure that stock unless you have a beta 4.3, 4.4 from bob wagner. even then, your pressure wont damage the rail. the rail is not associated with lift pump pressure. try not to get things confused.

 

another question for you- as i get lower on fuel(fuel lights on) will my fp fluctuate? cause i was watching my gauge at idle and it would go from like 21 to like 6 then back up. air in the gauge? plus you said the pump should flow around 18-19 psi, mines over 20 psi... is it the pump or is something wrong with my set up?

 

Yeah...if you run your tank that low that your fuel light is on....you will get fluctuations due to the fuel sloshing around the draw tube. I would not suggest lingering when choosing a fuel station at that point.

The pump can handle the pressure and your truck can as well. You might have a tighter spring than normal as our springs we use have some +/- error in them.

 

station is right up the street. im going on my lunch break. just figured id ask. thanks for getting back to me dan. also, nice product! no complaints so far and it def helps the truck stay nice and smooth at higher rpms/speeds