Fuel pump internal/HPFP,really necessary?

R

rmcat

Member
saw ppl recommending them after adding some mods,I wanna be safe and not to blow the engine,but don't know if fuel pump upgrade is really necessary for me

Currently running Cobb SRI/FMIC/TBE(catted) w/ AP stage 2++ 93,car spikes to 22psi in high gears and sometimes having the famous irregular partial throttle KR up to 7.7 but rarely anything under WOT,only had stutter/fuel cut problem when it's very cold outside,but didn't really have low fuel pressure problem otherwise so far

for sure it's gonna be safer to have the upgrade,but is it really worth to spend $400-$800(shipped to Canada)on fuel pump with my current setup?
 
I'm in the same boat as you. I pretty much have the exact same mods as you do. I've datalogged my car with the Accessport numerous times.

With all my current mods, I constantly have fuel pressure in the 1600 - 1700 range with the stock fuel pump at WOT. Only once, have I seen it blip down to the high 1400s at WOT, but never any lower than that.

I'm having it professionally tuned next month and the place I'm going to, which is very reputable tuner, told me that those numbers sound fine. I'm sure I could get higher fuel PSI numbers with an aftermarket fuel pump, but I'm sticking with the stock one and just going to keep an eye out and do frequent datalogs to make sure that its consistent.

Also, I never boost more than about 19 PSI and have no knock whatsoever. If your fuel PSI numbers are solid, then I would just say get a custom tune done to be safe.
 
Last edited:
You don't need it unless fuel pump pressure falls below 1600psi. Get your self a monitoring device like a DashHawk if you don't have one and do some logs. What I read is that sooner or later you will have to upgrade but you will only know when stock fuel pump is acting up.
 
If you're hitting 22psi, I'd seriously suggest taking it easy until you can log fuel pressure. Direct Injection engines are very sensitive about fuel pressure. Think of the $4-800 as insurance against a blown engine if your fuel pressure isn't holding firm at peak boost.
 
get a fuel pump

800 bucks

or

2-3 days of cursing up a storm stocking out and still risking 6k for a new motor
 
A week away from getting my car tuned, I figured I would do some more datalogging to make sure my stock fuel pump is still holding good pressure and what do I see...fuel pressure dropping down to about 700-800 range at WOT.

Guess it's time to upgrade that crap. LOL.

PT-P here we come.

(I'm on the list for recommending this as a necessary upgrade now for anyone with any type of bolt-ons)
 
Last edited:
Yes, you can use the Accessport. Just make sure that you datalog "DI Fuel Pressure". That's the one you want to keep an eye out.

My mistake was that I was mainly datalogging 3rd gear. I never saw the extreme drop off in this gear. It wasn't until I datalogged 4th gear that I saw this dropoff.

Find a good highway on-ramp, get it into 3rd gear and around 3K rpms start datalogging. Go WOT to just about redline in 3rd and 4th if possible.

If you've got a $hitty fuel pump, you'll see the dropoff here. You may need to do this a few times. If there is any drop off in fuel pressure, then you may want to upgrade the pump.
 
With your mods I would def suggest in an upgraded fuel pump.

It's more of a preventative measure...

Oh and retune that boost curve. 22psi is methland.

I would recommend 19-20psi max with out meth.
 
I cant believe how many of you guys still dont understand, fuel pressure doesnt mean s***. 1600 or 1700 psi on a stock pump is junk. All it means is that your pump is keeping up or failing. If you mod your car and want to make any power or get good performance, you HAVE to get a fuel pump or internals. They flow more VOLUME, which is what is important. Its all about volume here guys not the pressure, even though upgraded units flow more pressure as well...
 
Fuel pressure by it's self don't mean a thing correct, you must have flow. The reason the ecu monitors pressure is that it can be done a whole heap easier than monitering flow! Cheaper and easier.
 
bykeryder4life said:
I cant believe how many of you guys still dont understand, fuel pressure doesnt mean s***. 1600 or 1700 psi on a stock pump is junk. All it means is that your pump is keeping up or failing. If you mod your car and want to make any power or get good performance, you HAVE to get a fuel pump or internals. They flow more VOLUME, which is what is important. Its all about volume here guys not the pressure, even though upgraded units flow more pressure as well...
Click to expand...

Please feel free to explain how the same pressure being applied to the same diameter fuel rail by a different pump equals higher flow. I may be a little dense here but that does not make any sense.
 
Chapa said:
Fuel pressure by it's self don't mean a thing correct, you must have flow. The reason the ecu monitors pressure is that it can be done a whole heap easier than monitering flow! Cheaper and easier.
Click to expand...

Heh... No.

The ECU controls the precise amount of fuel that is injected into each cylinder. There are 2 variables that determine that amount of fuel:

1) Injector pulse width.
2) Fuel (rail) pressure.

It's really very simple when you think about it.
 
maestro said:
Please feel free to explain how the same pressure being applied to the same diameter fuel rail by a different pump equals higher flow. I may be a little dense here but that does not make any sense.
Click to expand...

That's what I want to know also.
 
maestro said:
Please feel free to explain how the same pressure being applied to the same diameter fuel rail by a different pump equals higher flow. I may be a little dense here but that does not make any sense.
Click to expand...
Agreed. Pressure down the pipe produces volume.
 
Perhaps i shouldve done this.
Q.Then why is the ECU measuring the fuel pressure?
A.The reason the ecu monitors pressure is that it can be done a whole heap easier than monitering flow! Cheaper and easier.
"Please feel free to explain how the same pressure being applied to the same diameter fuel rail by a different pump equals higher flow. I may be a little dense here but that does not make any sense."
Basically the different pump is a bigger pump so for the same given pressure the flow can be greater.
 
The bigger pump can't push more volume without greater pressure. X psi on Y diameter pipe produces the same volume. Greater volume down the pipe would increase the pressure. Presumably the lines can stand it. Probably not a large increase.
 
Please log in or register to reply here.

Similar threads

D
Both fuel pumps failed (2022 CX-5)
Replies
16
Views
3K
edmaz
E
D
Limited/fixed HPFP pressure, misfire, power loss and can't reach high revs smoothly
Replies
1
Views
2K
ryanjem
R
J
  • Locked
HPFP Stage 2 High Pressure Fuel Pump MS3-MS6 - SOLD
Replies
2
Views
1K
DCMS3
D

Latest posts

Back