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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Low fuel psi with upgraded pump



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      06-28-2016, 12:56 AM   #1
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Low fuel psi with upgraded pump

As the title says. I upgraded from fuel it's s1 kit to Chris at boost concepts 450 LPFP and ever since than I've been having a low idle psi. Before it was 65 idle, now it's at 45-50psi.chris and I have swapped out 3 pumps now and no luck at all. Fuel filter, fuel regulator and low pressure fuel sensor all has been replaced. No kinks in the line or anything. Only other thing left to replace is the fuel controller module known as ekp. Weird thing is when I throw in a stock fuel pump and my old s1 pump connected with, psi is at 65.turn car off, swap pump to 450 and back down to 45-50..idle voltage is between 4.8-7 idling, anyone deal with this issue before

BTW no codes of any sort, no weird issues, drives fine, starts fine, running E60 in tank with Trebila custom tune. No missing, nothing!
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      06-28-2016, 08:34 AM   #2
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Bumpty!
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      06-29-2016, 06:40 AM   #3
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Bump

Anyone know If I bought a used low mileage fuel module Controller on eBay will it need coding? My car has 96k and the module I was looking at has 36
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      06-29-2016, 05:03 PM   #4
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Quote:
Originally Posted by mojobmw_e90 View Post
As the title says. I upgraded from fuel it's s1 kit to Chris at boost concepts 450 LPFP and ever since than I've been having a low idle psi. Before it was 65 idle, now it's at 45-50psi.chris and I have swapped out 3 pumps now and no luck at all. Fuel filter, fuel regulator and low pressure fuel sensor all has been replaced. No kinks in the line or anything. Only other thing left to replace is the fuel controller module known as ekp. Weird thing is when I throw in a stock fuel pump and my old s1 pump connected with, psi is at 65.turn car off, swap pump to 450 and back down to 45-50..idle voltage is between 4.8-7 idling, anyone deal with this issue before

BTW no codes of any sort, no weird issues, drives fine, starts fine, running E60 in tank with Trebila custom tune. No missing, nothing!
Isnt there another fuel filter on the other side of the tank? Perhaps its clogged/dirty
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      06-29-2016, 05:09 PM   #5
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Quote:
Originally Posted by Banana Clipper View Post
Isnt there another fuel filter on the other side of the tank? Perhaps its clogged/dirty
That wouldn't make it work with the stock pump and not with the new pump.

If it's not a leak then it sounds electrical, or the DME is for some reason commanding a lower pressure.

What's the longest you've driven it with the new pump, without clearing codes?
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      06-30-2016, 12:06 AM   #6
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Quote:
Originally Posted by Banana Clipper View Post
Isnt there another fuel filter on the other side of the tank? Perhaps its clogged/dirty
It has been replaced, also replaced low pressure fuel sensor. No luck. Ordered a used module on eBay to try out
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      06-30-2016, 12:08 AM   #7
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Quote:
Originally Posted by ferocity02 View Post
That wouldn't make it work with the stock pump and not with the new pump.

If it's not a leak then it sounds electrical, or the DME is for some reason commanding a lower pressure.

What's the longest you've driven it with the new pump, without clearing codes?
I have auto clear enabled, but I've done about 100 miles and no diffrence.il be plugging in the bav cabke and hopefully it can read the control module for shadow codes and such
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      06-30-2016, 05:28 PM   #8
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Did you try resetting adaptations? That's what I had to do after putting my pump in.
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      07-01-2016, 08:03 AM   #9
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Quote:
Originally Posted by bigdnno98 View Post
Did you try resetting adaptations? That's what I had to do after putting my pump in.
Yes I did. I also reset fuel trims on bav cable, and on jb4. No difference
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      07-01-2016, 10:51 AM   #10
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Please note, the pumps tested perfect in my own car after the second one was sent back with the same issue... read, not a problem with the pump

He was comparison testing with a stock pump AND the stage 1 still connected. we verified that at idle in my car there is a stable voltage output of 7.57-7.61 volts, while his voltage output was erratic between 4.7-7 volts. My reasoning for why the stock pump and stage 1 maintained a higher pressure at lower voltage was due to the reduced pressure differential of the second inline pump ran in series. he did not test with a regular single stock pump or my guess is his pressures would have been even lower then what the Walbro 450lph single pump put out.

Just wanted to clarify with some additional information!

mojo, I hope the controller module does the trick for you!

Best Regards!

Chris
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      07-01-2016, 12:42 PM   #11
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This sounds like there was not an apple to apple test. If that is true, I wish people would provide comparison information that is valid. I was considering buying this upgrade but started having second thoughts after reading this.
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      07-01-2016, 01:08 PM   #12
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Quote:
Originally Posted by Rickygst View Post
This sounds like there was not an apple to apple test. If that is true, I wish people would provide comparison information that is valid. I was considering buying this upgrade but started having second thoughts after reading this.

Ricky,

Like we discovered the issue resides in the voltage issue where ever that is stemming from, hopefully it is the controller and will be corrected after his replacement arrives and is installed. The pump currently in his car I personally put in my car and ran with an E65 mix to test to make sure there were no issues and it was flawless. It should also be noted (knock on wood) this was the first and only issue that has been brought to my attention and turned out to not be an issue afterall. They have proven to be rock solid performers and mine after a year of use when removed for the test was in perfect condition and was put back in without incident or change after the test was completed.

Chris
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      07-01-2016, 01:35 PM   #13
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Quote:
Originally Posted by Chris@BoostConcepts View Post
Please note, the pumps tested perfect in my own car after the second one was sent back with the same issue... read, not a problem with the pump

He was comparison testing with a stock pump AND the stage 1 still connected. we verified that at idle in my car there is a stable voltage output of 7.57-7.61 volts, while his voltage output was erratic between 4.7-7 volts. My reasoning for why the stock pump and stage 1 maintained a higher pressure at lower voltage was due to the reduced pressure differential of the second inline pump ran in series. he did not test with a regular single stock pump or my guess is his pressures would have been even lower then what the Walbro 450lph single pump put out.

Just wanted to clarify with some additional information!

mojo, I hope the controller module does the trick for you!

Best Regards!

Chris
Yes thank you to Chris for helping out over the last few weeks, he became my favorite person to email. Everything he noted is true and is correct. Looking at his voltage at idle vs mine on the same pumps was a dig diffrence. So with his help and such I ended up getting a used less miles module that arrives today and hopefully gets installed as well.
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      07-01-2016, 09:20 PM   #14
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Update :

Module was replaced with a unit from eBay. My oem unit was a ekp2 replaced with a ekp3 unit. No programming needed or anything. But idle psi is still low. Reset fuel trims and such and no help. I will swap out my custom E60 tune for a mhd backend pump gas flash and see if it helps. Might be something in the tune
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      07-02-2016, 05:56 PM   #15
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Another update:

Flashed the mhd jb4 backend pump gas flash. No diffrence. Still low fuel psi.

After about 105miles of driving on the custom tune, I noticed the idle psi went down from 46psi to 38psi at idle and cruising. Something isn't adding up at all.
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      07-02-2016, 06:34 PM   #16
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When I installed my Stg 2 fuel bucket I had a similar problem. My OEM pump kept good pressure at idle, but pressure dropped under boost. The Fuel-it pump had low pressure all the time and the pressure got worse the farther I drove. After a 45 minute drive, I would have pressures in the 30's. It turned out that there was NOTHING wrong with my pump, it was all the low pressure fuel sensor. Replaced that and the pressure was right were it should have been and holds steady.

I guess the tip-off for me was that the car ran fine, even under boost. I was also getting the fuel pump plausibility code and that went away with the new sensor.
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      07-02-2016, 11:46 PM   #17
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Quote:
Originally Posted by Velocity26 View Post
When I installed my Stg 2 fuel bucket I had a similar problem. My OEM pump kept good pressure at idle, but pressure dropped under boost. The Fuel-it pump had low pressure all the time and the pressure got worse the farther I drove. After a 45 minute drive, I would have pressures in the 30's. It turned out that there was NOTHING wrong with my pump, it was all the low pressure fuel sensor. Replaced that and the pressure was right were it should have been and holds steady.

I guess the tip-off for me was that the car ran fine, even under boost. I was also getting the fuel pump plausibility code and that went away with the new sensor.
I replaced my low pressure sensor with a brand new one from bmw, that didn't fix it. On cold starts I'm at 45 or so and by the time it warms up its down to 38ish or so. It's very hard to drive the csr when u are scared of blowing the motor up because there isn't enough fuel
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      07-04-2016, 12:25 PM   #18
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July 4th update :

Picked up a brand new 0 miles deplhi oem pump bucket and got it installed. Jb4 app shows 57 58psi idle on start up right away. Before it was 36 37psi. So I gained about 20psi. Will test voltage and see what it is. Also will throw my stock fuel controller module back on and see if it changes
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      07-05-2016, 07:01 AM   #19
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What was the fuel pressure during a pull?
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      07-05-2016, 09:26 AM   #20
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Quote:
Originally Posted by jtswole View Post
What was the fuel pressure during a pull?
On the aftermarket s2 it was dipping into the 50s sometimes 40s at full throttle, so I really only did 2 pulls as I was scared of further issues. This was on E60.

I switched to map 4 and did a pull and it barely hit 60psi at 8 psi if I rememeber correctly. I know I only floored it 3x since this issue started and since idle psi wasn't all that great it's been preventing me from actually flooring or even driving the car
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      07-06-2016, 02:41 PM   #21
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I would also test fuel pump voltage under load. If pressure is under target, it should be trying to compensate with max system voltage ~13.5vdc.. if voltage is below this then it's a voltage supply problem. Per our conversation in email please let me know the after voltage once you have the pump controller coded to the car.

Thanks Mojo!
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      07-27-2016, 08:35 AM   #22
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Bump this thread


Brand new module installed and coded. Still at 58psi idle with stock pump assembly
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