How bad is this for the FPR?

KClemente

Sergeant
Nov 26, 2019
284
147
0
Ride
E90 335i
Like the title says, how bad is it for the fuel pressure regulator to have my secondary pump running at 100% current and the primary pump running through the EKP?

Obviously the fpr will be working in overtime but i'm just interested in longevity and whether or not someone here has done it before. My hobbs switch and check valve is still in the mail and wont arrive for a couple days.

Primary pump is a walbro 450 w/o the checkvalve, and the secondary pump is an E60 535 Bosch unit which happens to flow very similar to the 450.

Low pressure fuel pump values are steady 68-70 at idle, and about 63 at 24 psi with a Helix overdrive.

Reason why the bosch pump is running all the time is because it doesn't have a checkvalve built in and I lose a ton of pressure if that pump is off.
 

martymil

Major General
Sep 6, 2017
3,331
1,906
0
Down Under
Ride
S65 1m
if your running an external reg not a problem, if running the factory unit it wont take long for it to fail as it was designed more of a safety than controlling the fuel pressure.

In the factory system the pressure never exceeds the factory reg and the fuel pressure is controlled by the ekp.
 

KClemente

Sergeant
Nov 26, 2019
284
147
0
Ride
E90 335i
if your running an external reg not a problem, if running the factory unit it wont take long for it to fail as it was designed more of a safety than controlling the fuel pressure.

In the factory system the pressure never exceeds the factory reg and the fuel pressure is controlled by the ekp.
Thanks for the input. I was thinking of lowering the lpfp base pwm down lower in the low fuel request breakpoints. I’m sure with this second pump running full speed, the PI is pegging at max negative
 

doublespaces

Administrator
Oct 18, 2016
9,303
4,331
0
AZ
Ride
2009 E93 335i
What is the factory regulator set to and how many reports of failure have we seen?
 

martymil

Major General
Sep 6, 2017
3,331
1,906
0
Down Under
Ride
S65 1m
pretty sure its set to 75psi or there about.

We pull out the factory fpr and block it off with every dual lpfp pump setup as seen them fail quite quickly if we didn't.