[ab987]

Hey all. Just installed a walbro 535 to replace my dying stock LPFP (I don't want to talk about how that went).
Two things I noticed:

1. There must be some sort of check valve in the FPR or something, because pressure doesn't fall hardly at all when the car is shut off despite the 535 not having a check valve. Is this accurate? This essentially makes the 450 irrelevant as the internal check valve is just an unnecessary restriction.

2. Fuel pressure is interesting right now. My first drive, it stayed at 86psi constantly (which my stock one did only when doing spirited driving), and finally dropped to the normal 73psi towards the end of the drive after 10 minutes or so. The second drive, it started at 73psi, jumped to 90psi, and held 90psi steady through a pull (spiking to 98psi!). This seems very abnormal. What is it doing? I have never in my life seen 90psi and want to make sure this isn't gonna near the capacity of the low pressure system. Log: https://datazap.me/u/ab987/walbro-53...og=0&data=3-21

Thanks for the enlightenment, lots of unexpected results here.

[BSM n54iS]

Not sure bout 1 but for 2 you might be starting to overheat the ekpm..? The 525 draws more amps than the 450 so cooling the ekpm/3 is recommended from what I know

[ab987]

Originally Posted by BdSM n54iS

Not sure bout 1 but for 2 you might be starting to overheat the ekpm..? The 525 draws more amps than the 450 so cooling the ekpm/3 is recommended from what I know

The 535 is essentially a 450 without a check valve and as such actually draws similar if not less current than the 450. I do have heat sinks and a fan for the EPKM and plan on it.

[NoGuru]

535 draws 1 more amp then the 450 and yeah, no check valve but I have been running mine as my primary and a 450 as secondary no problem for a while.
I think that pressure should start to normalize after a few more drives.

[ab987]

Originally Posted by NoGuru

535 draws 1 more amp then the 450 and yeah, no check valve but I have been running mine as my primary and a 450 as secondary no problem for a while.
I think that pressure should start to normalize after a few more drives.

Sounds good. It's so dead on 90psi when I start to do spirited driving that I think my old pump was targeting 90 but couldn't hit it, and this one can no problem.

[iqraceworks]

With my Walbro 450....I get those same pressure fluctuations also. Sometimes cruising around it's at 72psi....but if I get on the gas hard it will jump up to around 85psi and stay there. Other times it's 85psi as soon as I fire up the car. I'm sure it has something to do with the fact that the amp draw and output isn't the same as the oem pump....so the "logic" the DME uses to control the EKP is just a little off.

Either way....I've never noticed any real issues... I wouldn't worry about. Like others have said... overheating the EKP would worry me more than the pressure fluctuations.

[ab987]

Originally Posted by iqraceworks

With my Walbro 450....I get those same pressure fluctuations also. Sometimes cruising around it's at 72psi....but if I get on the gas hard it will jump up to around 85psi and stay there. Other times it's 85psi as soon as I fire up the car. I'm sure it has something to do with the fact that the amp draw and output isn't the same as the oem pump....so the "logic" the DME uses to control the EKP is just a little off.

Either way....I've never noticed any real issues... I wouldn't worry about. Like others have said... overheating the EKP would worry me more than the pressure fluctuations.

Agreed. I'll be putting some cooling on it before I go on any extended drive or run ethanol or anything

[NoGuru]

Originally Posted by ab987

Agreed. I'll be putting some cooling on it before I go on any extended drive or run ethanol or anything

I ran active cooling on my EKPM3 and the 535 and 450 off it.

[ab987]

Originally Posted by NoGuru

I ran active cooling on my EKPM3 and the 535 and 450 off it.

Damn, not bad. I have a single 535 and I believe EKPM2. The laziness in me wants to wait for it to overheat... but that's definitely not the move. I read somewhere to get 5v fans so I got some, but now I'm seeing a bunch of people saying you need 12v fans. Which did you use?

[C.Pop]

450 is the wrong nomenclature; it's common but not accurate. Kinda generic and shouldn't be used.

F90000268
F90000274 -268 & 274 are the same pumps, but the 274 uses a higher pressure relief valve.
F90000285 is the hellcat pump, outflows a 274 by ~10-15% or so, but draws too much current to be used by most EKP's. Skip for primary.
F90000295 is the same as the hellcat pump but without the check valve. It outflows a 274 by about 30%, and draws less current (less restriction w/out the chk vlv) so it's usually tolerated by the EKP. Great single pump upgrade but the lack of chk vlv means it *MAY* result in longer startups on some setups, and it unsuitable for use as a secondary pump in systems that sequentially run multiple LPFP's (most on the market that aren't using an aftermarket pump controller).

[NoGuru]

Lots of good info at S p o o l street about this. https://*********************/thread...for-lpfp.6628/

Yes, 12v is what you should use.
I 3D printed just a flat rectangle and mounted to to the EKP, and added a blower fan + heatsinks. It should be in that thread.

[ab987]

Originally Posted by C.Pop

450 is the wrong nomenclature; it's common but not accurate. Kinda generic and shouldn't be used.

F90000268
F90000274 -268 & 274 are the same pumps, but the 274 uses a higher pressure relief valve.
F90000285 is the hellcat pump, outflows a 274 by ~10-15% or so, but draws too much current to be used by most EKP's. Skip for primary.
F90000295 is the same as the hellcat pump but without the check valve. It outflows a 274 by about 30%, and draws less current (less restriction w/out the chk vlv) so it's usually tolerated by the EKP. Great single pump upgrade but the lack of chk vlv means it *MAY* result in longer startups on some setups, and it unsuitable for use as a secondary pump in systems that sequentially run multiple LPFP's (most on the market that aren't using an aftermarket pump controller).

My confusion comes from the fact that pressure does not drop after shutoff, so there's a check valve somewhere. I see how there could be an issue when running dual pumps, or at least the 535 as a secondary.

[ab987]

Originally Posted by NoGuru

Lots of good info at S p o o l street about this. https://*********************/thread...for-lpfp.6628/

Yes, 12v is what you should use.
I 3D printed just a flat rectangle and mounted to to the EKP, and added a blower fan + heatsinks. It should be in that thread.

Cool. Do you happen to have the schematic or measurements so I don't have to take the controller out twice? Ill see if I can find my old laptop 12v blower that was making a little bit of noise, I think it would be perfectly suited for this task.

[NoGuru]

Originally Posted by ab987

Cool. Do you happen to have the schematic or measurements so I don't have to take the controller out twice? Ill see if I can find my old laptop 12v blower that was making a little bit of noise, I think it would be perfectly suited for this task.

No, but I have some EKP's laying around at home, I will try and take some measurement's if I can find time and remember.

[ab987]

Originally Posted by NoGuru

No, but I have some EKP's laying around at home, I will try and take some measurement's if I can find time and remember.

Cool, thanks

[C.Pop]

Originally Posted by ab987

My confusion comes from the fact that pressure does not drop after shutoff, so there's a check valve somewhere. I see how there could be an issue when running dual pumps, or at least the 535 as a secondary.

Filter/FPR does not have a check valve, probably just not losing suction.

[ab987]

Originally Posted by C.Pop

Filter/FPR does not have a check valve, probably just not losing suction.

Suction wouldn't compress the fluid, so there would certainly still be fuel in the lines but it would lose its pressure and bleed back through the pump if there was no check valve anywhere

[C.Pop]

Fuel is incompressible. HPFP has check valves, LPFP system does not (outside of the pump). Even check valves bleed off some pressure over time. Nothing unusual here, you just aren't losing suction through the system.

[Torgus]

Originally Posted by C.Pop

450 is the wrong nomenclature; it's common but not accurate. Kinda generic and shouldn't be used.

F90000268
F90000274 -268 & 274 are the same pumps, but the 274 uses a higher pressure relief valve.
F90000285 is the hellcat pump, outflows a 274 by ~10-15% or so, but draws too much current to be used by most EKP's. Skip for primary.
F90000295 is the same as the hellcat pump but without the check valve. It outflows a 274 by about 30%, and draws less current (less restriction w/out the chk vlv) so it's usually tolerated by the EKP. Great single pump upgrade but the lack of chk vlv means it *MAY* result in longer startups on some setups, and it unsuitable for use as a secondary pump in systems that sequentially run multiple LPFP's (most on the market that aren't using an aftermarket pump controller).

Well said.

I have a 285 and 295 in my bucket. Fuel for days. I use BPM4 no EKP.

[turbohugh]

Did you reset your fuel adaptations ?
You may also want to recode your EKP to the latest factory specs using NCSExpert. If you get the latest datum files there are revisions to the coding of the EKP .
If you can get your hands in INST-P you may be able to apply updates to your modules as well.

[ab987]

Originally Posted by turbohugh

Did you reset your fuel adaptations ?
You may also want to recode your EKP to the latest factory specs using NCSExpert. If you get the latest datum files there are revisions to the coding of the EKP .
If you can get your hands in INST-P you may be able to apply updates to your modules as well.

It has adapted over a few weeks, it's now idling at 73 as usual and ramps up to 86 when WOT, so I think it was an adaptation thing. I am curious to update it however, I'll look into that. Thanks

[theobjectivist]

Hey OP - hows the 535 (fxx295) pump holding up? Is it still starting without issue?

Is your EKP giving you any problems?