Walbro 525 wiring

[sleet142]

@N54rsenal The thought process is that a walbro 525 at full current will blow the fuse for the EKP. If it can pull enough current to blow the fuse, it sure as hell can pull enough current to fry the EKP.

The Walbro 525 can work in place of the stock pump. But if you run too hard you risk the chance of:

1. blowing the fuse and being stuck on the road (unless you replace the fuse with a higher amp fuse)
2. overheating the ekp and having issues similar to what JT had.

That's why I decided to do the rewire, and JT purchased the EOS BPM4.

 

[scrllock]

I have a 2010 E90 335i will running a Walbro 525 itself in the factory bucket work without issues such as frying the Factory EKP?
I already get a shadow code (fuel pump plausibility) with my stock fuel pump at 79K. During every pull its around ~50PSI.
A single Walbro 525 Hellcat Fuel Pump is 700WHP Capable on E85 that's perfect as a single LPFP.
Why does Fuel-it offer a Walbro 525 upgrade option on their stage 2 LPFP if it doesn't work?

Ideally I would buy the EOS BPM4 EKP replacement for X2 525's and avoid using X2 450's+Hobbs switch which would clean things up, but im only on stock turbos it would be a waste.

For stock turbos even a single 450 is more than enough, no? Can't speak to fuel-it's reasoning before, but now that the BPM4 is available, it seems to me the single 525 is a viable option, with clean wiring.

BTW, got a source for 700 whp on e85 with a single 525? Been looking for solid info before deciding between the 2x450 or a single 525.

 

[N54rsenal]

I meant to say 700HP on E85 which would mean 600whp but look at this they say the TI Automotive Walbro 525 can but I think its a typo - https://www.driftmotion.com/Walbro-F90000285-525LPH-E85-Hellcat-Pump-p/dm3592.htm

I don't know if I should go bucketless, I can buy a DW400 and not worry about being bucketless or needing to upgrade my EKP since im on stock turbos.

 

[sleet142]

I meant to say 700HP on E85 which would mean 600whp but look at this they say the TI Automotive Walbro 525 can but I think its a typo - https://www.driftmotion.com/Walbro-F90000285-525LPH-E85-Hellcat-Pump-p/dm3592.htm

I don't know if I should go bucketless, I can buy a DW400 and not worry about being bucketless or needing to upgrade my EKP since im on stock turbos.

I went bucketless with a hydramat. There's testing behind going bucketless for more flow and the hydramat has a larger surface area inside the fuel tank over the stock pickup sock. But in your situation you can go either way. With stock turbos, you shouldn't be running out of fuel anytime soon unless you decide to go crazy with your e85 mixes. A bucket or bucketless install will take an equal amount of time to install. Just make sure you have all the hardware for the bucketless install.

Having the Walbro 525 as an option is making you think too much. If you're concerned with hurting the ekp, just know that the Walbro 450 is a 450lph pump and the Walbro 525 is a 470lph pump (at the pressures our cars require). The easy choice is to forget that the Walbro 525 exists and grab a 450 or the DW400. Many people have good results with the Walbro 450 on all turbo specifications for our cars. (upgraded twin or single)

 

[N54rsenal]

I got the Precision Raceworks Stage3+ Modular LPFP with x2 Walbro 450's. So down the line if I plan on going single turbo I will get the EOS BPM4 LPFP Controller EKP replacement for x2 pumps which will have the harness to run the 2nd Walbro 450. The 2nd 450 won't be doing anything until its needed via connecting the positive and negative terminals to power it, no need to remove entire fuel pump again and do the stage 3+ upgrade later when I can just do it once also no hobbs switch harness will be needed. I didn't want to piece together a single pump or go bucketless but I did come across the hydramat idea which got my attention but they are expensive, I liked the Vader Solutions bucketless bracket which looks like it can run a DW400 and or two Walbros.

That's what I thought about with the 525 if I can't even run 1 why bother. What could be wrong with using x2 450's, they can support 900whp which is plenty for a stock engine capable of 850whp. The 450's could easily be upgraged to 525's if going overkill. I plan on getting a Pro Tune for E50 soon but will have to play around with ethanol mixtures so I got a Fuel-It Pro Series Ethanol Test Kit and will check what I get from the E85 pump near me as it ranges from 51%-83% ethanol here in Chicago.

 

[fmorelli]

[...snip...] just know that the Walbro 450 is a 450lph pump and the Walbro 525 is a 470lph pump (at the pressures our cars require). The easy choice is to forget that the Walbro 525 exists and grab a 450 or the DW400.

I meant to add to this, when I read it, but just hadn't gotten around to it. Static lph measurement (measured at a fix point) is crude and rather incomplete for comparison sake. But to @sleet142 's point, the 525 is also called the 470 to more accurately represent its single metric flow rate. But there is much more to this. For anyone interested, I'd suggest this article for some reading on understanding the LPFP Walbro pumps, factors, etc. Fuel type, flow requirements at PSI levels, and headroom on the pump (yeah I know N54 people love running everything to max capacity, having it blow up, then complain how the cars are not reliable. Or ditto on worn parts, but I digress) ... are all factors for consideration. Anyway the article is a 3-5 minute read and fairly concise.

Unfortunately it is probably even more complicated. Because the N54 folks generally don't have an upgrade path for the HPFP, they try to solve the fuel availability issue by providing more pressure from the lift pump side - as I understand it, the idea here is that it eases the job on the HPFP. Honestly I don't understand how that works, given the rather low PSI availability of an LPFP versus where the HPFP needs to go - two orders of magnitude greater PSI. I'm sure there is a simple answer on this; I just don't understand it - maybe someone can explain that to me.

As an aside, given the Z4 implementation of the N54 (along with some other race applications) which do not run an LPFP sensor, do not modulate the LPFP based on pressure ... and some tuners seem to consider the Z4 as an out-of-the-box "stage 2" LPFP (versus say 335i implementation) ... I wonder why the Z4 even needs an EKPS (it does have it). But that's a separate discussion I suppose.

Filippo

 

[GreyNBlueE92]

On the topic of fuel pumps, I had the thought of putting a soft start circuit on the pump(s) controlled by a hobbs to avoid a sudden spike in fuel pressure.

Would this be a bad idea/is this possible?

 

[sleet142]

At the moment my HPFP is suffering at 21 psi with no supplemental fuel injection (To add to fmorelli's point). That's with 10 gallons of ethanol from an E50 minimum pump (no I didn't test the fuel) and a target of 12.2 afr. A lpfp upgrade helps with a lot of issues in the fueling department, but it is not the end-all be-all fix.

 

[Lurcher]

Shoving higher pressure through a small "interface" just will get you a cooler solvent (i.e.A/C), there is still a volume/capacity issue. Seems that the ~450+ hp constraint is not the delivery (PSI) but the tubing. With bigger hoses, drilled out fuel rail, bigger injectors, pressurized fuel reservoir, etc. as options - there has to be some other location that is the physical constraint to the flow issue - right? At some point more PSI can't solve a volume issue.

Also wondering if this could cause the "surging" issues many out here have (I"m dealing with now)....

 

[jts1981]

At the moment my HPFP is suffering at 21 psi with no supplemental fuel injection (To add to fmorelli's point).

I agree. We're covered on the lpfp side but the hpfp needs a real upgrade, probably need larger injectors too if your shooting for top power. I'm crossing my fingers for the dual hpfp solution that is dme controlled. GAME CHANGER my friend...

 

[fmorelli]

Michael, yep want to run bigger lines, especially with ethanol which takes a significantly more volume. Both my and Jacob's Z4's are plugged with bigger line from Fuel-It. And Jacob is right ... dual HPFP DME controlled for a native solution. Here's to patience and hoping 2019 is the native DI year for 600whp capability.

Filippo

 

[sleet142]

I've had to lean the afr out (12.651) and lower the boost to 20psi for the rail to stay consistent.

 

[Eracer76]

This was my solution to getting more fuel then the Z4 fuel pump could provide... lol I basically removed the whole stock fuel system, tank and all, and replaced it with a fuel cell and a FueLab pump thats capable of 800+ hp on 100% pump E85. I just used the factory pump wiring to trigger a mechanical relay that powers the new pump with heavy gauge wire from the battery. Yes I get fuel pump codes that pops up, but it hasn't effected anything with drivability. I know my pump runs 100% all the time, but I'm also running a FueLab FPR with a fuel return line to the fuel cell, so that isn't an issue.

Now that I see this talk about a new aftermarket EKP, I wonder if really works on the Z4, since the Z4 doesn't have a LPFS? Maybe the stock EKP uses current draw to determine how hard the pump is working? What I'm really wondering is, has anyone even verified that the Z4 doesn't run the pump 100% of the time? The system is completely different then a 335i, and it appears to use a FPR thats built into the fuel hat, that returns fuel back into the bucket/tank. Does the 335i system have a FPR that does this?

I'm curious about all this again, because I'll be changing turbo systems again, and I'm thinking about putting my stock fuel tank back in the car instead of using the fuel cell.

 

[fmorelli]

Now that I see this talk about a new aftermarket EKP, I wonder if really works on the Z4, since the Z4 doesn't have a LPFS? Maybe the stock EKP uses current draw to determine how hard the pump is working? What I'm really wondering is, has anyone even verified that the Z4 doesn't run the pump 100% of the time? The system is completely different then a 335i, and it appears to use a FPR thats built into the fuel hat, that returns fuel back into the bucket/tank. Does the 335i system have a FPR that does this?

I'm curious about all this again, because I'll be changing turbo systems again, and I'm thinking about putting my stock fuel tank back in the car instead of using the fuel cell.

@jts1981 is running the EOS EKP on his Z4 with VTT GC Lites. He can chime in. Also tagging @NoQuarter and @BQTuning around the LPFP behavior on the Z4.

Filippo

 

[scrllock]

LPFS

I'm not sure exactly what the bpm4 can offer, but mine had a checkbox on the box it came in for a LPFS, which wasn't something I was aware they took into account.

 

[NoQuarter]

@jts1981 is running the EOS EKP on his Z4 with VTT GC Lites. He can chime in. Also tagging @NoQuarter and @BQTuning around the LPFP behavior on the Z4.

Filippo

Right on... Just getting to the pump to scope it out takes some effort I have been putting off.

 

[Eracer76]

I'm not sure exactly what the bpm4 can offer, but mine had a checkbox on the box it came in for a LPFS, which wasn't something I was aware they took into account.

View attachment 27828

Yes, that is interesting. I wonder how the BPM4 knows how much fuel is needed and adjusts the fuel pump and or adds in the secondary pump accordingly if there is no LPFS... hmmm.

 

[EOSpeed]

Yes, that is interesting. I wonder how the BPM4 knows how much fuel is needed and adjusts the fuel pump and or adds in the secondary pump accordingly if there is no LPFS... hmmm.

The BPM4 works exactly like the factory unit does. In the PT-CAN signal, the DME tells the unit how much to modulate the pump in the system. So we are reading duty cycle requirements from the DME and translating it for the pumps. The internals of the BPM4 are built to withstand much higher amperages than the stock EKP unit can. So for cars like the Z4 and N55 engines where there is no LPFS, we load a different control sequence on the modules, so it can talk to the DME properly.

 

[Eracer76]

The BPM4 works exactly like the factory unit does. In the PT-CAN signal, the DME tells the unit how much to modulate the pump in the system. So we are reading duty cycle requirements from the DME and translating it for the pumps. The internals of the BPM4 are built to withstand much higher amperages than the stock EKP unit can. So for cars like the Z4 and N55 engines where there is no LPFS, we load a different control sequence on the modules, so it can talk to the DME properly.

I'm bringing this subject back up again, as I feel there are still a bunch of unknowns about the fuel system...

Thanks for the info @EOSpeed ... I'm considering reinstalling my factory fuel tank and buying the BPM4 to run my single FueLab pump in the tank... But, I'm still wondering how the DME knows how much to modulate the LPFP without a sensor? Is the DME just blindly modulating the pump based off of other sensors like the HPFP, engine load, RPM and so on? Or... is it even really modulating the pump at all... and instead just running it 100% and then dumping the excess fuel back into the system via the FPR thats built into the fuel hat on the tank?

Does anyone know if the 335i system has a FPR in the tank that also does this?
If the 335i doesn't have a FPR in the tank, then maybe that explains why the 335i system needs a LPFS to modulate the pump and the Z4 doesn't?