Wiring for Walbro 450

[LightningLou]

So I just bought the Racetronix 10ga wiring kit and I need to install it. How are you guys modding your fuel hats to route the wires through to the pump?

[Corradovolksb]

Most people are using the stock wires from the hat to the pump and running bigger gauge wire to be connector at the hat. The wires from the hat to the pump won't cause that big of a voltage drop unless they are really worn or corroded and I'm sure that would be a very rare case since the wires are submerged in fuel but I guess it could happen.

[LightningLou]

Most people are using the stock wires from the hat to the pump and running bigger gauge wire to be connector at the hat. The wires from the hat to the pump won't cause that big of a voltage drop unless they are really worn or corroded and I'm sure that would be a very rare case since the wires are submerged in fuel but I guess it could happen.

Oh okay cool thanks. I wasn't sure if people were making terminal posts or not on the hat or not instead of splicing into the factory wiring. Which wire is the signal wire to the pump?

[CJ_]

The positive at the cap is the green/yellow I think (Its the largest diameter one), and neg is the larger diameter brownish one (theres two that are really similar color, the other is for the fuel level sender)

And yes, I hardwired my pump to the stock wires where they come out from under the rear seat to keep the wires and relay hidden, and Im getting 13.9 volts to the pump

[Monty23]

Oh okay cool thanks. I wasn't sure if people were making terminal posts or not on the hat or not instead of splicing into the factory wiring. Which wire is the signal wire to the pump?

There are 4 wires:

At the plug to the fuel pump hat connector:
Green/Yellow = fuel pump 12V
Thick Brown = Fuel pump ground
Viloet/Black = level sensor +12V
Thin Brown = level sensor ground

[Corradovolksb]

One more thing to remember is that the power and ground are reversed at the pump so the black is power and the red is ground. At least that's how it's been on the 450s I have installed.

[LightningLou]

There are 4 wires:

At the plug to the fuel pump hat connector:
Green/Yellow = fuel pump 12V
Thick Brown = Fuel pump ground
Viloet/Black = level sensor +12V
Thin Brown = level sensor ground

Okay great thanks! I guess I need to run a wire to the end of this harness because there is a small wire coming out for signal to trigger the included relay. Anyone know which wire on the ecu is fuel pump signal or elsewhere closer to the pump I can tap into?

[f4m0u5]

Okay great thanks! I guess I need to run a wire to the end of this harness because there is a small wire coming out for signal to trigger the included relay. Anyone know which wire on the ecu is fuel pump signal or elsewhere closer to the pump I can tap into?

The signal wire to new solinoid is the green/yellow going to the fuel pump. You need to run a power wire from ur battery to the relay. Then from the relay to the green/yellow wire going into the hat.

[NOTORIOUS VR]

One more thing to remember is that the power and ground are reversed at the pump so the black is power and the red is ground. At least that's how it's been on the 450s I have installed.

It's not reversed at all.

It's just that black is power and Brown is ground (as usual on German cars)

[vavJETTAw36]

It's not reversed at all.

It's just that black is power and Brown is ground (as usual on German cars)

It's technically not reversed. But the brown, after being submerged for so long, appears to be red when it is actually brown. When I see red and black I automatically think red positive black negative. If I see black and white (AC current) I think black hot and white neutral(ground).

I don't know where you've been looking on the Audi but it is mostly red positive and brown or black negative for simple circuits.


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[NOTORIOUS VR]

It's technically not reversed. But the brown, after being submerged for so long, appears to be red when it is actually brown. When I see red and black I automatically think red positive black negative. If I see black and white (AC current) I think black hot and white neutral(ground).

I don't know where you've been looking on the Audi but it is mostly red positive and brown or black negative for simple circuits.


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There are many blacks (and variations of blacks ie. black w/ white or black w/ yellow, etc) which are positive in VAG cars of the B5 and older generations. It is what it is.

Brown is always GND. That it's discolored sure I understand that (I never did look red to me though) and I can understand the confusion for most I made the same mistake initially. That said the OE pump is also marked + and - on the wire terminals

[vavJETTAw36]

There are many blacks (and variations of blacks ie. black w/ white or black w/ yellow, etc) which are positive in VAG cars of the B5 and older generations. It is what it is.

Brown is always GND. That it's discolored sure I understand that (I never did look red to me though) and I can understand the confusion for most I made the same mistake initially. That said the OE pump is also marked + and - on the wire terminals

Lol I made the same mistake. I ended up switching the connectors on inside that connect to the hat. This was even after reading about it months previously. FML


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[CJ_]

This is how I have mine wired under the back seat:
The wires coming off the cap run right under the seat through a grommet, all I did was cut back the black sheathing, and tapped into the wires there. That way the only long wire I had to run was the +12v from the battery (red wire at bottom of picture). Cut the FP wires, use the side coming from the FP relay to power the new relay, then tap your 10ga into the side going to the cap. Everything then just gets tucked away under the seat.

[f4m0u5]

This is how I have mine wired under the back seat:
The wires coming off the cap run right under the seat through a grommet, all I did was cut back the black sheathing, and tapped into the wires there. That way the only long wire I had to run was the +12v from the battery (red wire at bottom of picture). Cut the FP wires, use the side coming from the FP relay to power the new relay, then tap your 10ga into the side going to the cap. Everything then just gets tucked away under the seat.

Finishing up my rewire tomorrow, quick question about the ground.

Do you upgrade the ground to fuel pump also? Or just the power wire coming from battery to relay to fuel pump?

Edit: after zooming in it looks like you did upgrade the ground wire and used original ground to fuel pump as ground to relay?

[julex]

original ground is used to power relay, new ground from connector/pump to seat belt attachment point. MAKE SURE to sand paper chassis to bare metal under the bolt and clean everything up nicely to ensure good ground.

[jimmer009]

So I got my walbro 450 in I'm still running lean. Yes I need a pressure gauge. What do you guys think of this???

I found it on nefmoto

http://foreinnovations.blogspot.hu/2...-for-free.html

[Steve Bassen]

What base fuel pressure are you running? Stock 4 bar and an unmoddded 450 should start bleeding pressure around 22psi.

[jimmer009]

Yea stock 4 bar. Witch means 58 psi at idle. So I need 85 psi cause 58psi + 25psi. I don't mean to thread jack. Just a problem I have been having for almost a month

[julex]

Yea stock 4 bar. Witch means 58 psi at idle. So I need 85 psi cause 58psi + 25psi. I don't mean to thread jack. Just a problem I have been having for almost a month

It doesn't mean 58 at idle. Idle (engine running with no load) is about -20inhg which is 2/3 of 1bar, which is ~10psi. So technically idle fuel pressure should be around (4bar * 14.5psi) - 10psi = 58 -10 = 48psi.

You will have FPR trying to give actual 58psi if you hardwire pump to battery and keep the engine off so that intake manifold pressure = ambient pressure.

However, even on stock wiring you will probably still overwhelm the FPR so actual pressure will be more, especially when idling the engine.

[NOTORIOUS VR]

It doesn't mean 58 at idle. Idle (engine running with no load) is about -20inhg which is 2/3 of 1bar, which is ~10psi. So technically idle fuel pressure should be around (4bar * 14.5psi) - 10psi = 58 -10 = 48psi.

You will have FPR trying to give actual 58psi if you hardwire pump to battery and keep the engine off so that intake manifold pressure = ambient pressure.

However, even on stock wiring you will probably still overwhelm the FPR so actual pressure will be more, especially when idling the engine.

That said, he is right with his calculation that under boost he will be over the stock bleed of the 485.

Also a 485 overwhelms the stock FPR so idle/vac rail pressure is quite a bit higher than it should be.

[GottaBAUDI]

Most people are using the stock wires from the hat to the pump and running bigger gauge wire to be connector at the hat. The wires from the hat to the pump won't cause that big of a voltage drop unless they are really worn or corroded and I'm sure that would be a very rare case since the wires are submerged in fuel but I guess it could happen.

Picture??

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[jaychen]

Picture??

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Did you not see post #13?

[killerkali]

I had the stock walbro in tank connector fail after 2 years on E85

[Der Konig]

Figure I will bump this one to ask and then maybe someone else will find it later. So I understand how to wire this all in and have everything ran, but with the racetronix kit you are given a "redundant ground". Now this makes sense to me since the ground wire for the pump doesnt get upgraded, only the relay section. So are people just tapping the thick brown wire (ground for the pump) and essentially "y-ing" it to the chassis at the seat belt mount to give an additional chassis ground point?

Like in my 5 year old drawing that probably should've been done in crayon? I pm'd OP the question too but figured someone might benefit since this is the first post when you google b5 s4 walbro 450 wiring

https://imgur.com/FJWWDdY

This is the relay kit

https://www.racetronix.biz/product.asp?ic=fpwh-009

Seems like a nice product for the price also by the way

[CELison]

I don't have the kit, but I have a relay for my 450 so same thing. I ran the pump ground to a large bolt in the trunk, and separate wire for the relay ground.

[Der Konig]

I don't have the kit, but I have a relay for my 450 so same thing. I ran the pump ground to a large bolt in the trunk, and separate wire for the relay ground.

Yeah for sure, except the relay ground is tied in at the battery for mine. So the relay has it's own separate ground to the battery. So the redundant ground if I splice it in would just be that...redundant I assume.

[Der Konig]

So I finished this, my wiring diagram is right for future people. I dont think the redundant ground is 100% necessary but sure doesn't hurt. I mounted it to one of the studs underneath the seats.

For racetronix...

Pink goes to green yellow from the chassis and red goes to green yellow from the pump.

Splice the thick brown and add in the redundant ground for safe measure.

For what its worth, pics below. Waiting on my rivnuts to finish up the relay and fuse mounting.

Cheers.



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[Der Konig]

If wanted I can do a diy specifically for the walbro 4501537570111341.jpeg1537570138889.jpeg1537570169717.jpeg

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[julex]

I run it differently. Mine has a short cable from battery + to toggle 30A fuse bolted right next to battery (quality water proof BUSMAN unit with reset, don't use any chinese crap fuse holders for this) , then I run 8AWG to pump location. This next goes to relayed contact on relay and goes out the other side to pump lid and then to pump. The relay is triggered by stock + and - wires from harness - there is practically no load on wires this way - no questions about what ground uses what cable and intuitive wiring. Pump gets separate (-) from a cable bolted to chassis... I think I used the seat belt location making sure it is mega clean etc.

[CELison]

I run it differently. Mine has a short cable from battery + to toggle 30A fuse bolted right next to battery (quality water proof BUSMAN unit with reset, don't use any chinese crap fuse holders for this) , then I run 8AWG to pump location. This next goes to relayed contact on relay and goes out the other side to pump lid and then to pump. The relay is triggered by stock + and - wires from harness - there is practically no load on wires this way - no questions about what ground uses what cable and intuitive wiring. Pump gets separate (-) from a cable bolted to chassis... I think I used the seat belt location making sure it is mega clean etc.

This is how mine is ran. Short cable from bat to a Eaton H type fuse, then back to the relay with 10AWG wire. Then from the relay to the pump. Relay ground and pump ground are separate and bolted to the chasis. Stock wiring is the relay switch.

[Der Konig]

Appreciate the input. Similar to mine, just relay is right next to the battery along with the fuse holder. Fuse within 12" of battery and relay right next to it. The reset able breaker set up is interesting, maybe ill look into that.

Racetronix is quality stuff so not worried about quality. Maybe I am not explaining correctly. The relay ground is separate from the pump ground. I just installed an extra ground along the pump's stock wiring. Just wanted a good ground closer to the pump.

I ended up doing the redundant ground with the supplied wire and grounding it to the chassis. Everything works great.

[julex]

so you run extra wiring to get the original pump wire to the relay next to your battery? - this is what I wanted to avoid... also what kind of relay is this? I hope some good waterproof stuff as there is water in that location - this is another reason why I installed relay right near the pump lid - no water in there ever.

[CELison]

Why not run the relay right by pump? It's extremely easy to tap into the factory wiring there to switch the relay, and you have a ton of ground options for the relay and pump. No need to run anything back up to the front of the car.

[Der Konig]

It is just how the kit is set up, picture is kind of janky for some reason but gives the idea.

https://www.racetronix.biz/product.asp?ic=fpwh-009

The relay and fuse are both at the front at the battery side. You would still have to run the power wire back up to the front, how are you avoiding running wires to the front without using the stock awg wiring? EDIT: I think you are saying no need to run an extra wire for the ignition and just need to run the power.

And yeah, all of this is weather proof.

Went with this kit because searching led me to believe this was a good solution for this set up. I don't really see why it matters if you have the relay mounted under the seat or in the front. I like the idea of just removing the battery shroud to check my fuses and signal wires rather than ripping my rear seats out again.

My only confusion was with the redundant ground, but I guess thats why it is redundant. Didn't seem necessary to me.

6 one way, half a dozen the other. Appreciate the input fellas.

[vavJETTAw36]

It is just how the kit is set up, picture is kind of janky for some reason but gives the idea.

https://www.racetronix.biz/product.asp?ic=fpwh-009

The relay and fuse are both at the front at the battery side. You would still have to run the power wire back up to the front, how are you avoiding running wires to the front without using the stock awg wiring? EDIT: I think you are saying no need to run an extra wire for the ignition and just need to run the power.

And yeah, all of this is weather proof.

Went with this kit because searching led me to believe this was a good solution for this set up. I don't really see why it matters if you have the relay mounted under the seat or in the front. I like the idea of just removing the battery shroud to check my fuses and signal wires rather than ripping my rear seats out again.

My only confusion was with the redundant ground, but I guess thats why it is redundant. Didn't seem necessary to me.

6 one way, half a dozen the other. Appreciate the input fellas.

Just comes down to preference. Nothing wrong with your approach.

I personally went the "under the seat" method for a few reasons:

1) easy junction to the factory fuel pump wiring = less wiring
2) tidier, no relay chilling in that dirty area
3) easier to mount a relay so its not loose
3) no chance of failed seals on a weatherproof item.



again, just preference.

[Der Konig]

All good points, not too worried about the exposure. This is just a track and fun car for me so it isnt driven in anything over light rain. Mounted the relay and fuse with stainless rivnuts, need to straighten them a bit. All turned out well I think. All covered by the rain tray too.

Thanks for your help and input all!
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[Perth_RS4]

Instead of mucking around with relay's, I took this approach. Upgraded the wiring to feed the MSD2351. Now I can adjust how hard the pump works based on manifold pressure. Adjustable output voltage range is 12vdc to 22vdc.
MSD2351 gets the fuel pump run trigger from the existing wiring so it works like one.
Wiring is connected to main Bus under the dash and not the battery.
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[marka4]

Hi there how mutch power are you making on one of these pumps? I have been looking at getting the srm twin pump kit or the brushless kit have a vipec i88 ecu but unsure what one to get. My top hat is damaged sadly, just seeing what's best way to go in New Zealand exchange rate is terrible atm

[Der Konig]

These pumps can support a lot of power, 450lph is a very high flow rate. I have seen people push over 600whp with them on e85.

Walbro 450LPH - TI Automotive TIA450-2 Fuel Pump
Walbro Part Number: F90000274 / 400-0085 Full Install Kit
Type: Universal E85 Intank Fuel Pump
Fuel: FLEX (E85 Ethanol Safe)
Horsepower: 750HP+
Flow Rate: 450LPH

[Der Konig]

Instead of mucking around with relay's, I took this approach. Upgraded the wiring to feed the MSD2351. Now I can adjust how hard the pump works based on manifold pressure. Adjustable output voltage range is 12vdc to 22vdc.
MSD2351 gets the fuel pump run trigger from the existing wiring so it works like one.
Wiring is connected to main Bus under the dash and not the battery.


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That is an interesting configuration, never thought of doing that. Assume you are pushing some serious power to warrant that type of voltage to these pumps.

SPECIFICATIONS 465 lph @ 40 psi and 13.5V (14.1 amps), wonder how it reacts to over that.