Walbro question

[Shahek]

Hey guys I need to replace my Walbro 450 but everywhere I look there are two diff part numbers. F90000267 and F90000274. Can’t find enough info to figure out the difference. Any help is much appreciated.

Thanks


Sent from my iPhone using Audizine

[JustManson]

Part number F90000274

This is the updated version with a higher pressure relief valve.

Credit to SeerLah

https://www.audizine.com/forum/showt...one-Walbro-450


IMG_8756.jpg


Sent from my iPhone using Audizine

[Shahek]

Thanks for the speedy answer man I just placed an order for one! really appreciate it!


Sent from my iPhone using Audizine

[christianb5s4]

The high pressure version does make a difference. One thing I recommend you do is hardwire the fuel pump to the battery and cut out the stock fuel pump wiring.

[CELison]

Yes, run power straight from the battery to a relay. Use the factory fuel pump positive wire to trigger the relay. Super easy.

[marka4]

I have hopefully done this but can you confirm the brown and green cable?

[CELison]

Green wire under the back seat.

[Shahek]

Thanks guys!


Sent from my iPhone using Audizine

[Tumbler510]

The high pressure version does make a difference. One thing I recommend you do is hardwire the fuel pump to the battery and cut out the stock fuel pump wiring.

Out of curiosity, why is this preferred over OEM wiring?

[Mocke]

DC current create high Amperage.
That creats heat which melts non properly sized wiring or best case limits the output.
Its a must do. Take it seriously.

[CELison]

DC current create high Amperage.
That creats heat which melts non properly sized wiring or best case limits the output.
Its a must do. Take it seriously.

This. I’ve seen melted tank lids because the pump draws too many amps for the factory wiring to handle.

[Monty23]

Out of curiosity, why is this preferred over OEM wiring?

http://21h1yp1945ct18r0ws184hb2-wpen...re-112-PSI.pdf

First of all, look at this curve from the pump manufacturer Ti Automotive. This is meant to represent a typical pump (also read as: some pumps will draw higher current [amps], some pumps will draw less current).
Current is what we are concerned with here. Higher current means the wiring will heat up hotter than if the wiring was subject to lower current. Wiring is rated for a specific maximum current level over a certain length of wire. The standard wiring is sized for the current that the stock pump draws at boost pressures of 10 psi from those ity bity K03s.

What causes the pump to draw more current? (more heat)
They way our fuel pressure regulators work is that they increase the fuel system pressure 1 psi with every 1 psi of boost pressure. So, if the base fuel pressure is 58 psi (it is with the stock FPR) and you run 20 psi of boost, the pump must make 58 + 20 = 78 psi of fuel pressure + any additional pressure due to the restrictive stock fuel lines. So if you are running 20 psi boost and stock fuel lines which might have a pressure drop of 5 psi (making this number up, the stock fuel lines could be more restrictive than this!!), the pump must spply at least 58 + 20 + 5 = 83 psi of fuel pressure. 83 psi of fuel pressure should be about 18.5 amps of current according to the F90000274 plot.

Can the stock b5 wiring handle 18.5 amps? The diagram below says you should have a 14 gauge wire for 18.5 amp draw assuming the wiring is about 10 ft' long (which I believe it is).
If the wiring is not sized correctly, it could get too hot and start melting... Not something you want near the fuel tank...

Let's also keep in mind that all of our stock wiring is 20 years old, which could cause additional issues if over-stressed.

[christianb5s4]

This. I’ve seen melted tank lids because the pump draws too many amps for the factory wiring to handle.

My stock wiring had definite signs of high heat when all of it was bypassed. I have 10 gauge wiring and zero stock wiring now, with the exception of tapping into the OEM signal wire to trigger the pump.