Today I installed a new Walbro 400lph fuel pump, replacing my Walbro 255lph fuel pump.

This is a 30 minute upgrade if you know what you’re doing. It can take longer if you’re unfamiliar with the S14 fuel system. There are a few things to point out about my Walbro 400 fuel pump that cause me a slight delay:

1. The plugs it came with do not match up to anything. It’s almost like I had a kit for another vehicle. Just clip the plug and crimp or solder the wires to the connector on the S14.
2. The rubber isolator does not match up with the Walbro 400 bottom. You have to kind of cram it into place with the bracket. The 255lph fit like a glove, so this is unfortunate that the over-sized base made the isolator a funky fit.
3. The S14 fuel sock/filter is a tight fit on the 400 but fit perfectly on the 255. You need to use a hammer and a small screwdriver and lightly tap it into place.
4. Pay attention to the + and – symbols on the fuel pump. My 255 was wired backwards. The black was + and the – was red wire. I followed the wire colors instead of the terminal symbols and wired it backwards the first time, which wasted a lot of my time.