There are many good reasons to upgrade the fuel pump in your Z. From just needing to replace your OEM pump because it sat for a long time, or if you're adding a turbo in an NA2T swap, or if you're upgrading to a larger turbo or even want to run E85, upgrading your fuel pump is an important part of making your Z better, and chasing after more power! (Find a good list of pumps here)
This write-up is based off my experience of installing a Walbro 255 pump into my Z, the challenges I faced, and the mods I had to employ to get the pump to work correctly.
This write-up is based off my experience of installing a Walbro 255 pump into my Z, the challenges I faced, and the mods I had to employ to get the pump to work correctly.
Step 1: Removing your tank
Unfortunately for us Z31 enthusiasts, there is no convenient way to remove the fuel pump with the tank still in the car, which means you either have to cut a hole in your Z's trunk or drop the tank. For me, I chose to keep my Z as stock as possible which meant the removal of the fuel tank, which is a fairly involved process. The video linked below is a good visual representation of the following instructions.
The first step in removing the tank is to disconnect the fuel pump and fuel sending unit harness in the trunk of your Z. There are two connectors that run through the circular "lid" located in the floor of the trunk. The rubber grommets which protect these wires in the lid then need to be removed to slip the connectors through the lid when the tank is ready to be dropped.
In order to remove the tank, the rear of the car needs to be jacked up a decent amount as you will need to be able to access the top of the tank once it is lowered so you can remove the fuel hoses from the top of the fuel pump assembly.
Unfortunately for us Z31 enthusiasts, there is no convenient way to remove the fuel pump with the tank still in the car, which means you either have to cut a hole in your Z's trunk or drop the tank. For me, I chose to keep my Z as stock as possible which meant the removal of the fuel tank, which is a fairly involved process. The video linked below is a good visual representation of the following instructions.
The first step in removing the tank is to disconnect the fuel pump and fuel sending unit harness in the trunk of your Z. There are two connectors that run through the circular "lid" located in the floor of the trunk. The rubber grommets which protect these wires in the lid then need to be removed to slip the connectors through the lid when the tank is ready to be dropped.
In order to remove the tank, the rear of the car needs to be jacked up a decent amount as you will need to be able to access the top of the tank once it is lowered so you can remove the fuel hoses from the top of the fuel pump assembly.
Step 2: Upgrading your pump
Once the tank it out of the Z, the fun work begins- Upgrading your fuel pump! There are many choices and considerations when upgrading your pump such as planned injector size and if you want to be able to run E85 fuel or not. A standard upgrade pump is the Walbro 255 which is a 255lph pump which is a massive improvement over the stock pump (70lph or possibly 40? Don't quote me on that but it's a good deal less than the Walbro). The Walbro 255 can be obtained for sub $100 from various outlets such as amazon.com and many other sources. It is a good starter pump if you aren't chasing crazy high horsepower goals as it is small, compact and easy to install in the stock Z31 fuel pump assembly.
Once the tank it out of the Z, the fun work begins- Upgrading your fuel pump! There are many choices and considerations when upgrading your pump such as planned injector size and if you want to be able to run E85 fuel or not. A standard upgrade pump is the Walbro 255 which is a 255lph pump which is a massive improvement over the stock pump (70lph or possibly 40? Don't quote me on that but it's a good deal less than the Walbro). The Walbro 255 can be obtained for sub $100 from various outlets such as amazon.com and many other sources. It is a good starter pump if you aren't chasing crazy high horsepower goals as it is small, compact and easy to install in the stock Z31 fuel pump assembly.
Step 3: Independent fuel pump power source
The most important step in getting your new pump to run correctly is to wire in a new, independent power source for your more powerful pump. There is some speculation if it is really needed, but after running my pump on the ecu power for a few minutes, the pump would no longer receive power after the initial prime from the ECU when trying to start the car. This would result in the car starting and then dying after a few seconds, presumably due to the pressure in the lines being enough to start the car. In my opinion, it is better to be safe than sorry and an independent source guarantees your pump will have all the power it needs to deliver fuel to your engine under all conditions.
The most important step in getting your new pump to run correctly is to wire in a new, independent power source for your more powerful pump. There is some speculation if it is really needed, but after running my pump on the ecu power for a few minutes, the pump would no longer receive power after the initial prime from the ECU when trying to start the car. This would result in the car starting and then dying after a few seconds, presumably due to the pressure in the lines being enough to start the car. In my opinion, it is better to be safe than sorry and an independent source guarantees your pump will have all the power it needs to deliver fuel to your engine under all conditions.