How-to Rebuild Fuel Injectors

Do your fuel injectors need a refresh? Here’s how to rebuild them.

First, you need to buy a rebuild kit. This will include the filters, o-rings, pintle caps, and spacers required to rebuild your injectors. I bought my kit on eBay. If you just want to replace the o-rings, you can buy a “seal kit” instead, like this one.

Next, you need to gain access to your fuel rail, pop off any retaining clips if you have them, and then remove the fuel injectors themselves.

BMW M50 Fuel Injectors & Rebuild Kit

Now mount a wood screw (included in my rebuild kit) that is just large enough to fit inside the injector opening on a vice. Fuel injectors have small, integrated filters inside of them that can clog over time. We will be replacing these filters.

Wood Screw

Carefully thread the injector onto the screw until a few threads bite in, then pull the injector away from the wood screw until the filter comes out. This might be difficult.


Fuel injector threaded onto wood screw

If you are successful, you should see this:


Removed fuel injector filter

Repeat for all your fuel injectors, in my case 6. At this point, you can optionally clean your fuel injectors using fuel injector cleaner. I may cover this at a later date, but I elected not to clean my injectors this time around. Cleaning is a more complicated process – some people have even built elaborate cleaning rigs to pump fuel injector cleaner through the injectors automatically!

Now *carefully* remove the pintle caps and also remove the o-rings. Do not simply yank the pintle caps off with pliers as it is possible to damage them.

Pintle cap, o-ring, and spacer removed

Pintle cap, o-ring, and spacer removed

And then remove the o-ring from the other end.

O-ring removed

O-ring removed

Installing the rebuild kit is simple. Start by installing the new filters. They simply press into place – use a tack hammer to lightly tap them in until flush. Then install the top o-ring by rolling it onto the injector. Finish up by installing the spacer (if needed), o-ring, and pintle cap on the bottom of the injectors. The pintle caps easily snap into place and hold the spacer & o-ring on.

Rebuilt injectors

Rebuilt injectors

Finally, reinstall them on your car!

Newly installed fuel injectors

Newly installed fuel injectors

Happy motoring!