MR2 Turbo Center-Feed Fuel Rail: The Fuel Rail

MR2 Center-Feed Fuel Rail Installation: The Fuel Rail

Overview	Fuel Pump	Fuel Pressure Regulator	Parts List

The first step in modifying the fuel rail is removing it from the engine. You must remove the throttle body to access the fuel rail. Remove the turbo hose between the intercooler and the throttle body inlet. Detach the throttle cable linkage from the linkage bracket on the throttle body. Remove the throttle body inlet being careful not to drop the gasket between it and the throttle body. Unbolt the throttle body stay from the valve cover and the throttle body. Unclamp the water hoses from the idle speed control valve on the underside of the throttle body and plug these hoses to prevent coolant from leaking and air from entering the cooling system. Unplug the idle air hose from the idle speed control valve. Unplug the EGR and evaporative hoses from the top of the throttle body. Unbolt the bracket holding the EGR vacuum modulator and VSV to the manifold and label and unplug the engine harness connector to the VSV and the hoses going to these components so that you can later reattach them properly. Disconnect the idle speed control connector and the throttle position sensor connectors on the engine harness. Unbolt the throttle body from the intake manifold.

Disconnect the battery before continuing. Unscrew the fuel feed line from the top of the fuel filter located forward and left of the transmission beneath the fuel filler pipe. Catch the fuel that will pour out of the line in a container. Unscrew the fuel feed line from the #1 cylinder side of the fuel rail and from the metal fuel rail cover. Unbolt the bracket that holds the fuel line to the water outlet pipe on the back of the engine. Pull the entire fuel line out of the engine bay. Take one of the Earls 991945 12mm X 1.25 to -6AN adapters, apply Teflon tape to the threads and screw it into the hole on top of the fuel filter. Do not over tighten it.

If the cold start injector is still connected to the system, disconnect the hoses from the fuel rail and the cold start injector at this time. There might be a little fuel in this line that should be carefully captured. If you are going to leave the cold start injector in place to cover the hole that it mounts over in the intake manifold, remove the fuel line from the injector and use an appropriate sized bolt with a gasket or Teflon tape to seal the injector so that it does not leak boost or vacuum. The cold injector location is a perfect place to install a MAT sensor for use with an EMS as described in the TEC³ manifold sensors installation section.

Disconnect the four injector connectors from the engine harness and take off the bolts that hold the engine harness conduit against the intake manifold to allow a little extra room to pull the fuel rail out. Disconnect the vacuum tube between the intake manifold and the metal pipe leading to the fuel pressure regulator. Disconnect the fuel return line from the fuel pressure regulator carefully catching the fuel in the line in a container. Disconnect the other end of the return line from the return tube near the front firewall heat shields. Unbolt the fuel rail from the head and carefully retrieve the three spacers between the head and the fuel rail. Carefully extract the fuel rail being careful not to drop any of the rubber gaskets attached to the fuel injector nozzles.

Before machining the fuel rail, you will need to remove the fuel injectors to prevent metal particles from entering and damaging the injectors. Remove the plate that clamps the injectors to the fuel rail. There is an o-ring on the top of each injector protecting it from the metal plate just removed. Take these off and examine them carefully. If they appear worn or dried out, order a new set from the dealer. Unscrew the stock fuel pressure regulator. Take the rubber gaskets off the end of each injector nozzle and examine them carefully. If they appear worn or dried out, order a new set. The injectors are pressed into the fuel rail with a little pressure but they can be easily removed with an appropriately-sized socket placed over the end nozzle to push against the injector without damaging the delicate nozzle end. Once you do this, you can carefully press the socket downward onto a table or floor while holding onto the fuel rail firmly. Each fuel injector should come out easily with a little pop. There are two o-rings on each injector. Inspect them carefully and order new ones if they are needed. This may be a good time to send your injectors to RC Engineering for cleaning and balancing if you will be reusing them.

Clean the fuel rail with brake cleaner or some other suitable solvent. You will need to place the rail carefully in a vice with the middle post that the cold start injector line plugs into exposed. Use a 27/64" drill bit to carefully bore the middle post all the way down to the middle of the rail. There is not a lot of extra material to work with, so go slowly and carefully. Then, using a 12mm X 1.25 tap, tap the post to accept an Earl 991945 adapter. When this is done, wash the fuel rail thoroughly to remove all metal shavings and dry it.

Take the new fuel injectors and put a new set of o-rings on them if they are not already on. Wet the o-rings with a little lubricant or gasoline and insert them into the fuel rail with the connector pointing in the same direction that the middle post points. Use a properly-sized socket to help you press the injectors into the fuel rail. The socket should place the pressure on the body of the injector and not on the delicate metal tip on the back of the injector. Press each injector into the fuel rail. Place the top o-ring on the top of each injector and then bolt the holding plate back onto the fuel rail. Take three of the Earls 991945 12mm X 1.25 to -6AN adapters, apply Teflon tape to the threads and screw then onto the three fuel holes in the fuel rail. Do not over tighten the middle one--it is both unnecessary with Teflon tape and a crush washer and dangerous since there is not much extra material there.

Place the rubber gaskets on the nozzle of each injector. Put the spacers that go between the fuel rail and the cylinder head back into their holes. These spacers are asymmetrical and the shorter side goes towards the cylinder head. Line up the fuel rail on the spacers and get the bolts that hold it to the cylinder head started by hand. It takes a little patience to get everything to line up perfectly, but it will happen. Once all the bolts are hand-tight, torque them to 14 ft-lbs. Reconnect the vacuum hose from the manifold to the tube on the fuel rail. Plug the fuel injector connectors on the engine harness into their respective fuel injectors. Bolt the engine harness conduit back in place against the intake manifold.

Measure the distance between the center tap of the fuel line and the top of the fuel filter along the best route for the fuel line and build a new -6AN fuel line using high quality -6AN hose ends and stainless steel fuel line of the proper length. Use an Earls 309106 90 degree hose end on the fuel rail side of the fuel line to allow the fuel line to exit out the #4 cylinder side of the engine without improperly kinking the fuel line. Apply Teflon tape to the threads of the adaptors and avoid over tightening the hose ends.

Do not install the throttle body back in place until you finish installing the fuel pressure regulator and the fuel lines as described in the fuel pressure regulator section.