Replacing Fuel Filter In 3000Gt: Step-By-Step Guide

Changing the fuel filter on a Mitsubishi 3000GT is a complex task that requires a range of tools and a good understanding of mechanics. The fuel filter should be replaced every 30,000-60,000 miles, or more often if low-quality fuel is used. The process involves disconnecting the fuel pump, removing the battery, and working in a tight space with little room for error. It is important to relieve fuel line pressure before beginning and to be aware that fuel and its vapours are toxic and flammable.

Disconnect the fuel pump wiring harness

Disconnecting the fuel pump wiring harness is an important step in changing the fuel filter on a Mitsubishi 3000GT. Here is a detailed, step-by-step guide on how to do this:

First, locate the fuel pump in the trunk of the car. It is usually under the passenger side tray and carpet. Once you have found it, the next step is to disconnect the wiring harness. To do this, simply squeeze the tab and pull it off. This will disconnect the power to the fuel pump.

Now, try to start the car. The engine should not start since the fuel pump is no longer connected. If the car hasn't been started in a while, it may not turn over at all. In this case, just crank it with the starter for about 10 seconds.

After disconnecting the wiring harness and testing that the engine does not start, it is important to remember to reconnect the fuel pump wiring harness before moving on. You should feel a click when it is securely attached.

By disconnecting and reconnecting the fuel pump wiring harness, you can safely bleed out the fuel in the injectors, rails, and feed lines. This will ensure that there is little to no pressure in the lines when you start working on them, making it much safer to disconnect the high-pressure fittings and change the fuel filter.

Remove the battery and washer tank

To remove the battery and washer tank from your Mitsubishi 3000GT, you will first need to disconnect the battery terminal connections. Disconnect the negative terminal first, followed by the positive terminal. Be sure to have any security codes that might be needed when the battery is disconnected.

Next, you will need to remove the battery tie-down bar. Use a 10mm wrench or socket to completely remove the bar so that the battery can be lifted out of the car and placed in a safe location.

Now, it's time to remove the battery tray and washer fluid reservoir. There are four 12mm bolts at the corners of the battery tray that need to be removed. You can leave the two more central bolts attached, as they secure the washer fluid reservoir to the battery tray. Be cautious not to scratch the paint on your fender when moving the assembly.

At this stage, you have the option to remove the battery tray bracket for some extra room. There are two 12mm bolts along the bottom that can be removed if desired.

Remove the lower fuel pipe connection

To remove the lower fuel pipe connection, you will need to have already disconnected the fuel pump and removed the battery, battery tray, and washer fluid reservoir. You will also need to have the necessary tools to hand, including a 14mm flare-nut wrench, a 19mm wrench, and safety goggles. Place some shop towels under the filter to catch any gasoline that sprays or leaks out.

Now, to the fuel pipe connection. The service manual says to remove the "U" shaped pipe that turns the fuel line around when it leaves the filter and heads back toward the main fuel line. However, one user found this difficult and instead removed the bottom bolt on the fuel filter, being careful not to lose the gaskets. Another user recommends using a flare nut wrench on the fitting on the "U-pipe" to get it off.

Now, to the fun part! You will need two wrenches (19mm or 3/4") to remove the bolt. Use the closed end on the bolt and grab the neck of the fuel filter with the open end of the other wrench. There's no room for a breaker bar in there, so make sure you're strong enough to break the bolt free. You will probably bleed after this step... and don't lose those two metal gaskets that go around the fuel connection!

Remove the upper fuel pipe connection

To remove the upper fuel pipe connection on a Mitsubishi 3000GT, you will need a 19mm wrench and a 14mm flare-nut wrench (a 14mm open-end wrench will work but you risk rounding the edges of the nut). Place a rag under the hose to catch any gasoline that remains in the rails, pipes, and hose. This gasoline should not be under pressure, but as a precaution, wear safety glasses to protect your eyes when removing the hose.

Using pliers, loosen the clamp and slide it off the hose and onto the pipe behind the fuel filter. Then, with the pliers, gently twist the hose and pull it off the metal pipe.

Now, to remove the line on top of the fuel filter, use a 19mm (or 3/4") wrench below the banjo bolt to hold the filter steady, and loosen the banjo bolt using a 19mm (or 3/4") socket and wrench. If the bolt is frozen or rusted to the filter, you can use a breaker bar to break the bolt free. Alternatively, you could spray the connection with penetrating oil first. After the bolt is loose, remove it so as not to drop the two crush washers that are on either side of the supply line.

You should now be able to remove the upper fuel pipe connection. Remember those gaskets and crush washers!

Remove the fuel filter

To remove the fuel filter, you will need to first relieve the fuel line pressure. Remove the carpet and particle board floor in the rear storage compartment, or just raise them out of the way. Then, remove the spare tire, the passenger's side storage bin, and the access cover to the fuel pump. Separate the electrical connector by pressing down on the tab and pulling it toward the front of the car. Try to start the engine—it shouldn't start because the fuel pump has no current.

Next, remove the battery and washer tank. Remove the negative cable from the battery, making sure you have any security codes that might be needed when the battery is disconnected. Now, you should have good access to the fuel filter area.

Place a rag under the hose to catch any gasoline that remains in the rails, pipes, and hose. Using pliers, loosen the clamp and slide it off the hose onto the pipe behind the fuel filter. With the pliers, gently twist the hose and pull it off the metal pipe.

If the factory banjo bolt is still present, use a 19mm (or 3/4") wrench below the banjo bolt to hold the filter steady, then loosen the banjo bolt using a 19mm (or 3/4") socket and wrench. If the bolt is frozen or rusted to the filter, you can use a breaker bar to break the bolt free. Alternatively, spray the connection with penetrating oil first. After the bolt is loose, remove it so as not to drop the two crush washers that are on either side of the supply line.

Now, you can remove the fuel filter. After the flared fittings have been disconnected, remove the two 12mm bolts in the bracket that attaches the filter to the firewall. Don't drop or lose the metal inserts in the grommets that the bolts go through. Remove the filter and its bracket from the engine bay. Using a 10mm socket or wrench, loosen the long screw that holds the filter in the bracket and slide the filter out of its bracket.

Frequently asked questions