The Main Fuel Relay (part#: 39400-sh3-003) on 90-93 Integras is a major problem. Most of the time these relays end up going when severe hot weather suddenly rolls in. What actually makes these relays malfunction is the solding inside the casing cracking. This creates a "loose" connection in the relay causing the car to sputter or not run at all. A new relay from the dealership or a foreign parts store will run you anywhere from 40-50$

To remove the Main Fuel Relay you will need these tools

-Ratchet with Extensions

-Soldering Gun (Any Type)

-10mm Socket

-A Small Flat Head Screw Driver

-Wire Brush and/or Small File

-Philips Head Screw Driver

1st - Disconnect the cable from the negative battery terminal

2nd - Unscrew the 3 screws that hold the drivers side under panel in place

3rd - With your 10mm socket, unbolt the two left bolts that hold the metal panel in place

4th - You should see the relay to the back of another relay that is black, its facing toward the fire wall

5th - Unbolt that 10mm bolt that holds the two relays in place

6th - Disconnect the wire harness from the Main Fuel Relay (Brown Box)

7th - Now that you have the relay out, take the small flat head screw driver and pry the cover off

8th - You'll see at the top of the relay there are some solders and if you see any crack in the them you should fix them.

9th - Take your solder gun to the solders and twirl them around a little bit to make a good connection

10th - Clean up the solders with a wire brush or a small file

11th - Reinstall the relay, connect the battery, turn the car to the "ON" position and listen for a click to come from it. If you hear a click then you were successful.