Locate the fuel relay. In the Volvo 740, the fuel relay is located in the engine compartment, on the driver's side near the firewall. It is a small, black box with a few wires connected to it.
Check the connections. Make sure that the wires are properly connected to the relay. If any of the wires are loose or damaged, this could cause the fuel relay to malfunction.
Listen for the relay clicking. When you turn the ignition key to the "on" position, you should hear the fuel relay click. If you do not hear a click, this could indicate that the relay is bad.
Test the relay with a multimeter. You can use a multimeter to test the relay's continuity. To do this, set the multimeter to the "continuity" setting and connect the probes to the relay's terminals. If the multimeter reads "open," this indicates that the relay is bad.
Replace the relay if necessary. If you have determined that the fuel relay is bad, you will need to replace it. To do this, simply remove the old relay and install the new one in its place.
Once you have replaced the fuel relay, start the engine and check for proper fuel flow. If the engine starts and runs normally, this indicates that the fuel relay was the problem.
