1. Fuel Pump Issue: The fuel pump may be faulty or not receiving power, which can result in no fuel being pumped to the TBI. Check the fuel pump relay, fuses, and wiring to ensure that the fuel pump is receiving power. You can also try to listen for the fuel pump running when you turn the key to the "ON" position. If you don't hear the fuel pump running, it may need to be replaced.
2. Clogged Fuel Filter: A clogged fuel filter can restrict the flow of fuel to the TBI unit. Locate the fuel filter and inspect it for any dirt or debris that may be blocking the fuel flow. If the filter is clogged, replace it with a new one.
3. Faulty TBI Unit: The TBI unit itself may be faulty and not functioning properly. Check the electrical connections to the TBI unit and ensure they are secure. You can also try cleaning the TBI unit with a throttle body cleaner to remove any dirt or deposits that may be affecting its operation.
4. Fuel Pressure Regulator Issue: The fuel pressure regulator helps maintain the proper fuel pressure in the fuel system. If the fuel pressure regulator is faulty, it can lead to insufficient fuel pressure, resulting in no fuel past the TBI. Check the fuel pressure using a fuel pressure gauge to ensure that it is within the manufacturer's specifications. If the fuel pressure is too low or too high, the fuel pressure regulator may need to be replaced.
5. Leaking Fuel Injector(s): If one or more fuel injectors are leaking, it can cause a loss of fuel pressure and result in no fuel passing through the TBI. Check the fuel injector seals for any damage or wear and replace them if necessary. You can also try cleaning the fuel injectors to remove any dirt or debris that may be affecting their operation.
If you have checked all these potential issues and still no fuel is past the TBI, it's recommended to consult with a qualified mechanic or refer to the vehicle's service manual for further diagnosis and troubleshooting steps.
