The fuel return hose is a fuel system hose that is found on vehicles equipped with carburetors. It’s primary purpose is to return excess fuel from the carburetor to the fuel pump, however it serves other important functions as well. Aside from providing a path for excess fuel to return to the tank, the fuel return hose also prevents vapor lock and over pressurization from occurring within the carburetor. Vapor lock occurs when the fuel pressure or temperature rises too high the fuel can begin to vaporize and cause issues.
Usually a fuel return hose is made out fuel resistant rubber, not much different from the rest of the hoses on the fuel system. This leaves it susceptible to the same wear and tear that regular hoses experience, such as drying out and cracking. Usually a bad or failing fuel return hose will display a few symptoms that can alert the driver of an issue.
1. Strong fuel odor, engine misfires, and decreasing power
One of the first symptoms of an issue with the fuel return hose is an excessive fuel smell. If there is any sort of issue with the fuel hose, either a leak, or some sort of kink that blocks the flow, it may cause the vehicle to produce an excessively strong fuel odor from the engine. The odor may be a result of leaking fuel, or of the vaporization of the fuel inside of the carburetor due to vapor lock. A vapor lock induced fuel smell may also be accompanied with performance issues such as misfires, a loss in power, and fuel economy.
2. Carburetor flooding, engine stalling, and hard starting
Another symptom of a potential problem with the fuel return hose is carburetor flooding. If the fuel return hose becomes blocked or kinked it may cause the carburetor to flood from excessive fuel or pressure buildup. A flooded carburetor may cause engine stalling and hard starting until it is cleared, or enough fuel has evaporated.
3. Fuel leaks
Another symptom of a potential issue with the vehicle’s fuel return hose is leaking fuel. If the fuel return hose becomes excessively worn or damaged, it may cause fuel leaks. A leaking fuel return hose may produce drips or puddles of fuel underneath the vehicle, as well as a noticeably strong fuel odor.
Fuel hoses play an important role in the operation and performance of the engine, and when they fail, aside from the performance issues, can even become a potential safety hazard. If you suspect that your fuel return hose, or perhaps another fuel hose, may be having an issue have the vehicle inspected by a professional technician, such as one form YourMechanic, to determine if the hose should be replaced.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Fuel Return Hose and was authored by Eduardo Ruelas.