1989 f150 exl lariat

For your twenty-five year old truck, with I suspect a LOT of miles on it, it could just be worn out. I don't know why you're concentrating of filters as leaks at filters will almost always produce a puddle below a leak. I think you have engine gasket leaks or injectors that are leaking and flooding the engine. The engine's loose and allowing gasoline to migrate into the oil and that's what you smell. I also suspect that this has been going on for a long time and is now the cause of the knock, as gasoline in engine oil reduces its lubrication properties and has now damaged bearings. I also suspect that this has damaged the catalytic converter. Good luck finding a mechanic to work on anything pre-1996 (OBDII), as this is likely what you're going to need.

For your twenty-five year old truck, with I suspect a LOT of miles on it, it could just be worn out. I don't know why you're concentrating of filters as leaks at filters will almost always produce a puddle below a leak. I think you have engine gasket leaks or injectors that are leaking and flooding the engine. The engine's loose and allowing gasoline to migrate into the oil and that's what you smell. I also suspect that this has been going on for a long time and is now the cause of the knock, as gasoline in engine oil reduces its lubrication properties and has now damaged bearings. I also suspect that this has damaged the catalytic converter. Good luck finding a mechanic to work on anything pre-1996 (OBDII), as this is likely what you're going to need.

There is a fuel strainer in the fuel tank, a main fuel filter in the frame rail, now each injector has a screen built in and it is not serviceable. If you smell fuel then you have a fuel leak, check the fuel pressure regulator, the fuel tank switching valve, the fuel vapor system.

Yes, check the vacuum hoses associated with the EVAP system. Most likely one is leaking fuel vapor and that's what you're smelling. Hope that helps! Jim