I was changing my oil last night and before I put the filler cap back on for some reason I smelled it. Well, I smelled a hint of gas and so I asked my wife to see if she smelled gas on it and she said yes. So my question is what does it mean when you smell gas on your oil filler cap??

 

Some hydrocarbons will make their way into the oil no matter what, that's normal. If it smells like raw fuel, I'd check for a possible rich condition...check the spark plugs and see if they're black. Other possibilities are a leaking fuel pressure regulator or an injector leaking down. Either of those problems should cause a rough start condition though.

 

How do you test for a leaking injector?

 

Honestly, I'm not sure on our trucks, but there's a few different ways, depending on the fuel delivery system...what I've done in the past on other manufacturer's vehicles (with return lines) was to put a guage in the system, fire up the fuel pump (there's usually a test pin that can either be powered up or grounded...on Toyota it used to be jump fp to b+), make sure the return is clamped off, and see if the system holds pressure, which it should. If pressure drops rapidly, then there's a leak somewhere. (this test is done while the vehicle is not running)

You could always check the cylinders with a boroscope after the vehicle has been sitting for a while...if a certain cylinder may have a suspected leaky injector, turn the motor over by hand until that intake valve opens, then stick the boroscope in the spark plug hole and check for the presence of fuel.