no matter what i do to my truck, or how i drive it, i never get more than 13 mpgs. when im sitting still idling, the truck stinks like gas. it also sputters and sometimes stalls when it starts up after sitting for a few hours (and then it REALLY stinks like gas). fuel pressure regulator is about a year old and motocraft with no raw fuel in the vaccume line. cap, rotor, plugs, wires, all that good stuff is either new or within the year. im thinking i have a leaking injector. is this possible? would a bad injector throw off a fuel pressure test? my air rail is leaking again so if i tear everything apart id like to diagnose the fuel injector. -thanks

 

What motor and tranny and gear ratio do you have? I have a 351w with 3.55 gears and a 4 speed with no OD and I get 8 if I drive it nice. I've gotten 6 beating it mercilessly.

 

The text in bold is more than likely the cause of your rich condition. A leaking air injection line, just like an exhaust leak, sucks in air as well as allows air (exhaust) out. Any leak in the exhaust or AIR system upstream of the O2 sensor can trigger a false lean reading, which in turn causes the PCM to dump in more fuel.

Your other question "would a bad injector throw off a fuel pressure test?" would be an answer of affirmative. A leaking injector will bleed off pressure too quickly. If may not affect the overall pressure reading but there is a specification for how long the system should hold pressure.

 

Come to think of it, my o2 sensor threw a lean code last time I scanned my truck (about a week ago). I just cleared it out and didn't think anything of it. I just replaced the air rail about a year ago. Very annoyed to have to do I again, and that's if it even fixes the leak. As for the fuel pressure test, I never let it hold the pressure. I just got the reading I wanted a moved on, so I wouldn't have noticed the bad injector. I'm glad I'm getting more spot on info though.

 

Truck in sig. 300 with 3.55's and 5 speed. It just bugs me that I get the same fuel economy driving like an old man or driving like I'm in a rally race.