What are common reasons my Lexus GX460 has a rough idle? While there are a variety of reasons your Lexus GX460 has a rough idle, the most common 3 are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil. 34% of the time it's Apr 27, 2011 · 460 EFI running very rich - posted in 80-96 Ford Truck Tech Support: I just got an 88 F-Super Duty with a fuel injected 460, and it is running very rich. I replaced all the obvious stuff, temperature sensors, air filter, PCV, spark plugs, cap and rotor, and no better. I went on to replace the MAP sensor, nothing. It still smells crazy rich, is smoking, and the brand new plugs (well, all but ... Jul 17, 2014 · Crack open all three injector lines at the injectors (normally a 5/8" wrench). If you can't get diesel to the injectors by cranking, try tow-starting it in 3rd or 4th gear low range. It takes a lot of cranking to fill the lines - the pump puts out a very small volume at high pressure.