i have a 1997 ford f-150 4.2 liter. i bought it from a friend. he said it needed a head gasket. i was 100% ready to take on this job being that the truck is in such nice looking shape. clean, new tires, etc etc. talking to a mechanic, he told me a few tests to run through since it wont start. it turns over very easily but emits a very strong gas dor. first, i checked the fuel pressure regulator and it read to spec. i replaced the spark plugs and made sure i had spark to each one. still no start. i then did compression tests on each cylinder and and three with no compression. the other three had different readings on each one varying from 40 to 150. isthis signs of burnt vavles or am i totally missing something. at this poin, im willing to do head gaskets but was told i may not be solving the problem. help!!!!!
thanks
nick

 

Welcome to the forum.
Does the oil smell like fuel? I would get a noid light (most autoparts stores have them in the tool section), and check the fuel injector pulses when cranking. Each one should briefly flash as it cranks. If one or more stay solidly lit, then the PCM has stuck injector drivers and is flooding the cylinders with fuel. I have seen this happen on several Fords from the 90's era. If this is the case, the rings are probably shot and an overhaul is in order.
I would say from the compression readings that there is a good possibility that the heads could be warped as well as the gaskets being blown. It's just hard to say without tearing it down and looking.

Oh, I moved this to the 4.2L forum so you will get better advice since it is engine specific.

 

sounds like a plan. thanks for the advice.
nick