99 stalling and losing power to fuel injectors

[GraderJC]

I have a 99 ford expedition problem that has stumped me and my brother in law for awhile. When the car is first started it will run fine for about 10 minutes. Then randomly the engine will begin to cut out and idle rough. It will randomly stall and if the key is left in the on position after stall it will crank but no start. When the engine stalls the PCM will randomly throw out a number of codes but once whiped it never throws the same ones twice. I checked all relays, fuses and grounds. changed the battery, fuel pump, crank and cam sensor and still nothing. We spent about 4 hours driving around, back probing and testing the pcm power and grounds and everything was fine so we thought it had to be a faulty pcm due to it throwing out random codes. Replaced the pcm and programmed the keys. Drove it about 15 miles and then the problem persisted. We noticed that every time the engine dies and the key is left in the on position, there is no power to the fuel injectors when cranking, also the gauges on the instrument cluster drop to zero and the car will crank but not start. The second the key is turned off and back on the car starts just fine. Someone suggested to us that it is the PATS system malfunctioning and causing the injectors to lose power. Note that I still have spark and fuel and the fuel pump holds pressure and primes, only the injectors and instrument panel lose power. Any advice would be greatly appreciated as we have done every test we can think of and can't find any info on this sort of problem.

 

[stamp11127]

How are you checking for power to the injectors?

 

[1955moose]

You should be using a noid light on your injector for testing power. At least that's what I've always used.

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