Intermittent "stumble" on cranking

n5926g · #1 (**permalink**) 07-05-2009, 04:07 PM

Hy Guys,
Ive got an annoying problem with my 97 4.2...Occasionally when its first cranked up it will shake like the dickens.About 50% of the time it will "catch up" and idle smoothly,and the other 50% it will die. If I attempt to crank it right away it fires up normally.

Fuel filter has been replaced,as well as a good cleaning of the IAC etc.
This only happens when its been sitting overnight,or at work when im in the office for 8 hours or so.Otherwise driveability is excellent(for 168,000 miles)...suggestions? there are NO codes,and the CEL lamp is operational.

Ron W. · #2 (**permalink**) 07-05-2009, 04:21 PM

Not "up" on the 4.2 but if it only happens after sitting for 8 hours or so and starts right up after it dies, could it be your fuel is draining out of the fuel injector feed rail? Nothing more than a guess ...

n5926g · #3 (**permalink**) 07-05-2009, 04:27 PM

Very good point..I have actually thought of possible weak/leaky injector(s) causing the problem.Im sure these are the original injectors.If the fuel rail pressure drops(while sitting overnight) I could see where it would cause a problem like this.Cant think of any other reason that the pressure would drop off unless there is a valve in the system that prevents"bleed back" into the tank.....Im just not completely convinced its a fuel deliverey problem...yet.
Thanks for the quick reply.