'99 4.2l running VERY rich - Ford Truck Enthusiasts Forums


'99 4.2l running VERY rich

Old 02-18-2013, 12:29 PM
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'99 4.2l running VERY rich

Hey All,

Ok, I'm done beating my head against the block and need some help!
This van has sat for 4 years with a bad fuel pump. I replaced that, got it "running" and have these issues.
Here's my scenario:
When starting the engine, it runs fine for about 1-2 minutes. At that point, it seems like something kicks in and it begins to idle very rough. Black exhaust comes out and I can hear the motor begin to load up. I punch the accelerator a few times, it clears up for a moment then begins to load up again. No obdII engine codes are thrown and no pending codes.

Here is what I have done so far:
1) New MAF sensor
2) New plugs & wires, correctly gapped
3) New fuel pressure regulator
4) Checked for any vacuum leaks and replaced bad hoses
5) Checked the Cats for any blockage in the exhaust.
6) Replaced a bad bushing on the manifold valve solenoid
6) Double checked my work to see if any sensors were left unplugged.

I've read the threads about the intake manifold gasket going bad allowing too much air in, but logically wouldn't the rich condition occurr immediately after starting??

Any insight would be GREATLY appreciated.

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