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Diagnose fuel problems

damagexinc

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City, State
Melrose Park, IL
Year, Model & Trim Level
'99 xlt
Im going to be checking my fuel pressure today to see if it's the reason why im getting code p1151, which says it's either the MAF, a vacuum leak, or high/low fuel pressure do to leaking fuel regulator or injector. After i do the test and find my psi how will i know what the problem is?
 




2000StreetRod

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Greenville, SC
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00 Sport FI, 03 Ltd V8
O2 sensor replaced?

P1151 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2

This is the same problem that you've had for some time. Did you ever manage to replace the O2 sensor on the driver side?

If your MAF sensor or fuel pressure were incorrect it should affect both banks not just Bank 2 unless you're at the limit. I know that you have checked for vacuum leaks and found at least one. If the O2 sensor is new then you may have a blocked injector. Have you tried adding fuel injector cleaner to your tank?
 




robertoa1a

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Jacksonville, FL
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96 5.0 xlt 2wd white/char
If it were running rich on bank one then the PCM may chose to over correct by leaning out the mixture on both banks causing bank two to run lean.

The third plug on a v6 can be extremely hard to get to and I have seen folks just leaving the old one in replacing the other five. It seems like you would get a cylinder misfire code if this were the case, but maybe not if the plug is still firing somewhat.

You may have a vacuum or exhaust on bank two. Check the PCV valve.
 




damagexinc

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Melrose Park, IL
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'99 xlt
I did change the o2 sensor and this code keeps coming back. I replaced the maf and checked all vac lines and have reset the computer after each fix. The desription I posted above is what autozone's read out told me. I'll double check the pcv tomorrow. The only problem I can tell I'm having physically is a slight misfire when idling. I'll check that third plug and see if it has more wear than the others then give the truck a tune up if so.
I doubt its an injector/plug problem because as you said shouldn't I be getting a spcecific code for that cylinder?
 




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