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Low fuel pressure and poor running


timpage

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I haven't pulled codes in a few weeks (and have replaced a few things since). Probably tomorrow I will get the codes pulled and share. No check engine light on, though I know that there likely are stored codes (as there was a few weeks ago... but don't recall what they were...)

I can also pull the connection to the O2 sensor at that time and see what affect that has. Not to eliminate the O2 sensor as a suspect part, but it was replaced shortly after I bought the truck (early June) with a cheap replacement... the O2 wiring hadn't been tied out of the way and burnt through from laying on the exhaust pipe.

Ill also check out the broncoii.org website for clues too. Thanks.
 
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timpage

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OK, pulled codes this evening. KOEO, only pulled 11 (passed). KOER, pulled 42 (rich) and code 77 (?).

Once the engine warmed up, I took the truck for a spin (about 6 miles total) with the O2 sensor unplugged. Smooth running, no hickups. Idle was smooth, normal RPM (800-850).

So does this mean I have a bad O2 sensor or bad O2 sensor wiring? Or are there other issues? I do know I have an exhaust leak (right exhaust manifold leaks at #3 exhaust port, bad gasket). I know this will have an effect on causing to run rich (and the code 42). However the exhaust leak has been there since I bought the truck and long prior to the sudden idle/running problems.

Any input on this?
 

timpage

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Curiosity got me. I pulled the O2 sensor tonight to check it out. The the tip (the tips core) was deteriorated and broken into chunks inside its protective case. What would cause this? It was a cheap one, would that be a factor? I'm buying a replacement, what quality brands are recommended? Thanks
 

timpage

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Manual
Replaced the O2 sensor today with a new Bosch unit. Put 20 miles on the truck this afternoon with good results.
 

freedom5

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Yes, under load pressure drops to 22-24 psi or so. The truck will sputter and sometimes dies stopped/ brought to idle. Cold idle when the truck is first started is pretty irratic but stabilizes. Warm idle is better, but still with some milder fluctuation.
I had some similar problems about a year ago. Couldn't get it to accelerate very fast and seemed sluggish. I checked the inertia (it's either on or off), added Chem B-12 to the fuel tank etc.. I decided to change the fuel pump relay which operates the high pressure pump and found the relay connection was full of corrosion. Cleaned the contacts and installed a new relay and now everything works fine. I am assuming the corrosion in the relay reduced the voltage to the main fuel pump.

Hope this helps. Freedom5
 

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