Code 44 4.3 gmc safari

Some days I love this truck and some days I wud................ Anyways when I am towing my small camper about 2000 lbs loaded and trying to do the long haul up hills with ac on driving semi nice a
little ruff I guess...the check engine light has been comming on and I go thru a shit load of fuel like 300 km's per tank. The van gets rated 20-21 mpg when I am not towing ( crappy but that is what it is rated at) it is more like 8-10 when I am towing. And lo and behold the code I get (44 Oxygen sensor voltage was under 0.25 volts for up to 4 1/2 minutes of closed loop operation.) is for the one sensor I allready replaced. What would cause this reading? Could timming or just crap gas give this reading? What is that reading? Rich or lean? My guess is rich ie no or low oxeygen Carbon the cat con is now by passed as it was burned out anyways like the guts were gone straight pipe?
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Q) Why in the hell would we need to know the model year?
A) Because 4.3 liter engines in GMC Safari vans came as; 1) Carbureted 2) Throttle body fuel injection 3) Central Port Fuel Injected 4) Central Sequential Port Fuel Injected
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Oh ya oops 1994 w engine and yes the leaky cpi was replaced about 30 k ago
aarcuda69062 wrote:

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Under the conditions that set the code, your engine is under fueling (running lean). Possible causes are a weak fuel pump, clogged fuel filter, clogged injectors, skewed MAP sensor, skewed coolant sensor.
Doubt that it's a vacuum leak since it only occurs at or near wide open throttle.
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Ya figures .....i guess the only solution is trial and error and replace every sensor one by one one eh!
aarcuda69062 wrote:

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and the fuel pump might as well been left starnded by this before.....jeeze i miss the old days when 10 mpg was good.
no one that you know wrote:

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Yup. Swapnostics. (those test procedures are -so- boring)
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Look again at the advice you've been given (left intact below). Start at the beginning of the list of suggestions and work your way sequentially through it. Don't jump to the conclusion that it must be sensors. Sensors do not fail at high frequency. Typically when they report a problem they are reporting the problem correctly. Look at the problems suggested.
Have your fuel delivery pressure checked by a mechanic. Then work through the possible causes based on what that check reveals.
--

-Mike-
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I am going to replace the fuel pump first just because it has alot of k's on it. Been stranded by a pump b4. BTW how hard is it to change on this one...I havent even looked yet. I dont even know where the fuel filter is?
Mike Marlow wrote:

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no one that you know wrote:

Could also be that the sensor wire has an intermittent/bad connection OR is to close to something hot and the insulation is melted/damaged and it shorted out for a bit.
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Steve W.
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would this lean code cause the puter to dump more fuel?
"Steve W." wrote:

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I did some googleing and what seems to be making sense is a intake leak somewhere. After all it only happens when the throttle is open alot like hills or steady grade at 80 kmh and up when towing. I did replace all the leaky vacumm hoses allready but I must have missed something. Under load the ac vents used to go too defrost Climbing big hills it still does this the odd time? Where are the other common leaks on the 4.3 w engine? I do get a slight stutter when light accelerating of the line other wise it runs perfect. Could that be related to a vacumm leak?
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Please - follow the advice you have been given. You can easily get yourself all twisted up researching the hell out of things and drawing conclusions based on not too much. You may well have more than one problem in your vehicle, but if you don't conduct a methodical series of tests and/or replacements, you're only going to cause yourself more problems. You might even get lucky and actually fix one problem (even a blind squirrel finds a nut sometimes), and you'll not even know what really fixed it because you've been shotgunning all around your vehicle in a helter-skelter manner. Or... you may introduce more problems.
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-Mike-
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I wouldnt say what I have done so far was helter skelter ....all the vac lines were rotted right out.
Mike Marlow wrote:

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I wasn't speaking about what you had done already, but what you were doing as a going forward strategy.
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