Help Please!!

[yukonlover89]

I have a 96 gmc yukon and at after about half throttle i lose power. Also i noticed that fuel pump is whining louder and it is only about a year old. Also when im goin up a longer hill i can only go about 40mph cuz of this lose if power and the check engine light comes on but will go off after. The code was the o2 sensor. Any help will be greatly app. THANKS

 

[treepete]

tell us more.
does the truck sputter before it totally loses power going up the hill?
your fuel pump..., you speak as if it were replaced recently... Can you tell us more about that "one year old" thing? mine whines too, but its done that for like 3 years... and the gauge needle wiggles by itself... but I've noticed no power troubles/konking out, etc.
tell us more about it. more specifically, do you get this CE light right away, or when its bogging or at a particular RPM?

my first thoughts are, inadequate fuel pressure, improper spark ( rotor/cap wires, misfire, etc) and then (since you said 'hill', maybe torque converter, but thats a long shot.

tell us more.

 

[yukonlover89]

yes it does kinda sputter but to leave out the torque converter when its in park and i hold it to the floor it only goes to about three and a half grand rpm and blows black smoke out and sound horrible if that helps

 

[yukonlover89]

and in addition i just changed fuel filters cuz i thought maybe it was blocked but no change

 

[GMCYukalade]

sounds to me like the fuel pump is giving up the ghost.. - that or you need a tune-up badly

 

[96ProCompTahoe]

if its blowing out a bunch of black smoke that would be unburnt fuel.

i'd lean towards the tune up.

 

[yukonlover89]

yeah thats what i was thinking but the yuke doesnt always to do this thou it doesnt do it when i first start it up it runs strong then so im stumped:nonod:

 

[yukonlover89]

and this engine only has about thirty k miles on it this is starting to get me very angry lol

 

[95TwinTT]

You are describing things that certainly could be the result of a O2 sensor taking a dump. I would go after that, especially since the computer itself is complaining about it. :yesnod:

 

[96ProCompTahoe]

a 96 with 30K on it probably sat around quite a bit. has it had a tune up? does it have a dirty Mass Airflow Sensor? if its blowing smoke you may have clogged up the cats or another 02 sensor.

may be as simple as needing new plugs, or a cap and rotor. pull a couple of the plugs and check the cap and rotor

 

[yukonlover89]

well the body has 100k but i replaced the engine a few years ago so you think it would be an o2 sensor and is there a way to check them?

 

[95TwinTT]

If you have a normal 96 Tahoe, the engine has four O2 sensors. There is one on each bank of cylinders, (left & right) that take readings ahead of the Cats. Then there is one sensor behind each Cat.

There are many levels of computer readout devices. The better ones, should be able to give you a clear picture of what is going on with the O2's.

Although not likely, a clogged Cat can also raise the same kind of symptoms you have had.

Either way, you need to get to someone that can get the complete readings out of your ECM. O2 sensors are pretty inexpensive. I replace mine about every 10,000 miles, but I'm abusing mine a bit.

You can do some tests on the O2's but it requires a working knowledge of how they function and a good meter. The normal voltage range of these puppies is zero to one volt for one version and zero to five volts for another. I'm not sure which ones you have.

The O2's were never intended to go forever. They operate in a very hostile environment.

 

[treepete]

I just had the local autozone read my engine light for me, and it was bank 2 o2 sensor. it also read pre-fail info for the bank one sensor. so yeah. mine lasted 119K and now need to be replaced. seems to run fine though.. but ill replace them cause I think they only about 40$ or so. maybe an easy one to try first for your problem?

 

[yukonlover89]

alright thank you so much guys

 

[yukonlover89]

well i found out what was causing my power loss.... the battery terminal was loose so there wasn't enough power for the fuel pump to run fast enough

 

[95TwinTT]

well i found out what was causing my power loss.... the battery terminal was loose so there wasn't enough power for the fuel pump to run fast enough

That does not make a log of sense. The starter would not have been very happy either, not to mention the headlights and eveything else. You also mentioned you had a code indicating O2 sensor.

If you are back to running OK, I would expect that it was intermittent and you should stay alert for other symptoms to show up. Just my .02 . :cool2:

 

[yukonlover89]

well i decided to check the battery when the other day i was coming home and i saw that the voltage was low on the gauge and when i turned my turn signals on the gauge moved way too much im not electrian but turn signals dont suck that much power lol but yeah its running like a champ and im looking to put a supercharger on it here soon :beerchug:

 

[95TwinTT]

OK, well, if you feel it is a voltage related problem, I would still keep an eye on it to be sure you found the culprit.

The system should be at 13.5 to 14 volts when running and a meter across a healthy battery will show 12.5 volts when the engine is not running.

I’m still curious about the O2 code. All four O2 sensors have heaters. They must be hot to operate properly. I have not run across it before but it may be possible a low voltage problem would not allow them to get hot enough to give accurate readings.

You should read the codes again now that all seems fine to see if that O2 code is still there.

What kind of supercharger are you looking into? That sounds like a fun project.