Anybody got any suggestions on what could be the cause of my egine running lean? I recently Replaced the sparkplugs sparkwires, changed the oil, Replaced the Air filter (3 months ago, but since the Valley's air sucks like hell it looks like its been in for years) I know im burning oil (and its getting up into the Air filter area) Im at a loss
by the way it is a V6 2.8l Carburated

Firebreed

 

clogged fuel filter? old o2 sensor?

and when was the last time the carb was rebuilt?

 

No clue on the Carb rebuilt because the egine wasnt well maintaied before i bought it , ill check on the O2 senson, And i have no clue where the fuel filter is located at on the carb.(new to working on cars)

 

your best friend will be a book called chiltons or teh "holy book" haynes.

we will be your best virtual friends.

 

i got the Haynes manuel... And ill make sure ill do what it says.. but ive done everything within my fincal range right now maybe ill go for the new 02 sensor first?


Firebreed

 

i'll bet you a diet Bear **** that you should rebuild the carb before touching the o2 sensor.

 

Let's make this easier.
Who did the swap of the 3.1 under the 2.8 set up?

 

First off, how do you know you're running lean? Do you have a code? Do you have an A/F Sensor? Are you guessing?

i wouldn't touch the carb until you know for sure that everything else is working like it should be, because if that's not the problem, it'll be an expensive waste of time and money. Chekc to be sure that all the sensors are functioning correctly and the the M/C Solenoid works. Something that happens all the time, especially on the Quadrajets(which this carb is, just missing the secondaries), is that people think that they will adjust the carb and then they mess with the M/C solenoid limiting screws, and screw everything up. The car will either run super rich, or super lean all the time. and then the problem is compacted by shops that rebuild them not knowing how to recalibrate it.

There is a special tool that is made for doing this. All it really is is a ruler that is calibrated in 1/64" increments. It comes with the instructions on how to adjust it, but you have to hunt it down and order it. 99% of the time, if a Computer controled carb is not dispensing fuel corrrectly, and all the other sensors are functioning, this is the problem. i have seen many of these carbs come back from being rebuilt and they don't run any different because someone screwed with the limiting screws.

 

I know its running lean by putting a diagnostic mashine up to it (at my local Navy base Auto Hobby shop) And it pulled no codes but informed me that it was running lean, im goning to end up replaceing the Carb anyhow so if that is the problem then hopefully it will be fixed.

Firebreed

 

QUOTE]Let's make this easier.
Who did the swap of the 3.1 under the 2.8 set up[/QUOTE]


Orginally i thought it was a 3.1 but i looked at the emissions tag and it was a 2.8 noob mistake, i replaced the O2 sensor and the car runs a bit better (not stalling out as much) i did fool around with the idle screwand i found that if i when one rachit click clock wize the idle would go up, to about 1000 rpm's and one rachit click down would cause the car to utterly stall (all when the car is not warmed up, when warmed up it idles fine) any ideas (and sorry for the delay)

 

Hey Firebreed, that be a Varijet on that thing! Pull the evap canister line off the carb and see if it's full of charcoal. I've seen the canisters come apart and pull charcoal up into the secondary metering rod hole and make them run lean.

 

Checked that out, no charcoal in there, I did find vacume source on the mainfold behind the carb, in front of the distrubtor (not on it) and im not sure where that goes to, i pluged it up for now, and it the car is idelling a lot smoother, i replaced the o2 sensor, and the car is getting better gas milage and running better, but the car is still stalling when cold.

Thanks for all the help,
Firebreed

 

Replacing my Coolant Temp Sensor sure did help me with some problems.
BUT your version of carb it may not be there.
Go to GM dealer and seek coolant sensor to see if that is something to replace. Mine cost $16 or even less if ya get it without the connector. Mine was located next to thermostat housing.

 

Well, I believe i fixed my lean problem, i replaced my O2 sensor, and now im not haveing any lean problems, however i did find a Vacume source on my manifold, which was behind the carb and infront of the dizzy, Im not sure what it is so i pluged the thing up and now, shes runnin smooth (until i hit around 80 miles an hour and the hole car shakes like crazy, need new tires )


Firebreed