Possible reasons for burning SO much gas.

[Dragon]

sorry for bumping an old post but i am having some of the same problems.  i am definately not an engine person, i know the basics and can do lot of the work if i can read a manual or if someone tells me what to do its just i cant really figure alot of it out on my own.  i know the truck does need new spark plugs and probably new wires since i believe its all original under the hood. 

my question is when do you know its time to rebuild a carb?  and how tough would it be to rebuild a carter quadrajet if i have never done it before?  i want to wait until this spring to keep my truck on the road for the winter but if it didnt take long i would consider doing it here soon.

Sutton

Not to be mean or anything, but could you please post what year Truck or engine it is you are trying to bring back up to par???  The reason why I say that, is cause there are other things for the various years that could also be causing problems.  The above 1980 in the first post, I would also ask as to weither or not the Oxygen Sensor has been replaced, as one that is malfunctioning will also cause a problem with the engines fuel economy.

If your truck is older than 1980, then you might not have one (Some Cali cars and Trucks got them as early as late 78/early 79, depending on the vehicles use), but I would check to make sure.

The Charcoal Evap Canister has also been known to give difficulties, when they replaceable bottom filter is dirty enough, again depends on weither your truck came with one or not....

As for your Carb, is it a Rochester Quadra-jet or a Carter 4 barrel???  A Carter is Basically the Same as an Edelbrock Carb, and be a bit tricky to rebuild the first time out, but isn't too difficult.  If it is a Rochester Quadra-Jet, they are much easier to rebuild, after the first time you have done it. Personally I can rebuild a Quadra-Jet in my sleep, and am more than willing to tear it apart again when need be..  QJ's can be a bit more trickier to get them to adjust properly, but once you have, they can be one of the most Economical, and Performance Oriented Carb available.     When is it a good time to rebuild your carb??? For me, it is when I get a new car/truck, and I don't know if it has been done before(Especially if there is a good build up of dirt,grease, and etc present). Someone else, I would suggest that they do a rebuild, after they have preformed the basics(Ie replace Wires,Cap,Rotor,Module(if an HEI)/Points & Breakers(Also properly gapped/adjusted),Dist Springs(If Needed),Coil, and Plugs(ofcourse properly gapped). Once you have done all of that, then I would suggest to rebuild your carb...

[werewolfx13]

Not all 80 up vehicles had O2 sensors..AFAIK, none of these trucks got them til '87. I've never seen an 86 or earlier with one, including a 100% original '85 that my barber bought brand new..Only things that have ever been changed are fluids, filters, battery, and tires. Its still on the original plugs and wires.

[Dragon]

Not all 80 up vehicles had O2 sensors..AFAIK, none of these trucks got them til '87. I've never seen an 86 or earlier with one, including a 100% original '85 that my barber bought brand new..Only things that have ever been changed are fluids, filters, battery, and tires. Its still on the original plugs and wires.

In my Post I never stated that All '80 and up Vehicles got O2 Sensors, alot of them did, especially Cars/Trucks and Etc that were sold in California.    Personally I have seen Late '78- Early '80 Pickups/Suburbans/Jimmys/Blazers/Vans/RV's/Etc that were Originally order in California, Reside in near by States(Also some that were Shipped to Canada), and All of them Had O2's(mounted on a manifold) with the Cats(with Ebay, these trucks can migrate pretty far!).

I'm sure you have seen a 100% Original '85 (& even later on some models) without an O2 and possibly a Cat, O2's weren't mandatory till around '93 or so on all Vehicles.   As I stated in my previous post, neither SSgoodman, or 1980cdeluxe have their locations(State/Origin State of Said Vehicle) posted( In SSgoodman's case, he does give the year of the engine or truck he is working on), so I thought it would be a good idea to cover what hadn't been before.....

[JJSZABO]

Dragon, I read it as all 1980 and above also.     My 1986 c-10 did not have an o2 sensor, but it had (has)cats. 

With my limited knowledge, o2 sensors are used in computer controlled vehicles to help the computer regulate the air/fuel mix and to switch from "open loop" (when vehicle is cold) so it uses predetermined air/fuel tables to closed loop (when vehicle warms up) so the sensors regulate a/f mix.  The down stream o2 sensors only check to see if the catylatic convertors are there.

I don't see a need for o2 sensors on a carburator vehicle, unless the o2 helps the carb regulate air/fuel electronically.

As I said my knowledge is limited.  I am sure someone with alot more knowledge will pipe in.

[VileZambonie]

O2's are only used in feedback systems so either TBI or a carb that has the MC solenoid. Post Catalyst O2's were never used in these trucks and are pretty much OBDII