Noob needs help with sh!tty mpg...

So, I have an 86 B2000. Im rocking about 12-13 mpg....Not really what i was looking for lol. Here are some things I have noticed wrong that may contribute to this. I drive 5 mile one way to work, They temp gauge never moves off cold. I am going to check if there is even a thermostat in the truck and add or replace it. When I start the truck in the morning, it idles at about 2k rpms and works it way up to about 3k rpms. It stays at 3k till I tap the gas pedal then it drops back down to around 2k again. Once the truck has been running a while, it will idle around 1k.
Plans for today include fuel filter, thermostat, and maybe tinkering with the carb.
Any ideas on what would cause my awesome gas mileage?
Thanks in advance.

Your poor idling may be a choke issue. Might want to ensure that it is properly opening / closing.

I'm not an expert on carbs, so excuse my extremely technical language. I used to have the same issue when I first started driving my truck where it was doing almost the same thing. There was an arm right next to the "barrel" on the outside that connected to the choke. Somehow it was not properly connected. If I remember right the linkage to some diaphragm was not together, like it was slipping out. I took a bread tie and used the tiny wire to secure the arm together so it would open correctly. Ever since it's idled correctly.

If its the factory carb trash that shit. Same problem with mine

The factory carbs work IF cleaned and maintained! Granted a headache to a degree,but you might need to do a rebuild and clean the inside out,etc.The float,air-fuel solenoid are major components that need attention and just doing a good tune,plugs,wires,cap,rotor,oxygen sensor, just too much to list.Sounds like your HI idle arm sticks ,egr probably needs to be cleaned below the carb 3 ten mm bolts,one vac line,one elect plug,remove it clean carbon with carb cleaner.Tired so stopping here.I am running stock since 1987 and works fine.Just the alternate side of things.

Where ya' at? In 5 mile drive - if it's cold outside - you may not see the gauge actually move up.
Yes, easy to try a thermostat, get 192/192F.

Engines work way better once warmed up, less wear and more efficient. So that and high initial idle could be most of your issue.

Yes, the stock carbs are extremely complicated, no one will dispute that. But they seemed to work OK until they got used/old/overused. Myself, I have a Weber, 6 years now, runs good, but that did not improve my mileage, I get 19 mpg in my 1988 Cab Plus.

I agree with 87forever.....if the stock carb is cleaned and maintained, it will work way better than the Weber carb will. I've had both, and I'm very capable when it comes to working on a carb........in other words, I'm an old guy and grew up with carbs, not EFI!
There is one thing that can go bad, or more likely, get clogged and dirty and therefore hinder it's normal operation, and since the stock carb is a "feedback" type of carb (it is regulated by the computer), if any of the "sensors" (mainly the oxygen sensor) give the computer a false signal or voltage reading, then the computer will enter a "Limp Mode" setting which will richen the fuel mixture during idle. There is a metering solenoid (Mixture Control Solenoid) in the center of the carb that will control fuel flow for the idle circuit (I'm pretty sure that's what it mainly controls) so if the computer has opened this thing up to allow more fuel flow (to prevent an overly lean condition) during idle, it will really hurt your fuel mileage. When your cruising it probably keeps adding fuel as well because it's going to stay fully opened until the problem is fixed that's causing the computer to get the signal(s) it's getting.

Read this also.....



That Mixture Control Solenoid can get trash in it also and that could render it faulty, it is a fairly well built unit and I doubt that the unit would go bad under normal operations, and they're expensive to buy new, plus they have a O-ring at the top and bottom of the unit that seals it to the carburetor castings that it is mounted in......if these are bad, cracked, leaking, your not going to get good mileage as well!

First thing I would do is to check or replace the oxygen sensor, as this is the device (you might even be able to clean the one you have in it and get it working again IF that is the problem) that tells the computer what the carburetor needs as far as fuel goes.

Post some pics of the truck also!

Excellent replies.
Hello, this is your id:
We know it is strange for us to speak to us rationally but this is what we want.
What we really want is a Weber swap.
So if we're having problems... perhaps it could bump up that weber swap that deep down inside we really want to do
Here's some endorphins to seal the deal.
Kind regards,
Id

Hello us, meet the real me, this is our Ego talking.
That maniac Id has been talking to us haven't we?
Well sometimes we make sense and we're inclined to agree with us.
Kind regards,
Ego

Holy crap, is it true, can this be possible?
We are always telling us to act responsibly and that usually runs contrarily to that impulsive irresponsible ignoramus Id... but we're inclined this time to agree with us.
Your's in health, Super-ego

Lol that's hilarious I will be goin weber soon because of this lol j/k. As far as the rest of these posts go it was very helpful. I have these same problems but mine doesn't get to 3000rpm it goes up to 2k, but I thought it was because I live in MN and its on average 32* or less during the winter months. So I figured it was warming itself up.