Alright, I'm about to go insane. It's a carburetor. Why the heck can't I figure it out...

The thing is running insanely rich. I'm getting about 10 mpg with it, if that, and I can't even get up to speed hardly. Getting up to 30 mph is painful. When you give it gas accelerating or driving, it spits, sputters, and blows all kinds of black smoke out the exhaust. Plus, it's getting worse. It used to just be a bit annoying, but yesterday I was on a 60 MPH road and it took me about 4 miles with people honking and cussing me out to get up to about 50 and it wouldn't go any faster. I have a weber but I don't want to spend the $50 for the adapter plate and linkage that i would have to have. I bought a set of torque thrusts for my el camino and that kind of has me in the hole for the time being.

Anyways, sorry for my rant. What could make it run so dang bad? It's an 80 with a 20r. I blocked off all of the vacuum lines ( excluding the vac advance and booster) so i know a vacuum leak isn't the problem. I'm clueless as to what could cause it.

I'm tempted to make my own adapter and linkage and put a Rochester 2 jet on it. It's simple and doesn't have 1700 vacuum ports and all kinds of unnecessary crap on it.

Thanks everyone..

 

Screwed around with t some more, and I found that when I disconnect the fuel shutoff solenoid ( that is what that is, correct?) it runs a LOT better. I can floor it, do whatever I want and it goes... But, when you come to a stop, it won't idle, and it backfires trough the exhaust when decelerating...

Shouldn't it not run at all with that disconnected?

 

Sounds like your needle/seat/float may not be working right. These symptoms have happened to me twice, both times there was a piece of crap stuck between the needle and the seat.

 

Just pulled the carb apart again and cleaned everything. Needle and seat are fine, and the float is fine. Put it back together and drove it around the block without the air cleaner on it. Ran good. Got home, put the air cleaner on it, drove it and it ran like crap. When I said that unplugging the solenoid in the carburetor made it run better, it was was really because the air cleaner was off.

It has a brand new element in it, and I can see plenty of light through it. The only thing I can think that could cause anything is where the air cleaner is hooked up to the valve cover..

I'm thoroughly confused.

 

Yeah that is confusing, cause a brand new filter element should not cause any real difference in flow with ou without it on. Have you tried running it with the filter and then trying to unplug the hose running to the valve cover to see if it makes a difference?

 

I haven't but I'm going to.

 

Ok so from what I understand the truck runs rich, which these tend to do on stock carbs. Here are my suggestions assuming this is a stock carb, I didn't see where you said if it was or not.

1.) If the fuel cut-off solenoid is disconnected the truck should never run. Your options are to test by unplugging it and putting 12V straight to it and listen for a click sound to determine if it works or not. If not, you can always buy a plug at a local hardware store to eliminate the solenoid. With no solenoid, you will get some sputtering and such when the engine is turned off.

2.) Next get the truck to idle and look on the front of the carb at the fuel sight glass window. The fuel level should be a hair below half way in that window. Adjust the float if needed.

3.) You say it runs a lot better with the air cleaner off? Not sure what to say about this other than to check your timing. The only thing that should affect this is a seriously dirty air filter. Also once the truck is warmed up and at idle the choke flap in the stock air cleaner should be open to pull air out of the normal intake and not to pull air from the heat shield on the exhaust header. You can pull the vacuum hose off the choke and see if it will move while you suck/blow in it.

4.) Set the fuel/air ratio screw back to factory setting. With the truck off turn the screw all the way in and then 4 full turns back out. With the idle screw set the rpms to ~800.

Try the things above and see if that helps at all. If you do not know where the fuel/air mix and idle screw are on the carb look for the thread to download the FSM in my signature. It will show you.

Another general note is to check the conditions of all your vacuum lines. If they look the slightest bit dry or cracked, replace them. I run a stock carb that is de-smogged. I rebuilt my carb with a kit from LCE, de-smogged, replaced the remaining vacuum lines and my engine ran so much better than after that.

 

Solenoid definitely clicks when it is plugged/unplugged, and it seems to make it run lean (naturally). I'm not sure why it's keeping it from dying. What does the solenoid do? I pulled it out but there are no moving parts or anything sticking out of it.

I recall the fuel in the sight glass being about 3/4 way or a little better up the glass. I'll set the float accordingly.

It does have a stock carb. It's completely stock. All un necessary vacuum lines are unhooked (no emissions check here), and the ones that are hooked up are in good shape.

Does the screw need to be out 4 turns? Not saying that you are incorrect but I've read that people generally set it at 1 1/2 turns out. Just checked and it makes no difference in how it runs if the screw is all the way in. The screw I'm turning is the (only) one I see about mid-carb facing the passenger side of the pickup.

Thanks!

 

The solenoid is powered off switched ignition power. Once it has power it allows fuel to flow in the carb. Once power is removed it should cut off the fuel supply to prevent the engine from stumbling and sputtering when its cut-off. I'm not sure if you can see any moving parts or not when it is removed and power is put on it.

As for the hoses this is the diagram from the FSM showing the necessary hoses for correct carb function.



The screw is four turns out from the factory. Obviously its up to you to fine tune it after that. I was saying to maybe set it to 4 turns out and lean it our from there.

 

I had a similar problem when I got my '83. I was getting 8-10mpg with the stock carb and it wouldn't even pull 5th gear. It also had 33x12.5 tires with stock gears so that didn't help the issue either. I know my way around carbs very well and I still couldn't get it running right. After new spark plugs, wires, distributor, fuel pump and desmog it still wouldn't get right. I ended up slapping a Weber on it and never looked back. I ended up getting around 20mpg on a worn out motor before I rebuilt it.

After I removed my factory carb, I learned that the idle mixture adjusting screw is plugged with a steel plug by the manufacturer. I noticed that the previous owner (who apparently is an idiot and should never ever ever pick up a wrench) had removed that plug and fiddled with the idle mixture then re-plugged the screw with a rubber plug. Per the FSM, the idle mixture screw should be backed out 4 full turns from bottoming out. He had it backed out 6 full turns! I never confirmed, but that was likely my problem. If you do not have this idle mixture adjustment correct as your baseline then all of your other adjustments will be off completely.

If you want to keep the Aisin carb then start by verifying your idle mixture adjustment first, but I would recommend getting a Weber and leave behind your Aisin woes.

 

Figured out the problem. There was no vacuum line going to the vacuum diaphragm on the air intake. I just took it out because it doesn't need 2 chokes. It really doesn't even need one.

Thanks for the input everyone.

 

Hi, i have an 86 22r. i'm pretty sure i had a clogged fuel filter one day, because when i went to start it, it fired up idled for a about 5 seconds and then died. and wouldn't start again. so i dumped all the gunk out of the fuel filter. this is where i made my mistake, i looked by the carburetor to see if there was a secondary fuel filter. i found what i thought was a secondary fuel filter. it looks kinda like a lawn mower fuel filter. the pic that was posted on this thread shows its a jet. i took it off and tried to blow through it and i couldn't blow through either end of it.i tried to take it apart to clean it and broke the part where the vacume line attatched. so i connected the vacume lines strait to each other without the jet and when i started it, it ran better than it did before, now when i barely tap the gas it seems like your stompin it about half throttle and had more power than before and didn't seem to run as rich. it ran pretty rich before i had this problem. so i went to Oreilly's auto parts and they said it was a vacume valve of some sort. so i bought what they said was a universal vacume valve i put it on and it seemed to have more power than when it ran rich. i dove less than a mile home and the idle started going from high to low once warmed up. i tried setting the mixture screw to factory which i heard was 2 1/2 turns out. it runs fine when cold but when it warms up and i go for a half mile drive an git back it wants to die and starts spittin ana sputterin and a lil black smoke is involved.

please any tips, tricks, or advice would be greatly appreciated.
thank you