LUVTruck.com

So i bought a rebuilt stock carb for my 80 Luv 4x4 (Before you guys say buy a Weber, I'm in CA and stock with the smog rules).
I did a search in stock trucks, but couldn't find info on setting the the idle and mixture screws. If I can get into the close to where it has to be set, it will make things a lot easier.

I'm thinking I might have to adjust the automatic choke as well.
If anyone has some info on this, it be appreciated. =)

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

Awhile back, I did remember reading on one post that you could turn on of the screws all the way in, and back out so many turns, but I can't find that post.

As a starting point, screw in the MIXTURE until till it stops (gently, don't force it) back out 2 and 1/2 turns for a starting point. With the engine at normal operating temperature adjust the idle SPEED screw to 900 rpm. Slowly turn the MIXTURE screw in or out for the maximum idle speed. If the idle speed increases adjust the SPEED screw back to 900 rpm again. Keep going back and forth between the two until you find the best idle at 900 rpm.
Next slowly turn in the idle MIXTURE screw untill the speed just starts to drop a bit (about 40-50 rpm) and you are done. Should pass emissions fine there. Going from memory, used to do many of them.

I got it close to idling at 900rpm, and its running a little rich. Though your instructions helped out a lot.
Down the road, I'd like to build a pre-smog Luv.

Thanks for you help Egg!

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

After I adjusted my idle and mixture screw, it was running decent.

I drove it for awhile, and then it did not want to idle without keeping the throttle gas pressed. I found one of the wires off the plunger on the gas pedal came loose. The female plug (still connected) goes to a light green - yellow stripe wire. The male plug is the one I found unplugged. The closet wire to it is a black-white stripe wire. The only other choice is a brown wire, but I'm pretty sure that goes to my heater controls. I think I'm also going to see if any of the vacuum hoses came loose.

So I hooked the green wire off the plunger on the gas pedal to the black wire white strip. The electronic choke works ok, and it starts up. Shortly after the choke shots off it doesn't want to stay running. I tried adjusting the mixture screw, but it doesn't seem to help. I've also used a small screw drive to prop the gas pedal slightly depressed so I could adjust the mixture screw while it ran. Still the same problem.

Note: I put in 2 new fuel filters (one's right before the carb), and put in new gas from a 76 station, all of this before putting on my rebuilt carb. So I don't think its a problem with the fuel or fuel lines/hoses. The reason why I got a rebuilt carb, is the old one the secondary was working right.

The wires on the gas pedal operate the coasting richer solenoid on the carb. Should not affect anything on the idle--strickly an emission control device. However if the "run on solenoid" does not have power it will not idle, have you checked this? A round cylinder device at the base of the carb, pointing towards the firewall and having a single wire coming from it, (maybe red). This needs to show 12 volts when the key is on.
If this is the case and you repair it, you will have to go through the MIXTURE and SPEED adjustments again but it will then idle properly.

I believe this in the solenoid and wire you are talking about, right? It looks like it connects to the base of the control for the electronic choke.

That is correct. When power is applied ( key on ) the plunger pulls back opening the idle port in the carb. Key off, a spring pushes the plunger back out closing the idle port, thus preventing "dieseling". It and the choke gets its power when the key is on. Solenoid unscrews to remove to check, has a tappored needle and a gasket involved.
While out, a good time to squirt some carb/choke cleaner into the port to clean out any residue that was missed in the idle circuit during refurbish/cleaning. Solenoid could be failed/open circuit but is rare.

I took out the solenoid and sprayed inside. No change there (but still good suggestion). I finally got a meter and I measured the power source to the solenoid. I'm getting 13 volts. I would think that be enough to power it, right?

So I was thinking I still have my old carb (that's going to be eventually shiiped as the core), and I could swap the solenoid with rebuild one. I know the old carb did not have that problem I have now.

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

Yes 12-14 volts fine. Good idea swapping out the solenoid with the other one. Also can check operation by removing the solenoid, connect up the wire again, turn on the ignition and touch the body against carb completing the circuit. It may click and the needle retract and extend a bit each time.
Another thing you can try before you give up....remove the idle adjustment screw and squirt some carb cleaner spray in there. May dislodge a piece of dirt that got in the idle circuit. I use a carb spray can with the long plastic nozzel and hold it in there to force it through the passages. Count the turns from seated before removal to get it back in the same place.
It sounds like something changed after you got it adjusted correctly. My guess is maybe a piece of dirt got into the idle passage----or--bad solenoid is my other guess.

I pulled the idle screw out and sprayed carb cleaner can with straw into the opening. After I put the idle screw back in, it actually started to idle (after the chock went off). I then moved my truck a few feet forward in the driveway, and it went back to not idling anymore. I pulled the idle screw out again, and did more spraying. Same results. Runs good, and then when I go to drive it, it won't idle.

Before I put the rebuilt carb on, I put in a new fuel filter by the gas tank, and a secondary filter by the carb. I'd think with 2 filters, that be a lower chance of debris going through. I'm a bit stumped what do do next.

I guess at this point I would take off the float bowl cover w/sight glass, and look carefully for any residue in the float bowl, specificly around the metering jet/s in the bottom of the bowel. Seems like dirt symtoms but maybe not, might eliminate that as the problem. Also check float level, should be in the center of the window.
Worse case I would reinstall the old carb to see if it fixes the idle. That would nail it down to that carb or not.
Your filtering seems ok.

On edit: I would also disconnect the wire from the throttle plunger you previously mentioned---just to eliminate that "emission control device" causing a problem.

I ended up taking my truck into my mechanic. He swapped the run on solenoid, checked the float and fuel circuit (where the fuel runs from float bowl). and cleaned that out, He then swapped fuel Assybely pump (Cylinder like part that's part of the linkage is hooked up to). Runs a lot better.

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

Thanks for posting the results. Sounds like we almost had it cornered for the problem. Should not have had all these problems with a replacement unit however.

I know you have got it taken care of already but somewhere on here I remember reading how a member in CA swapped to a weber and then adapted the stock air cleaner to sit on it to make it look like it was still stock.. and went back to the weber air cleaner after emissions testing. just saying

glad you got it handled tho, have you got it thru emissions yet?

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Luvless
1980 Mikado-Sold.

1993 Lexus SC400 my Daily
2004 Yamaha WR250F my new love in life
2016 Toyota Camry my girls ride

I have thought about Weber. Most use the 32/36 model. I just got my truck smogged today and it passed. If I put a weber on there, does it have similar lines for the vacuum lines? I only ask if it would pass smog inspection. Maybe a CA Luv owner can let us know.

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".