‘84 Funky Idle

[906-Runner]

So I did a little looking up on these forums but couldn’t really find a definitive answer to my problem.

 

So two weeks ago the remanufactured alternator I got crapped out on me. Just today I got around to putting the replacement in and getting it running. After sitting that long I expected it to not start easily and the carb needed cleaning anyway cause one barrel was all black inside.

 

After I got it all cleaned up and back together I had to jump the battery using my wife’s car but it won’t stay running. It has a Weber carb with an electric choke that’s working, but I have to keep pumping the gas to keep the truck running and as soon as I let off the gas the idle gets choppy and then it dies.

 

I’m thinking it may be misfiring cause of the black soot in the carb but it ran good up until the alternator crapped out on me.

 

What sort of ideas do you guys have for me to get it back up to snuff so I can start daily driving this truck again?

[datzenmike]

Get a volt meter and check across the battery posts for just over 14v when running. Re manufactured anything these days is a crap shoot. You only have to look at the old one you have that failed you. They are shit. So likely the 'new' one could be 'bad in the box'. If not charging the engine is running on what little charge is in the battery from boosting it.

[906-Runner]

I did have the alternator tested before I even put it in the truck and verified it’s good. Even now it’s in the truck it’s reading like 14.3v with the engine running.

 

Would a bad alternator cause the idle to be choppy? It almost feels like a misfire cause of the way it sputters when I give it gas

[datzenmike]

You have a volt meter in the truck?

 

For now I'll assume the charging is ok. If the carburetor was black probably the choke was on more often that it was off. Clean the spark plugs or take for a long drive. Spark plugs are actually self cleaning but you have to drive long enough with the engine up to operating temperatures and the choke must be off. 

 

nest time the engine has been running for 15 min that the top off the air filter and look at the choke flap. Should be vertical or open lke this...

 

 

... and not part open and not closed...

 

[906-Runner]

Only one side of the carb was black. How would one go about making sure the choke is operating properly. The temperature here has dropped significantly since I tuned the carb so might that be my issue?

[datzenmike]

In cold weather gas is much slower to evaporate and gas will not burn until it vaporizes and mixes with the air. Normally the ATC (air temp control) provides warmed air from the hot exhaust and the intake and the cylinder head are warm and provide the heat needed to vaporize the fuel droplets. When cold a choke forces an over rich condition to maximize fuel evaporation. There will be a lot of fuel that cannot burn and this tends to collect as carbon on the insides of the combustion chamber. Black inside the carburetor is likely from a few backfires. 

 

The choke is only on the primary barrel. The choke is operated by a bi metallic spring that contracts when cold and pulls the choke flap closed. The spring is warmed by an electric heater which unwinds at a specific rate and coil expands and opens the choke as the engine warms up. The electric heater is on a relay and this requires a charging alternator to work properly*. If you had a charging problem the choke would have been on more than it should have and may have carboned up the plugs. Clean the spark plugs first and there should be an improvement.  

 

 

* The intent of the relay is to shut the heater off should the engine stall while you are indoors having a coffee while your truck warms up. Without the relay and a charging alternator the choke heater would continue to warm up (ignition still on) even though the engine is dead cold. When you come out you have a freezing cold engine that is very difficult to start because the choke is turned off.

[906-Runner]

So right off the bat I just got new plugs and wires cause a connector in one of the old wires was broken. Once those get installed I'll probably have to reset my choke to account for the cold weather correct? How would I go about doing that, same as I did when it was warm outside? 

[Stinky]

NO, not correct.  The spring reacts to the heat, or lack of and doesn't need any adjustment.

 

But, it does seem like ur choke is not working quite right.

[datzenmike]

2 hours ago, Stinky said:

NO, not correct.  The spring reacts to the heat, or lack of and doesn't need any adjustment.

 

But, it does seem like ur choke is not working quite right.

 

6 hours ago, datzenmike said:

 

 

The choke is only on the primary barrel. The choke is operated by a bi metallic spring that contracts when cold and pulls the choke flap closed. The spring is warmed by an electric heater which unwinds at a specific rate and coil expands and opens the choke as the engine warms up. The electric heater is on a relay and this requires a charging alternator to work properly*. If you had a charging problem the choke would have been on more than it should have and may have carboned up the plugs. Clean the spark plugs first and there should be an improvement.  

 

 

 

 

How is it not correct?

 

Newer ones are set at the factory and riveted in place so they can't be adjusted by the home mechanic, no matter how well intentioned, and can't cause poor emissions and bad mileage during warm up. Earlier ones were adjustable and marked rich or lean direction. Almost always I would have to turn them slightly richer in the middle of the winter for better starting and back down again in the spring.

[906-Runner]

Figured out why the idle was messed up. So I checked the plugs and wires and found a nick in two wires and two burnt plugs(intake side), so I replaced all the plugs as well as the wires. Figuring I’d solved the problem I started the truck and it ran a little better, it would just die really quick. Turns out a cap on a vacuum line hidden behind some stuff had cracked and then fallen off so it was pulling too much air in