74 Datsun 620 Idle help please

[AlexDeLarge]

Really need some input here guys as this is my only ride and dont want to keep getting rides to work.

Ive got the stock Hitachi carb that has been fitted with a manual choke and have been driving it with no issues

the past 8 months. I only drive it 5 days a week roundtrip of 8 miles a day and I get to work at 4:00am and leave

at 3pm so it sits in the lot for 10hrs before I bring it home. Anyways, in the mornings I set the choke for about 2 or 3 minutes(

still kind of warm here) then I push in the choke and it revs up a little and then once the temp gauge gets up to the first line I will

hear a audible click (kind of springy click like a relay,idk) then I give it a little gas and it idles down and Im good to go. Ive been doing this the past 8 months.

Yesterday, when I went to leave work I forgot to set the choke and tried to crank it, it wouldn't start so I just set the choke like I always do for a couple of minutes

and then took the choke off and it revved up a little like always, but once it warmed up enough on the temp gauge I never heard the click like I usually do and 

although the truck was warmed up it would not idle, just die. I kept trying, but nothing. I ended up getting it home but when I would come to a stop in neutral it would

just die. When I got home I pulled the fuel filter and it was clean, blew some compressed air through it and back through the gas line with the tank vented and it is

all clear, this didn't help. Fuel filter has gas in it and carb bowl has gas and looks clean. tested the wire on the idle cut solenoid and it is hot, it clicks as it should when ignition is switched on/off, but this is not the springy click I usually hear when warming the truck up. Looking from the front of the carb there is one more wire to the left of the idle cut solenoid wire, its red/black has power also. A friend of mine came over after work and messed with one of the idle screws (phillips head to the left of the flathead) and got it to idle but its a little rough. I backed out and stopped in neutral and it continued to run then I took it up the road and pulled over and when I came to a stop in neutral it died. Started it back up and went in reverse stopped and it idled then I got it home and as I slowed to  park it died again. My friend seems to think I got a hold of some bad gas and I need to run seafoam through it with some 100% gas. I seem to think that something isn't working because I did not hear that "springy click" on warm up. Anybody know what that click is I am hearing on warm-up. Remember this was originally a electric choke stock carb that was not working correctly that was fitted with a manual choke. The idle cut solenoid is wired up and has power and there is another wire over to the left hand rearside of carb (looking from front of engine bay) that has power also. Is it possible for the idle cut solenoid to go bad although it has power and clicks with the key switched on/off. Any ideas or help is greatly appreciated, this just happened out of the blue.

[AlexDeLarge]

I forgot to add that a couple of times a week lately when I get it home it will diesel for a couple seconds after I shut it off.

[datzenmike]

If we assume the idle cut solenoid is working properly, then the only other cause of gas getting into the engine causing dieseling when the engine is shut down is

1/ The choke is on or partly on.

2/The carb is flooding for some reason.

3/ The BCDD is activated or never shut off when last used.

 

For 1/ and 2/ ....Next time it acts up take the air filter off and look at the choke or the glass on the front of the fuel bowl. Is it at the line or is it over filled?

 

3/... can you post a picture of the left side of the carb. the side closest the fender?

[AlexDeLarge]

I will get a picture up tommorrow...late here. I unscrewed the idle cut solenoid earlier and it is indeed working. The needle goes in and out. I put it back in without the needle and made no difference. ..still doesnt want to idle....something is wrong somewhere.

[datzenmike]

With the idle cut solenoid removed, stick the red straw from a can of WD-40 or carb cleaner in the hole and blast it. Unscrew the idle mixture screw, but count the turns so you can put it back the same. Spray the carb cleaner into the idle cut hole... it should spray out the idle mix screw hole. Try reversing this and spray in the idle mix screw hole. Re assemble and try it.

 

Someone messed with your idle mix screw. If there was blockage of the idle circuit and this is now been cleared by spraying, the mixture could be anywhere. If it does not idle, turn the idle speed screw up until it does. Now lower it as close to stalling as you can. Turn the idle mixture screw out slowly expecting the idle to suddenly increase. Lower the idle speed. Adjust the mix screw in or out to get the highest strong idle. Lower the idle speed again and adjust the mix screw in and out looking for the best smooth idle. Keep doing until you cannot improve the idle quality and the idle speed is around 700.

 

If you can get it to run and idle start fine tuning the mixture by turning the mix screw in and out looking for the strongest idle. Turn idle speed down and repeat the mixture adjustment. Idle will have gone up so turn it down and keep repeating until you cannot improve the idle quality and the idle speed is around 700.

[AlexDeLarge]

Ok, cleaned the idle cut sol. port and removed idle mixture screw and blasted a bunch of wd40 through both holes and then blew some compressed air through it until I made sure it was clear. I put everything back, got in choked it and after a minute or so I heard the "springy click" sound and took the choke off. It idled up and when it got to temp I gave it some gas and it continued to idle high. I adjusted the idle speed screw and got it fo idle down. I tried to do what you said but I kept backing that screw out and never could get it to "almost stall". I was afraid I was going to back it all the way out. I turned it back up, then down again and turned the idle mixture and got a good idle. I took it up the road and everything was fine. When I stopped it didnt die, but felt like it maybe could for a second. Let it sit while I ate dinner and decided to go get some 100% gas. Sat in traffic both ways and couldnt even hear it idle. Pulled in the driveway came to a stop and it died, started it back up, pulled up and stopped and it didnt die, sat there and idled. Sounded like the idle was too low compared to where I had it before all this happened so I got out and adjusted the idle back up a bit. Im going to drive it to work in the morning and see how it goes.

[datzenmike]

OK lets revisit the idle mixture again. Turning the mixture screw in reduces (leans) the fuel to the idle circuit, turning it out makes it richer. Engine must be warmed up before setting this and the choke off. Idle must be low enough that it is running on the idle circuit and not running on the primary barrel.

 

Now with idle, say, below 900 preferably, turn the idle mix screw in or out looking for the fastest smooth idle. Turn slowly and in 1/4 turns so the engine has time to respond. Presumably, the idle speed has gone up as you get closer to the ideal mixture. Turn it back down with the idle speed screw and repeat the mix adjustment. When you can't improve the idle quality and the idle speed is around 700 you're there.

[banzai510(hainz)]

need to do all this as stated above  and time it with a light