Idle adjust on 34 PICT-3 FAQ

[llamas1]

I have had a hell of a time getting this thing to Idle correctly.
The bus runs great while you're giving it gas but when you let off the gas it will die. I have to rev the engine while im at stop lights. I have read the instructions several times in my Bentley book and followed the steps exactly. The fuel mixture screw and the idle speed screw do absolutely nothing. I just need to run up the idle a little bit so it wont die. I know on this model of the carb you're not supposed to adjust the idle by the fast idle cam and screw but that's what im going to try.

My question is does it matter which lobe of the cam you run the screw into? More specifically if I put the screw on one of the higher lobes will it stay there? One other bit of info that might be a clue. The bus will start and idle until the engine warms up and the choke opens up and the engine dies.

This carb is only a few months old. I guess I bought a lemon.

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Diagrams

Adjustment
http://www.volkzbitz.com/

Lit

Pix

[keifernet]

DON'T DO IT!!!!! running the screw up on the fast idle cam is a mistake... the thing will rich as shit... it will not likely solve your trouble

have you made sure the electric idle cutoff is actually functioning?

Try taking out the " stationary idle pilot jet" ( brass screw in jet) on the right side of the carb just behind below the choke and see if there is a small piece of debris in the tiny hole in the end of it. tap it on a mirror or a lean piece of paper on the work bench.

also is this a new or rebuilt carb?

At some point ( if it is used or rebuilt) somone could have " overtightened this jet" in the body of the carb and it will not idle worth a damn. after making sure it is not blocked... loosen it up a tad and run the engine... then turn it in and out ever so slightly... you may find a ' sweet spot ' where it runs much better and idle up high... if so then get some locktite and put it on the threads and set it to that spot and let the locktite set- up... then reaadjust the mixture etc. all over again.

[llamas1]

This the idle pilot jet you're speaking of?
Yes, it is a rebuilt carb. And I have no idea if the electronic choke works.
I will try cleaning it up and see what happens.

[Deaffy]

[jeremysmithatshawdotca]

Yes, I agree, pull it off get a kit, and rebuild it. The adjusting screws will get overridden by dirt or crap in the carb. You'll be amazed at the difference. Make sure you use compressed air and cleaner to really get the gunk out of all the passages, or you could have the same problem a few weeks down the road! Jeremy

[llamas1]

Just curious, what is the big No-No about setting idle by the fast idle cam?

The name itslelf implies thats what it's for.

[keifernet]

the way the 34 pict 3 carb is designed ( and the 30- pict 3 and 30/31 brosol replacment carbs too) the throttle plate " butterfly" is supposed to be closed warm at idle... this is opposite of how all previous versions of the VW Solex carb were.

It has to do with the idle circuitry being controlled/run by air volume hench the need to adjust the idle speed by using the big brass air volume control screw.

to overide the set- up using the fast ilde cam/ throttle arm screw is not going to resolve any idling issues... it may make the engine idle... but is not addressing the problem or problems that are the true cause.

and yes in your second picture the brass removable jet in the center of the pic is the staionary idle pilot jet... if it gets clogged the car will not idle. and if it has been overtightened at some point then it needs to be loosened just to point that the engine clears and idles up then locktite applied to keep it there.

[Amskeptic]

[llamas1]

Should the fast idle cam change positions with the choke/butterfly?

Just trying to educate myself on carbs?

[keifernet]

Yes, and since you say your not sure your choke is working, or not adjusted right that could be a part of your problem.

first, I'm sure you at least have the wire from the 12V+ side of the coil attatched to the electromagnectic cutoff solenoid and then over to the choke.


With the engine COLD first thing in the AM

loosen the three screws on the choke hold down collar and rotate it counterclockwise till the butterfly (and the choke cam) moves nearly shut.
then the set screw will be on the upper notch of the fast ldle cam...

( open the throttle a bit to keep the screw on the throttle arm dis-engauged) until you set the choke

You should see a " dot" or a line scribed on the choke element housing
and then a few lines cast into the choke housing on the carb top.
these marks are a general referrence and sometimes ( mostly in the summer ) you have to go past them to get the choke to do it's job

It is important to remember to re-set the choke several times a year as the weather/ seasons change. ( the bi-metallic spring inside the choke element reacts to the ambiant temperature and the choke sets accordingly)

if the choke is set for summer setting the first cold morning it will be closed up tighter than a bulls ass in fly season, so back off it a bit or the engine will chug and run rich too long for cooler weather warmup.

vise versa for warm weather... if the element is not set tight enough the choke will not stay on long enough for the manifold to warm by the pre heater tubes and the engine will die the first few stops down the road.

Here in Houston ( and other Southern Cities/ climates) you have to almost re -set it in between every cold front/ snap/ warmup just to keep the engine starting and running smooth and easy in the AM and later in the day after work.

Sorry this got so long but it pretty much sums up the choke deal...!

[llamas1]

Thanks Keith,

I believe that would be my problem or one of them. There is no difference
in the cam from startup to after being run for hours. I believe the choke is always closed. That would explain the backfiring. I do have the choke and solenoid hooked up to the coil but have never verified with voltmeter that the choke is actually getting 12+.

It's probably just way out of adjust.

[keifernet]

I presume you mean the choke is not on ? meaning the cam never moves and the fast idle screw never touches the other notches on the cam?

try loosening the screws on the choke an adjusting it like I said in the other post. If you rotate the choke element and the cam does not move, then the spring did not "catch the lever" when the carb was re assembled after being rebuilt. you would need to take the choke off and line it up right/ start over
or the rebuilder may have just set the choke in a "neutral" position


then the engine should start and run/ idle high for at least 2 - 3 minutes.
and after "blipping" the throttle a few times it should settle out and the choke should be fully open and the screw not touching or just barely touching the last notch on the cam

then feel the element it should be warm to the touch if it is working.

If it is cold and it does not go off then the elelment may be bad.

[Nighttrain1974]

I had pretty much the same problem with my bus, the cutting out at lights and everything. I took my bus into my mechanic who replaced my condenser and also set my timing and points to the right places. Invaluble stuff. Also don't touch the fast isle screw at the top of the carb, i tried that as well and it ran like absoloute crap.

Best solution i found was open the big screw up 2.50 - 3.00 turns from all the way in and then adjust your idle with the smaller screw on the side of the carb till you get a nice 900 - 1000 rpm idle. Then if it still wants to die at the lights i just up the little screw a touch and bingo, no problems. Also your choke element, take the bloody thing out and test the element, easy to do. Boil your kettleup and pour some nice hot water on it and the element should expand, blow on it after that and it should contract.

Sorry to waffle on folks, but the biggest thing by far what helped my idling situation was new plugs and leads.
_________________
72' beetle (stock)
72' beetle (cal-look)
71' bay (now sold)

Everything rests in peace until man forces it to do otherwise.

[Amskeptic]

[boardfu]

Sorry to bring an old post from the dead, but I need to. Besides Ive so far found it very useful. I knew about the electronic choke, but not the other electical solenoid on the other side.

My car wasnt idling. Id have to rev it to keep it alive. Pain in the ass. Anyhow, I had the electronic choke(on the right side, the side without the hammer looking thing) hooked up the the + of the coil...but it still died....

Then I found out by reading this post, that its actually the solenoid on the other side of the carb that is supposed to be hooked up to the + side of the coil....

Heres where im confused.....

Where do I plug in the electonic choke?

Someone said in this post:

"First, I'm sure you at least have the wire from the 12V+ side of the coil attatched to the electromagnectic cutoff solenoid and then over to the choke. "

How do you go about this?
Thanks,
John

[nemobuscaptain]

Holy technical answers, Batman!!!! I'm going to have to re-read this when I've had some rest.

[keifernet]

[orangekoi]

[jashley]

Alright, I just rebuilt my carb, and the ol' girl runs a *lot* better. I'm having trouble getting the idle set properly, though. This thread looks like a good place to fish for advice.

The directions say to bottom out the little screw (volume control) and then back it off 2.5 to 3 turns. Then set the big screw to 900 RPM. Then back out the little screw until RPMs max out. Then use the big screw again to return the idle to 900 RPM.

Fine, but I can't find where the little screw bottoms out. The o-ring on the screw makes turning it in and out tight, and I'm afraid to keep on turning. How do I know when I'm at the bottom?

Also, can anybody explain why in some settings of the two screws, my car alternates idling at high and low RPMs?

Thanks!

[jashley]

I just didn't turn far enough. It was tight with the O-ring, but it definitely stopped at the bottom and didn't want to go further.

I was generally having trouble setting the idle. Turns out I had not plugged a vaccum port on the manifold. More information at http://www.ashleyfamily.org/mike/1125/

Mike