Fast Idle stopped working

[Joesprocket]

mornin folks,

For whatever reason my fast idle hasn't been engaging and I'm looking for a way to adjust it. This is a Weber 32/36 with electric choke. The most recent work I've done was adjust the timing via the dizzy. When it ran correctly I would engagew the fast idle mechanism by tapping the gas pedal a few times, the car would start and jump right to about 2000 rpm and sit there until I kicked it down with a blip of the pedal. Now I engage the fast idle mech, it starts but can't get above 300-400 rpm on its own and the only way for me to warm the car up without it dying on its own is to manually hold the idle around 2K with my foot on the pedal for a minute or so before releasing and it'll idle on its own. 

 

I've found some good content on the subject but not sure where to start first. Do i start with the high idle screw first or by adjusting the mixture by rotating the circular plastic piece on the electric choke?

thanks for any and all.

[Guest zaeos]

Adjust the choke first so that it is almost closed, engine cold and outside temp at about 65f.

 

For engaging the fast idle you should only press the pedal once.

 

Here is what I found on setting the fast idle:

"Redline Weber Model DGV/DGEV Fast Idle Adjustment
With the engine warmed up and turned off, open the throttle and manually engage the choke plates (butterfilies). Release the throttle and then release the choke plates. The fast idle cam should now be activated and the fast idle speed screw should be positioned on the cam shoulder. Start the engine DO NOT DEPRESS THE THROTTLE PEDAL OR THE CHOKE WILL DISENGAGE. To adjust the fast idle speed screw "in" (clockwise) to increase speed and "out" (counterclockwise) to decrease the speed." 

 

This worked for me, setting the rpm to 14k when warm, however when i started the car cold the idle was only at about 1k so i screwed it in a little more and whaaa laaa!

Edited April 25, 2018 by zaeos

[TobyB]

Your choke might simply be stuck open.

 

Start with making sure all the linkage is free, 

and intact,

and I BET you find your high idle problem...

 

t

 

[worzella]

I am struggling with a similar issue, so here is my story and suggestions.

 

First, you have to remove your air cleaner and the cleaner base plate in order to have any chance of seeing the fast idle cam and screw and linkage. But be careful removing the 4 bolts and wave washers since it is too easy to drop one of those down the carb into the intake manifold.

 

Next, is your carb old or new? Mine is brand new and the linkages are tight and aligned. But my old one was crusty and beat and the fast idle screw did not even come close to aligning with the cam edge. Personally, the 32/36 cam/screw design sucks. The cam edge should have a flat spot instead of just the edge for the screw to push on so these alignment issues don’t happen over time… but planned obsolescence is the name of the profit game!

 

I will try to add some pix of what I am talking about, but I did not have my laptop at home and using a Linux machine with foreign software, so I gave up trying to write a doc with embedded pix and words.

 

So, I swore I had my whole fast idle/choke set right and the first morning I set it, the car roared to life and I was thrilled. Roared at 3500 RPM, but I ran around and reduced the fast idle screw to 2000. After a minute, I punched the pedal and she settled to a sweet 800.

 

Next time I started her in the morning, I punched the pedal and turned the key and yuck…. Barely started.. certainly not on fast idle and I sat there for two minutes holding the gas pedal down.. pissed and wondering why. Still not sure, but I am trying to think my way through this and I believe it has to do with my ambient temp (about 60 F) and how I had my choke coil body adjusted…. More on that later.

 

But here is my understanding of how things work/interact…

 

The electric choke is a wound coil of metal that reacts to a current. When it is cold, (no current and not a 100 degree day in Miami) it tightens and rotates a connected shaft counterclockwise, and when it warms up, it rotates the connected shaft clockwise.

 

The “adjustment” of loosening the three ring screws allows you to rotate the spring body counter or clock wise to set the tension that the wound spring applies to the shaft.

 

So what does this attached shaft connect to and what does it do? It does two things:

 

1) It is connected to a linkage that opens and closes the butterflies over the barrels. So when the coil of metal is cold, the force is counterclockwise on the shaft and the butterflies are closed…. What you want on a cold day! When the coil heats up and rotates clockwise, it causes the butterflies to open.

 

2) The other thing the shaft does is control the position of the fast idle cam. When you “punch” the gas pedal once to set the fast idle cam, this moves the fast idle screw out of the way and the tension on the shaft from the choke coil causes the cam to rotate into place. By “rotate into place” I mean that the high point of the cam is ready to contact the fast idle screw. When you let go of the gas pedal, the fast idle screw moves back into place, but now it is sitting on the high part of the cam.

 

Sitting on the high part causes the idle linkage to act as if you had the accelerator held down to about 2000 RPM, the suggested fast idle level. This level is set by adjusting the fast idle screw in or out to get to about 2K.

 

Now when you start the car, it should roar to life at 2000 RPM... held that way by the fast idle screw/cam, not by you holding down the gas pedal and bitching under your breath "What the fuck!".

 

So based on 2) above, the setup of the choke coil (how it is rotated when the 3 screws are tightened) affects how the fast idle cam rotates when you punch the pedal. Too much clockwise tension and the fast idle cam will not be able to rotate so that the screw stops on the high point when you let go of the pedal.

 

But too much counter clockwise tension and when you punch the pedal after a minute or so to let the cam rotate to the normal low point, it will take too long for the butterflies to open (item 1), if they open fully at all.

 

The cam actually has three positions….when you punch the gas pedal once to set the choke cam, it should sit on the highest portion of the cam (2K RPM). Then after a short time, you should be able to slightly touch the gas pedal to make the fast idle screw drop to the next level of the cam. Not sure what it drops to, but maybe 1200 RPM. Then when you fully pop the gas pedal after a minute or so, the cam rotates so it is not affecting the accelerator linkage and your RPM should drop to the amount set by your normal idle screw.

 

I think my problem is that I have the choke body rotated too far in one direction such that when it is slightly warm, the fast idle cam is not allowed to rotate for the fast idle screw to sit on the high point. Hence, when I start the car, the accelerator linkage is not juiced to 2K RPM, but rather is sitting in the normal 800 regular idle position and sits there and bogs and chokes till I give the gas pedal some push and hold it.

 

I hope to debug this this weekend, but it is hassle because the "initial condition" of cold morning happens only once, so I have to plan my investigation well

 

Randy 

 

 

 

 

[Joesprocket]

19 hours ago, worzella said:

I hope to debug this this weekend, but it is hassle because the "initial condition" of cold morning happens only once, so I have to plan my investigation well

 

Randy 

 

 

Thanks Randy! Really appreciate you taking the time to walk me through your own experience and plan. I'm going to follow suit the best I'm able to.

 

[Joesprocket]

oh! @worzella and if you have pictures to add that would be incredibly advantageous to all of us working through this.

['76mintgrün'02]

this thread was about water choke problems, but there is some overlap and it contains some photos that you might find useful.

 

 

[worzella]

OK - not the best photos, but I will start here.

 

This shows the rotating shaft I mentioned, the thing with the pin coming out toward you. Not sure what the horizontal sliding half-rod is..

 

 

 

This shows the heat sensitive coil. The loop at the end goes over this pin I mentioned that is connected to the shaft.

 

 

 

This shows when the metal coil has been heated and the pin/shaft rotates clockwise... and you see the butterflies open

 

 

This example shows if the metal coil was cold and moving counter clockwise causing the pin/shaft to rotate to close the butterflies.

 

 

Now, a lot of the doc mentions "marks" to align. I *think* the slit mark on the body is obvious... but I never read what is supposed ot line up with it. Last night when I posted I set the choke cover as such with the left edge of the metal piece to roughly align with the body slit. When I came home tonight to add my pictures, I took the carb sitting on the table and simulated a pop of the gas pedal on the linkage and sure enough, the high idle cam jumped into place where expected. So.... I am going to try this position like the picture below on Sat when I get to my car. I think that is a good starting point to set up the choke and tighten down the 3 screws on the ring.

 

 

So here are the exciting photos, ha ha ... this shows the fast idle screw up on the highest of the cam positions after I simulated a "blip" of the gas pedal. A couple things to see in this pix:

 

1) As I mentioned, this old carb is loosey-goosey and you can see how the fast idle screw is not aligned with the cam edge, but rather drifting to the left.

2) Note the HIGHEST of the three cam settings.. just a small edge of the cam about the diameter of the screw head itself. If the screw was aligned properly, it would sit on this tiny bump in the top of the cam. The next level of the cam is the long edge, about the length of the set of threads showing.. maybe a bit more. Hope this makes sense. And when you finally, tap the accelerator after about a minute to totally get off of fast idle, you see the sharp drop to the cam edge that is at the same diameter of the housing ... and not affecting the linkage at all.

 

 

When you blip that pedal the first time and set the cam to high point for fast idle, this is what your regular idle screw/stop looks like You can imagine/see that this looks like you had the accelerator engaged and about 2000 RPM. As it sits in fast idle, you can turn that fast idle screw (not this regular idle screw) to raise or lower the fast idle as desired

 

 

 

Please ask me questions if needed since it helps me figure things out too.

 

Randy 

 

 

[worzella]

Hey Joe. Where you going with that choke in your hand?

 

?

 

How did your fast idle weekend tuning go?

 

I started with plastic adjuster metal dge line up to body mark... did not set idle properly

 

Moved it clockwise to about 1:30 ish and set fast idle well but butterflies never opened fully even when hot

 

Bumped it a bit more right to 2:17 oclock (ha ha) and that was the sweet spot. Fast idle set properly and butterflies fully open when hot

 

Good luck and let us know whats up

 

Randy