Electric choke lead on a Weber 32/36- current questions.

[720inOlyWa]

85 720 truck, Z24 motor with a 32/36 Weber.

 

I think that my choke is not working properly. No, I know it isn‘t working properly. She is very cold blooded and the choke only seems to work (nominally, temporarily) if I douche everything related to the choke with carb/choke cleaner. Three days later, the choke is not working again. Yes, I have taken it ll apart and cleaned everything thoroughly, looking for binding, friction, etc. I suspect that it is not getting current- or the right amount of current-  to the choke connector itself. I am about to rig up a ‘bulb and wire’ tester to go find out, but I am pretty sure I am right.

 

Now, when I installed the Weber, you can bet that I hooked it up to the blue wire lead coming out of the carb harness plug and that I made damn sure my connections were tight and right, as instructed. So that aint it.

 

What I wonder is  two things: how much juice should be going to the choke lead anyway, and, if it is a dead lead,  can I grab any hot lead coming out of that carb wiring connector and use that instead? Is the juice to the choke variable, less than 12 volts, or ‘conditioned’ in any way? I can’t seem to find this information.

 

Thanks!

[Doctor510]

85 720 truck, Z24 motor with a 32/36 Weber.

 

I think that my choke is not working properly. No, I know it isn‘t working properly. She is very cold blooded and the choke only seems to work (nominally, temporarily) if I douche everything related to the choke with carb/choke cleaner. Three days later, the choke is not working again. Yes, I have taken it ll apart and cleaned everything thoroughly, looking for binding, friction, etc. I suspect that it is not getting current- or the right amount of current-  to the choke connector itself. I am about to rig up a ‘bulb and wire’ tester to go find out, but I am pretty sure I am right.

 

Now, when I installed the Weber, you can bet that I hooked it up to the blue wire lead coming out of the carb harness plug and that I made damn sure my connections were tight and right, as instructed. So that aint it.

 

What I wonder is  two things: how much juice should be going to the choke lead anyway, and, if it is a dead lead,  can I grab any hot lead coming out of that carb wiring connector and use that instead? Is the juice to the choke variable, less than 12 volts, or ‘conditioned’ in any way? I can’t seem to find this information.

 

Thanks!

Just find a SWITCHED 12V source, in other words, hot ONLY when you turn the ign switch ON.

[bananahamuck]

 it is 12 volt but i don't know if it is a switched 12volts or not on your 86...( meaning turns off after truck has been running for awhile) . Pretty sure the truck will have to be running to check it though. Key on engine off i don't think it will have full voltage.,

 

We used silicon spray on the linkage (  assume WD40 would work) and leaned the choke out a bit when the stupid choke was binding up and that seemed to help.

 

(edit) i hate Webers

[720inOlyWa]

Of course...  THANKS!

[datzenmike]

It is only 'hot' when the engine running and alternator charging. If worried about it just wire it to the Red idle cut solenoid beside it which is 'hot' any time the ignition is on.

 

When the engine is cold take top off air filter and look. Pump gas pedal. You should see the choke snap shut. Start engine. In about 8 min the choke should be completely open.

[720inOlyWa]

Well, the mystery continues... and so does the bafflin’!

I looked at  my choke butterfly with the engine of ignition on, and everything dead cold. The butterfly was wide open, with the ignition on. Switching to the red lead did nothing to ‘snap the butterfly shut’. A direct 12 volts off of the battery had no effect either. So I reasoned that perhaps I had grossly misadjusted the choke setting and loosened and reset the choke tension so that it was closed at cold, and I started the truck. Eight minutes later, the butterfly was still 85% closed and showed no real inclination to ease open with the engine temp. Pulling the lead to the choke had no effect whatsoever. Oh sure, you can step on the gas  and it flops open, but it immediately goes right back to 85% closed and pretty much stays there.

 

Maybe it changes at 10 minutes and I was impatient. I dunno. But I will leave it this way for today and do some experimenting with the 4x4 setup to see if I can learn something from it that I can apply here. (It is the same exact setup) 

 

From what I can gather, the choke operates by having a bi-metal spring which expands and contracts with the temperature to open or close the choke appropriately. What the electric lead is doing to facilitate this action is beyond me. Looking inside, the juice just terminates inside the choke coil cover, but what is it driving? For now, I still I don’t quite get it.

[bananahamuck]

The choke is held shut-ish by cold spring tension ,, when it heats up it expands and rotates the linkage to open.. Is that what your asking?

[Doctor510]

Well, the mystery continues... and so does the bafflin’!

I looked at  my choke butterfly with the engine of ignition on, and everything dead cold. The butterfly was wide open, with the ignition on. Switching to the red lead did nothing to ‘snap the butterfly shut’. A direct 12 volts off of the battery had no effect either. So I reasoned that perhaps I had grossly misadjusted the choke setting and loosened and reset the choke tension so that it was closed at cold, and I started the truck. Eight minutes later, the butterfly was still 85% closed and showed no real inclination to ease open with the engine temp. Pulling the lead to the choke had no effect whatsoever. Oh sure, you can step on the gas  and it flops open, but it immediately goes right back to 85% closed and pretty much stays there.

 

Maybe it changes at 10 minutes and I was impatient. I dunno. But I will leave it this way for today and do some experimenting with the 4x4 setup to see if I can learn something from it that I can apply here. (It is the same exact setup) 

 

From what I can gather, the choke operates by having a bi-metal spring which expands and contracts with the temperature to open or close the choke appropriately. What the electric lead is doing to facilitate this action is beyond me. Looking inside, the juice just terminates inside the choke coil cover, but what is it driving? For now, I still I don’t quite get it.

 

OK here;s the deal:  just giving the choke a shot of  +12v power will NOT cause it to snap shut.  Pump the throttle once and it will.  Now it's closed, start the motor and as it warms up, the choke plate will open, after a few minutes hit the throttle again and it should open all the way.  It's not rocket science.   You may still have to adjust it a bit in its cold setting, NOT slammed shut, just closed.

[datzenmike]

No one said that 12 volts would  make the choke 'snap shut'.

 

It is only 'hot' when the engine running and alternator charging. If worried about it just wire it to the Red idle cut solenoid beside it which is 'hot' any time the ignition is on.

 

When the engine is cold take top off air filter and look. Pump gas pedal. You should see the choke snap shut. Start engine. In about 8 min the choke should be completely open.

 

 

The choke is a bi-metallic strip with two dissimilar metals that expand and contract at different rates with temperature. When cold the coil contracts, when warmed up it unwinds. This feature is used to open and close the choke lever.

 

In the choke housing is an electric heater. This is what warms the coil making it unwind and open the choke. They are designed to take about 8-10 minutes or so and are timed to roughly imitate the time it takes the engine to warm up. The heater stays on at all time the engine is running to keep the choke open.

 

When the engine is shut off everything begins to cool down and when fully cold the coil is contracted and trying to close the choke. It can't fully close because the throttle is in the way. This is why you step on the gas just before starting a carburetor engine that is cold. Stepping on the gas releases the choke and it then snaps shut.

[720inOlyWa]

Ahhh- hah! So now I get it. I guess the little 8 minute heater in there isnt happening for some reason because clearly, the coil is not changing the butterfly at all, at any time. Yeah, the little post is in the spring correctly. It just isn‘t working. I am going to replace this (used) carb with the brand new one that I put on the 4x4. It seemed to be working fine. Then, I will fiddle with this one until I figure it out. (I‘m too cheap to give upon it!) I think it may have more than just a ‘choke isnt working’ issue.

 

As I was going through the points of this thread yesterday, I was running the truck with the air cleaner off. I started messing around with the linkage that drives the second barrel of this 2 barrel carb. (the barrel closest to the head). It never seems to open as the gas pedal is depressed. And the linkage to it seemed very sticky to me, like it hasn‘t worked in a while. Does this butterfly only open under load? On the 38, they are both driven by the meshed gears, but I don’t see an obvious drive mechanism for the second barrel on the 32/36.

 

Addendum: The second barrel was sticking, but I loosed it up and now see how it is driven. 

 

Post addendum: well, this thread is done. I swapped out the used Weber for the new one and it behaves exactly like it should. Cold, you pump the pedal once and it is nicely shut. As it warms up, it opens to about 75% as it warms and easily snaps open all the way when hot and you give it some revs.

 

Which brought me back to the carb I removed. I hooked it up again, right there laying on the intake manifold and the choke did not respond when plugged in and grounded. Also, the secondary barrel linkage is clearly not working right. It has a real bind point, just as the linkage comes on. This carb has some problems. It also looks a lot funkier than the one I ordered directly from Redline. I wonder if it is one of those knock off Webers that I have been hearing about.

 

I found a really link here somewhere in the forums on fine tuning the Weber. After a really nice test drive, I am ready to go through the carb tuning process to dial it in. 

 

Thanks for all the help!