OLDS Choke problems

[Ribbedroof]

Don't convert it to electric. It's pointless. Never understood why everybody's obsessed with always wanting to do that.... Just follow procedure in your manual. Whatever the issue is it will be a cheap fix.

Cleaner installation, no tube to rot away, easy to setup and maintain.

Not obsessed, just offering alternatives.

Figured (incorrectly) that like most people, didn't bother to own the service manual, wherein the answers to the question lie.

There are many answers to any question, it's up to each of us to decide what works best for US.

 

[69hurstolds]

Oh, where do you start? It appears something is very off on this. You shouldn't need any electrical test gear to check this. Just a vacuum pump and maybe a phillips or thin small flat blade screwdriver.

First, if it's an H/O carburetor (no different than any other Qjet as far as hot air Qjet chokes go) it will have 17084554 read vertically on the driver side of the carb near the rear. Any other number and it wasn't from an 84 H/O.

When the engine is cold, and you blip open the throttle to set the high idle/choke flap to closed, the engine gets a squirt of fuel, and when the engine cranks (in a perfect world, one pump would do it, although we all know it's not a perfect world) and starts, the primary choke pull-off will open the choke blade just a smidgen. This also keeps the secondary air flaps closed via linkage. The choke housing has a tiny little port in it which pulls air from the choke housing into the carb. This low pressure area in the choke housing allows "clean" air to flow through the tubing in the back of the carb, through the heater tube in the intake, and then up the little curved tube to allow the heated air to enter the port on the back of the choke housing. When the choke spring warms up via that hot air, it relaxes to allow the choke flap to open more and allows the weight on the fast idle cam to pull it down to "normal warm engine" idle. Which usually means you need to blip the throttle after it's warmed up to let that weight do its thing. Is the linkage hooked up for the choke flap? With the engine off, hold open the throttle slightly, and move the fast idle cam up and down and if the choke closes like it should. If the choke flap's flopping around and doesn't respond, the linkage could have slipped out somehow or was never put in correctly.

Unfortunately, the choke is preset and the housing cover riveted to the housing from the factory. There's a tang/slot on the housing and cover which aligns to position the choke housing to go on only one way. No way to adjust it the way it sits. It's usually replaced with a new choke cover unit and riveted in place. I've never done it, but I guess you could grind off the tang and use screws instead of rivets to adjust the cover if you had to. TBH, I've never had to replace a choke spring/cover unit because of failure.

Also, check when cold, hold open the throttle slightly and see if the choke flap snaps closed. Move the fast idle cam weight down and let go and see if it goes all the way closed. If not, there could be a lot of gunk holding something up.

With the engine running, is there a vacuum being pulled on the tube that attaches to the back of the carb? Pull it and see. If it's not, something may be plugged. Hard to imagine, but possible if no flow, the choke stove (U-tube) in the intake manifold has rusted through and exhaust/carbon may be plugging the tubes. It's a long shot, but...

Also, while the engine is off and if the choke flap is all the way closed, take a vacuum pump and pull a vacuum on the primary choke pull off. If it pulls the linkage forward and slightly opens the choke flap about 1/8" or so and holds, you're good. If it doesn't do squat when vacuum is applied, then the diaphragm's shot. If it pulls forward and holds, but doesn't open the flap at all, then you can use the adjustment screw to adjust the flap opening to about 1/8" cold choke position. The only way to fix it is to replace it if the diaphragm's shot. Normally, this type of problem exhibits itself as a monster-rich cold start condition because it's not opening the choke flap to allow a little air in. It strangles itself on gas and black exhaust smoke everywhere. Revving the engine until the choke starts to heat up usually gets you back in the normal operations again. Again, that's assuming everything else is fine.

I totally agree with DoubleV - if your hot air system isn't terribly corroded/leaky and is operational, there's absolutely no reason to change to an electric choke. Unless you want to. The choke either operates, or it does not.

Long pipe from back of carb to choke stove is GM p/n 419302. Short curved pipe from stove to choke housing is GM p/n 559344. The choke stove is GM p/n 412620 for SBO (a little different than the BBO). And the corresponding gasket is GM p/n 22547859.

Choke cover retainer rivet kit 17067078. Could have been had separately, but also came in ACDelco choke housing kits and some ACDelco carburetor rebuild kits.

Choke housing cover/spring is ACDelco 17110646 or equivalent aftermarket.

Primary choke pull off is ACDelco 17067211 or equivalent aftermarket.

Please correct me if I'm wrong.

 

[69hurstolds]

From that second picture, it seems a lot of things are still original to the car. Possibly that heater hose coded "AU" back there appears to be an original style. That's weird. But the water cut off valve in the intake is the original style. The AIR pump dump hose from the pump to the air cleaner has the original yellow stripe on it. And everything else SEEMS to be mostly original. Except the plug wires and some hoses. The choke housing clock position looks about right as well. The "GM" is roughly in the 5 o'clock position when looking straight on with the decal on the top.

I got a new 84 H/O carb in the garage here. The choke works perfectly and as you can see, it's the correct number 17084554, manufacture date of Wednesday, June 6, 1984. Which was way after the H/O run, so this would make it a "replacement" carburetor. To note, the factory carburetors for the 85 442 was a restamped 84 H/O carburetor made in that same general time frame it seems. They simply stamped a "5" over the first "4" in the carb number. Just guessing, but someone was in a hurry to get some carbs made so why not make a bunch of replacement carbs for the 84 H/O, pump out about 3500 or 4000 or so of them, and just restamp the ones designated for the 442s?

Here's the choke at full cold choke position, when you press the throttle before cranking to set the choke. Note the fast idle cam weight all the way up at the top because the choke spring is holding it up.

Here's the cold choke position which simulates startup and the primary vacuum break would draw down and pull the choke slightly open just overriding the choke spring for that little amount.

And for funsies, here's a factory-installed 85 442 carburetor built the previous day, Tuesday, June 5, 1984 and it got the overstamp. AFAIK, all 85 442 factory carburetors were technically replacement 84 H/O carburetors with an overstamp. Got a feeling that this may have been one of those times they actually used "leftover" serialized parts to make the 85 442. I haven't actually checked the manufacture date on my black 85 442. I'll have to get around to that and see. I do know it has an overstamp.

And strangely, they waited until January 6, 1992 in this case, to manufacture replacement 85 442 carburetors. Here's one of my new 85 442 replacement carbs. Notice it has no overstamps.