View Full Version : Carb 2.8 No fast idle kickdown
So the weather is cooling down a little and I discover hitting the gas after starting my motor does not result in kick-down. I figured I have an issue with the electric choke heater BUT:
1. Off idle performance is fine.
2. Today I was sitting at a light foot on the brake, motor on fast idle, then suddenly it "kicked itself down".
Anyone have any other ideas other than choke heater? Maybe a misrouted vacuum line? I've been out of town for a few weeks and I haven't opened my hood in over a month, and probably haven't had my air cleaner removed from the carb in almost 2 months.
Century7667
11-13-2009, 11:04 PM
Back in the old days we had something called a 'choke pull off' diaphram. They ran vaccum, and when they got old, they quit working. They work to pull the choke open once the engine starts running and pull against the choke coil. I've seen setups with one and two of them, at the top of the carb near the choke butterfly.
If you have them, start the care with the air cleaner off, look to see if they 'suck in' once the engine starts. Back in the '80's when I was working on my '70's stuff I purchased one once. It was about $10-15. Not part of the standard carb kit.
Ken T.
Back in the old days we had something called a 'choke pull off' diaphram. They ran vaccum, and when they got old, they quit working. They work to pull the choke open once the engine starts running and pull against the choke coil. I've seen setups with one and two of them, at the top of the carb near the choke butterfly.
If you have them, start the care with the air cleaner off, look to see if they 'suck in' once the engine starts. Back in the '80's when I was working on my '70's stuff I purchased one once. It was about $10-15. Not part of the standard carb kit.
Ken T.
Yeah I finally got around to looking at it today, and the choke and both vacuum breaks (choke pulloffs) appear to be working properly. On the air cleaner theres a sensor that decides whether or not the the rear (as if the engine was in a RWD car) vacuum break gets vacuum..... now that I'm thinking about it, it could be the problem....
Early this decade I had an 88 Cutlass Classic 307 Q-jet, that would idle lousy until it warmed up a little and the problem was the vacuum break.
turbokinetic
11-14-2009, 01:14 PM
I had a VarajetII on my 2.8 several years back.
The choke-heater adjustment was critical in cool wether because it does respond to ambient temperature as well as the electric heating element.
When it is stuck on fast-idle, and the engine running; pull the air filter off (as far as you can without unhooking any hoses) and look at the stepped fast-idle cam. See if the screw is really riding on the fast-idle portion of the cam. If the screw is NOT actually riding on the cam it could be a binding throttle cable or linkage. If it IS riding on the cam, the choke heater may need a slight adjustment.
Hope this helps!
David
I had a VarajetII on my 2.8 several years back.
The choke-heater adjustment was critical in cool wether because it does respond to ambient temperature as well as the electric heating element.
When it is stuck on fast-idle, and the engine running; pull the air filter off (as far as you can without unhooking any hoses) and look at the stepped fast-idle cam. See if the screw is really riding on the fast-idle portion of the cam. If the screw is NOT actually riding on the cam it could be a binding throttle cable or linkage. If it IS riding on the cam, the choke heater may need a slight adjustment.
Hope this helps!
David
The screw is on the fast idle cam. It's probably the choke. I rebuilt the carb when I bought the car so the choke spring housing is already screwed together rather than riveted..... I assume the adjusting it requires going in there....?
turbokinetic
11-14-2009, 07:39 PM
If the screw is just _barely_ on the edge of the cam when it is stuck; just loosen the screws and rotate the choke cover towards "lean" until the screw just drops off the cam. Should fix 'er right up!
If the screw is just _barely_ on the edge of the cam when it is stuck; just loosen the screws and rotate the choke cover towards "lean" until the screw just drops off the cam. Should fix 'er right up!
If I remember correctly the choke cover is "keyed".
turbokinetic
11-14-2009, 08:33 PM
Yes some of them are and you have to file away the notch on the plastic part. Been along time since I've fooled with a carby!
turbokinetic
11-14-2009, 08:45 PM
Should fix it right up! Let us know.
Thanks,
David
Should fix it right up! Let us know.
Thanks,
David
Still haven't looked at it further. Still runs on fast idle for about 2 miles in the morning. Still desperately need to replace my water pump. I work on taxis and limos 6 days a week (sometimes 7), and get lazy with my own car. What was that they say about shoemakers? :lol:
Hopefully tomorrow I'll have time to replace my water pump (and all my belts, and reseal my AC compressor, and replace my front crank seal). As far as I know all I got going on tommorrow is some maintanence work on an Excursion taxi and a fuel filter (that I couldn't get the correct one today) for some obscure Suzuki, and a coolant temp sensor, and alternator belt replacement (no ac or power steering on this luxury car) and general lookover on an 87 Hyundai Excel (lol).........
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