85 305 in a k1500 - wont idle after smog removal

[scrap--metal]

not idling unless I baby it a bit.

If you baby it for a few minutes, until it's warm, will it stay idling/running now? If so, the choke likely needs attention. The vacuum leak at the evaporation canister was probably (hopefully) your biggest hurdle to overcome.

I also have messed with the choke screw. what is the best way to set that?

Your quadrajet should have an electric choke on the passenger side. Assuming the choke spring is good and everything works properly, you should be able to floor the accelerator pedal on a cold engine and the choke plate at the top front of the carb should close. Verify this with the air cleaner off.

Based on your video posted yesterday, it sounds like the choke is working. It has a high idle when cold, which is good, and then it dies when it seemed like the choke was coming off, which is bad.

When the engine starts, the choke gets power and begins to heat up the coiled spring in the choke assembly. This heating of the spring is what opens the choke plate on the carb. With the engine warm, or cold a cold engine before the accelerator's been touched, the choke plates should be wide open. This can be confirmed with the air cleaner off as well.

If the choke plate is not opening or closing entirely, sometimes it can be cheated as a temporary fix. There should be three screws around the perimeter of the electric choke. Loosen them and the assembly can be rotated to close or open the choke. This will not give you the functionality that you want, but it may help get your truck running if the choke is not opening on a warm engine or if it's not closing on a cold start. It sounds like your choke is working to some extent though.

There is a screw that adjusts he high idle speed though. It sounds like your high idle speed is faster than necessary.

 

[Bextreme04]

One addition to this. The choke will not open as it warms up. As the coil inside the choke housing warms up it expands and stops putting tension on the plate. It will still be held closed and on the high idle cam by the tension in the linkage until you tap the gas pedal. Once you tap the pedal it will snap open and come off the high idle cam.

The appropriate order of adjustments is:
1. Make sure initial timing is correct on a warm engine at idle rpm(650-750rpm) with the vacuum advance disconnected and plugged at the carb.

2.Adjust the mixture screws for highest rpm and then lean by 50rpm.

3. Reconnect the vacuum advance

4. Reset idle RPM to desired

5. Let engine cool fully

6. Set choke by pressing gas pedal all the way to floor once and then slowly release it.

7. Start engine and immediately adjust high idle set screw so engine is at ~900RPM

8. Over the course of 1-2 minutes the engine RPM should climb up to ~1200RPM

9. Once engine RPM has stopped climbing the intake manifold is fully warmed and the choke spring should be released. Tap the throttle and idle should drop back down to the previously set idle RPM.

 

[scrap--metal]

One addition to this. The choke will not open as it warms up. As the coil inside the choke housing warms up it expands and stops putting tension on the plate. It will still be held closed and on the high idle cam by the tension in the linkage until you tap the gas pedal. Once you tap the pedal it will snap open and come off the high idle cam.

Good catch! This is confusing to someone unfamiliar with these carbs. I know I didn't understand it at first.

 

[Bextreme04]

Another thing to watch out for is the choke pull-off. If you have the air cleaner lid off you should see the plate FULLY closed. When the engine catches on startup, you should see it open a little bit. If it doesn't open a bit when the engine catches, you likely have a bad choke pull-off(it will be the small vacuum can on the choke side of the carb). My truck has two and the secondary one likes to go bad for some reason. If it goes bad, you will have it dying like you described AND it will be a large vacuum leak.

 

[bbgbouncer]

thanks @scrap--metal and @Bextreme04 i will investigate and take pics.

 

[bbgbouncer]

I have tried to adjust the screws as was instructed. the problem is that it still wont stay idling enough for me to do anything.

I replace the cap and rotor. that needed to be done. so that is new cap/rotor, plugs, and wires.
I ran a compression check . 175psi on all 8 cylinders. (fuel/spark disconnected, all plugs removed)
I borrowed a small vacuum gage and check all the small vacuum ports/lines. consistent number no bouncing on the gauge.

just still cannot get the truck to idle. I put a tach on to get a sense of where it runs. I can get it to run steady at 1400 but if I let it drop to ~900 it dies.
Im not sure how to check the timing if I cant get a consistent rpm.

honestly Ive called around to shops to see if they might be of help. Im finding that it is old enough (non-computer) that no one knows how to diagnose and fix these. frustrating. Not sure what the next steps should be. Is it time to remove the carb soak it?

 

[scrap--metal]

I can get it to run steady at 1400 but if I let it drop to ~900 it dies.

Can you run it at 1400 rpm until it's fully up to temperature?

What is the choke doing? Have you been able to confirm that it's functioning, or at least not causing the truck to die on you?

 

[SirRobyn0]

So many pages have gone by I'm not sure if this has been said before, but I just rewatched your videos.

#1. EGR valve in when you unhooked everything and reconnected it, is there any chance it is hookup wrong and staying open.
#2. Is the a decel / idle kicker on the carb, is it hooked up and functioning.

I will think and post more later but you have checked so much I feel like something must be getting over looked.

As far as finding a shop is concerned you need to find a place with an old man working at it. That old man will be fed up with working on modern vehicles and quite happy to see your truck (ask me how I know). If you want to find a shop and you tell me where in Utah you are located I might be able to help find one, as (it is one of the services provided with my paying advice job).

 

[bbgbouncer]

@SirRobyn0 I think that you said that the decel valve should be on the front of the carb. I dont see one. you commented on a pic already that neither did you.
I believe the EGR valve is the one on intake manifold passenger side. I did remove it to get the valve cover off. it was put back on. however I have not tried capping its vacuum to see if that makes a difference. I will try that today.

As for running it hot. the other day I ran it for 20 mins. My though was the same to get it past the choke function. Even then it would not idle. I turned the curb idle screw in one turn at a time but this bottomed out before it would maintain an idle.

As for the choke. not sure that it is working. All I can say is before we changed the valve cover gaskets and "fixed" everything the electric choke worked great. I have attempted to adjust the choke idle screw, again to no avail.

@SirRobyn0 i would be interested in a shop around Lehi, UT. im out by Saratoga Springs.

I feel bad for my daughter. She paid half for the truck and it is not drivable because of my actions. It is a good truck and she loves it. Just need to sort out what this issue is.

 

[SirRobyn0]

@SirRobyn0 I think that you said that the decel valve should be on the front of the carb. I dont see one. you commented on a pic already that neither did you.
I believe the EGR valve is the one on intake manifold passenger side. I did remove it to get the valve cover off. it was put back on. however I have not tried capping its vacuum to see if that makes a difference. I will try that today.

As for running it hot. the other day I ran it for 20 mins. My though was the same to get it past the choke function. Even then it would not idle. I turned the curb idle screw in one turn at a time but this bottomed out before it would maintain an idle.

As for the choke. not sure that it is working. All I can say is before we changed the valve cover gaskets and "fixed" everything the electric choke worked great. I have attempted to adjust the choke idle screw, again to no avail.

@SirRobyn0 i would be interested in a shop around Lehi, UT. im out by Saratoga Springs.

I feel bad for my daughter. She paid half for the truck and it is not drivable because of my actions. It is a good truck and she loves it. Just need to sort out what this issue is.

You are right about the decel valve I remember that picture now sorry about that.

Try capping the EGR and see what happens. That would be a good test. As mentioned previously the 305 really can't be without it's EGR valve, it's fine for testing purposes but if that solves the idle issue we'll need to sort out why it is doing that.

Ok, I will get back to you latter today with possible shop leads.

 

[SirRobyn0]

@SirRobyn0 i would be interested in a shop around Lehi, UT. im out by Saratoga Springs.

I feel bad for my daughter. She paid half for the truck and it is not drivable because of my actions. It is a good truck and she loves it. Just need to sort out what this issue is.
[/QUOTE]
Ok, this is what I have. Keep in mind I have no personal experience with these shops so it would be best for you to check reviews and proceed as you would with any unknown shop. The only thing I do know for sure about these shops is that they work on classic / older rigs.

Sam's Automotive Repair 681 East State St. Lehi, UT 84043 (801) 499-6782
Roger's Automotive 198 West State Street Lehi, UT 84043 (801) 768-2590

That's all I've got. Let us know if you do take it some where please.

 

[bbgbouncer]

I called Sam's they seemed to understand the issue and age of the technology. Once I dropped it off I was encouraged by them having an old 70s GTO on the rack.

 

[SirRobyn0]

I called Sam's they seemed to understand the issue and age of the technology. Once I dropped it off I was encouraged by them having an old 70s GTO on the rack.

Good deal. I will add this to the conversation as well. Some of us, myself included are current or former mechanics, and if the shop says something that raises concern with you feel free to post it here and we'll let you know what we think.

 

[shiftpro]

I would buy a new carb. Like an 1150 Dominator... I like the model that comes with a 496 stuck on the bottom.

 

[bbgbouncer]

I did get a new carb as a precaution. an eldelbrock 1406. I got one from amazon incase wanted to return it. Ill see what the guys at the shop have to say once they take a look at the truck.