engine and drivetrain Weber 32/36 Was Running Fine Until This Morning - Won't Idle

[enoklite]

So my 02 has been running the 32/36 (electric choke) with no troubles at all since I bought the car--cold starts start right up and idle well at both fast idle and then runs smoothly at normal idle.

Then this morning I engage the electric choke as usual, and it idles fine on the fast idle cam at ~3000rpms, but as soon as I hit the pedal again it instantly dies.

 

I was able to hold the gas at stops so that I could get the engine warm, and the problem still prevails. It simply goes straight to 0 rpms as soon as I take my foot off the gas.

 

I have checked both the primary and secondary idle jets and they were both completely fine. I do not suspect vacuum leaks as I sprayed gumout around the carb and no changes (higher rpms or hesitation) occurred, though I was only able to do this on the fast idle and the problem is at regular idle. 

 

Pretty stumped as I have not had any such trouble in the past, and it seems that in the 12 hours or so that it has been parked overnight it has developed this problem.

 

Any ideas would be appreciated but I will be troubleshooting until I get to the bottom of this...

[73touring]

Try pushing compresses air through the idle jet drillings. My air correctors get blocked up from time to time and when I do this it clears them out.

['76mintgrün'02]

On some Webers there is an electric idle shut off valve which will not allow the car to idle, unless it is getting 12V.  You might check to see if yours has this feature (passenger side of carb) and whether the wire is hooked up and getting power with the key in the on position.  If it is getting power, you can check to see if the valve is working by taking the wire on and off and listening for a small clicking sound (with the key on).  That is where I would start.

[Mike87]

^^^+1

 

Electric idle solenoid.

[enoklite]

Thanks for the advice! I do not however have an electric idle solenoid equipped on my carb.

I will also try blowing compressed air through the idle jet drillings--hadn't thought of that!

Edited October 27, 2014 by enoklite

[Roland]

I have checked both the primary and secondary idle jets and they were both completely fine.

 

Any ideas would be appreciated but I will be troubleshooting until I get to the bottom of this...

 

 

 

Like the others, the primary idle jet is where I would start.  Parenthetically, I think we are all assuming you have a spark and your distributor has not been inadvertently moved, as can occur if the 10mm hold down is loose.

 

Edit:  I see where you do not have an electric idle solenoid, so I am revising my comments regarding the same.  Carb cleaner under pressure in both the carb orifice and the jet is the next order of business.  Even the mixture screw can be affected by dirt and/or gum, so remembering your starting point (X turns in to lightly seat), it may be worth cleaning.

 

The.idle jet typically fitted with a rubber o ring.  If the ring is compromised or missing it may prevent the jet from properly seating in the carb body.  Likewise, a loose jet can function as nonexistent jet.

.

Another thing that might cause or contribute to your hard start-no idle problem is your choke.  Yes, I am aware that you did not mention a flooding or rich condition.  Closing when cold is good but if the choke hangs or fails to open you may experience a very poor or nonexistent idle.

 

hth

Edited October 27, 2014 by Roland

[enoklite]

So I have continued to spray carb cleaner around the carb/intake manifold while on the fast idle and I've found that spraying around an un-capped-off metal "hose" on the driver side of the intake manifold just at the base of the carb raises the idle speed substantially. I'm currently waiting for the choke coil to cool off so I can start it again and have it idle. I will then plug said metal hose and see if that changes anything. 

Does anyone know what this metal hose is? I will take pics of what I'm talking about when I go back out there.

[kinarcy]

What is the lowest idle you can maintain with your foot on the gas?  

 

this isn't directly related to your issue, but did you say the fast idle is at 3000 rpm?  That is a bit on the high side -- I would shoot for 1000-1500 if that is enough to keep the motor idling nicely when cold.

Edited October 27, 2014 by Dave D

[73touring]

I think thats for the distributor vac. I dont have that on mine. I have one in the carb that meters advance post idle but at that point on the manifold it is always active, if you have a purely mechanical dissy. Just block it off with a bit of hose with a screw in it or someting else to cap it.

[enoklite]

Alright guys--I plugged this mysterious "nipple" thingy with a rag and then it idled just fine. So...problem solved for now. I don't see any loose hoses that would have attached to this. I assume this tube was capped off with something that fell off.

[kinarcy]

sometimes the rubber vacuum caps on nipples like that get hard and "give up" or a backfire could have popped it off.

[enoklite]

Here is a pic of the nipple in question:

 

Edited October 27, 2014 by enoklite

[73touring]

Thats for the horrible emissions gizmos. Block it off. Nice to find easy fixes[emoji1]

[enoklite]

Alright, have it blocked off now and its running like before. However, I'm going to have to slowly retune some things I messed around with before I actually fixed it. ARGH!

[Roland]

Here is a pic of the nipple in question:

 

 

 

 

EGR fitting (exhaust gas recirculation).  Search EGR and it should provide plenty of insight.  Surprised you did not mention the tremendous sucking noise it produced when unplugged. Some of us simply cap it off with a plate

 

 

 

 And the existence of  this fittings strongly suggests you have a similar plug at or near your exhaust manifold.  http://www.bmw2002faq.com/topic/131608-how-does-this-smog-pipe-come-off/