Engine won't idle - L20B w/Weber 32/36

[67_1600]

On my way home from Canby, I hit some traffic and my car just died when I put the clutch in. It started back up just fine but as soon as I let off the gas it just dies. It runs smooth other than that - it just won't idle. I figured either major vacuum leak or maybe fuel related. Here is what I've done/found:

 

- Vacuum advance hose had broken and was fixed (didn't help)

- Adapter plate was loose and was fixed along with gaskets replaced (didn't help)

- Float level was checked and is fine

- Fuel filter was replaced

- Carb was pulled off, all passages sprayed with carb cleaner, nothing found to be blocked

- Inspected for other possible vacuum leaks (cracks, anything unplugged or broken), nothing found

 

The week or so before Canby, I did notice a whistling sound that was likely a vacuum leak when the engine was at idle. As soon as I gave it any throttle it would go away and it didn't seem to be affecting how the car ran so naturally I ignored it.

 

Yesterday I hooked up my vacuum gauge to the manifold while cranking and it seemed to register plenty of vacuum - it would max out just under the green on my gauge which is at 17". I also placed my hand over the carb while cranking and could feel vacuum as I would expect.

 

When I sprayed out the passages in the carb, I removed the different jets to inspect/clean them as well. I also put the tip of the carb cleaner tube in the idle fuel passage under the throttle plate and sprayed and had the cleaner shoot out of the air passage above the primary idle jet and also some went into the float bowl through the primary main jet. It didn't shoot out of the jet but I'm not sure whether I should expect it to or not. I went in reverse order and did get fuel out of the idle outlet hole but, again, it didn't shoot out, more of a restricted flow - does that indicate a blockage or should it be restricted to a point so it doesn't shoot out? 

 

So what should be next on my list of things to check?

 

Thanks in advance.

[metalmonkey47]

Did you check to make sure you had 12V at the idle cut solenoid? It's facing the passenger side of the car, where the primary idle jet goes. Without that, there's no fuel delivery at idle.

[67_1600]

Mine is a manual choke and there is no idle cut solenoid. This is how mine looks on the passenger side:

 

[dr.feltersnatch]

dumb question but did the idle screw vibrate loose?

[q-tip]

^^^^that was going to be my suggestion

[67_1600]

I have a feeling it's going to end up being something simple like that but the idle screw is there and I've played with it a bit to see if it might be the cause. From what I can tell, the carb isn't missing anything and all potential sources of vacuum leaks are sealed. I'm going to take the carb apart again tomorrow to see if maybe there was a passage that I overlooked that might be blocked.

 

Is there anything electrical I should be looking at? A friend sent me something showing that it could be an electrical issue, but it didn't include any specifics as to what to look for.

[datzenmike]

Vacuum advance hose ok? hooked up and no cracks or leaks?

[67_1600]

It appears to be fine though it's not in the best shape - probably not a bad idea to change it either way. 

 

One note about that though - I hooked up my vacuum gauge to the port on the carb and cranked it and it read zero. I was curious, so I looked at the carb and the hole for vacuum is above the throttle plate, which means it shouldn't register anything unless the throttle was open at least slightly. So even with the fact that my vacuum advance hose had broken off, it shouldn't have made any difference at idle since my plate is completely closed. I know I can 'cheat' by adjusting the idle speed set screw (not the mixture screw) but that's not how the system is designed to work and I've never had to run it that way in the past.

[datzenmike]

Correct. There should be zero vacuum advance at idle.

 

 

Well check the EGR valve. If dirty it may not close. If it's slightly open inert exhaust will leak in and there and dilute the fuel/air and it won't idle.

[67_1600]

Some PO of my car did a half-assed job of removing much of the emissions crap including the EGR valve. Much of the tubing was just cut and then crimped and it looks like some larger gaping holes were filled with JB Weld or something. I don't see anything that is different than it was before and also can't locate any noticeable holes. The fact that I'm building pretty decent vacuum when cranking it makes me think that maybe it's just an issue with my carb - maybe I sucked some debris into it and it's limiting the flow of fuel through the idle hole/port or whatever.

 

Here are some pics of my mess:

 

 

 

[67_1600]

More and more I'm thinking the issue is with my carb as I get good vacuum readings when cranking it and also once it's started. So I'm wondering if anyone in the greater Seattle area might have a known working Weber I could throw on it just to see if it truly is or isn't the carb. I've tried carb cleaner and compressed air on it, so if there is some debris in there it's not going to come out easily.

 

Thanks!