New World Datsuns...

So coming back from Canby I ran into traffic in Tacoma and my car just died when I put the clutch in. It started right back up and I could keep it running by giving it gas, but once I let off the gas it would just die. I made it home with a combination of revving it when slowing down or stopping and pulling the choke out a bit.

Until this happened the engine had been running great - smooth power from idle on up though I've never gotten it to idle below about 1000 rpm. I've had no hesitation when starting from a stop. I did notice what was likely the sound of a vacuum leak a few weeks ago but naturally I ignored it since it has been running so well. I'd only hear it sometimes while idling and it would go away once I hit the pedal.

Engine/carb: L20B with a 32/36 manual choke Weber. The carb is a Redline Weber and was purchased new in November 2012 and can't have more than a few thousand miles on it.

Symptoms: The engine won't idle - it simply dies when I let off the gas.

Here is what I've done/found:

- Vacuum advance hose had broken resulting in a huge vacuum leak. Fixed but issue still exists.
- Adapter plate was loose likely another vacuum leak. Fixed but still didn't take care of the problem.
- Fuel filter replaced.
- Float level checked and looks fine, plenty of fuel in the float bowl but not too much.
- Primary and secondary idle jets removed and blasted with carb cleaner. Neither seemed to be blocked in any way.
- Idle mixture screw removed, carb cleaner sprayed inside, replaced and set back to where it was.
- I've checked everywhere for any cracks or vacuum ports that are unplugged and can't find anything.

Since the engine won't idle, I can't really use the typical methods for tracking down a vacuum leak but I'm thinking it might be fuel related anyway. Whether carb or vacuum related, what is my next step? I'm not really a carb person though not that long ago I didn't know half of what I do now.

Thanks in advance.

Tim

Tim, you mentioned that you cleaned the idle mixture screw and hole, but did you clean the idle jet on the side of the carb? Clean that...

Once you get it to idle, generally the main reason that a weber will not idle below 1000 is due to a vacuum leak, but not always. Sometimes it is just adjusted wrong and hanging up on the lowest choke cam setting.

I removed and cleaned both the primary and secondary idle jets, though it's possible I was looking at the wrong things. I had found some images and it looked like there are brass screws on either side of the carb that hold the idle jets in place - those are the ones I removed and hit with carb cleaner.

I have a lot of vacuum tubes that are just crimped off from someone partially removing the emissions crap and it's very possible I have a leak from one of those tubes. I *should* properly remove everything or at the very least cut the tubes and cap everything off, but it's never been too big of a deal with my idle around 1000 or so. This new issue though is getting irritating.

To bad you weren't closer man I'd swing by! Usually super simple fixes.

izzo wrote:To bad you weren't closer man I'd swing by! Usually super simple fixes.

Initially I figured it would be something really obvious that I just overlooked but more and more I'm thinking I have some blockage in my carb. I'm trying to find another Weber locally that I can just slap on and test but no luck yet.