Won't start after Weber install and initial tune.

I completed my Weber conversion, set a base line tune as per Pierce Manifolds instructions (settings for idle speed and idle mixture screws) and it started right up.

After my first test drive I raised the idle speed a tad via the idle speed screw because it was idling a little rough once it had warmed up. Then I called it a night.

The next day, I start it up, no trouble, and take it out for a quick spin. When I pull into my driveway and shut it off, it runs on pretty badly. After it totally dies I start it again and kill it once more; it runs on even longer.

Now, after all this, it will not start without me on the gas, I've re set up the idle screws multiple times. If I let off the gas, it stalls , but no running on. It seems to getting 3psi of fuel consistently so that doesn't seem to be the issue.

Take the carb apart, blast all the ports out with carb clean. Also make sure your fuel line is clean (disconnect it just after the pump/filter/things you don't want to damage) and shoot it compressed air through it if possible). Just had mine clog up on me after rebuilding my engine, really ruined the successful feeling of all the work I did.

I'm doubtful that's the issue. The carb is brand new, as are all my fuel lines, filters and fuel pump.

OOC, who supplied the new Weber? There are bad licensed knock-offs everywhere and plenty of people have been burnt by them...

I got mine from Pierce Manifolds. It has Weber casted into the body and a white choke unit, so it's real as far as I can tell.

Try this site http://www.carburetion.com/troubleshoot.htm

Lean Best Idle http://www.carburetion.com/Weber/adjust.htm

The issue ended being very simple but deceiving. A vacuum port cap had been shot off the intake manifold when the motor dieseled. The first one was lost, and the second is now being held on with a hose clamp. My initial tune was refined and the truck now runs well (albeit aside from the intermittent dieseling). I plan to take it to a shoo to have it properly tuned with a vacuum gauge and such.