IDA3C Weber Troubleshooting Options

[Cfletch]

Hey there everyone, working on getting my 6 conversion going here and I was able to hook up a temp fuel system in place of my tank while I am waiting on a few parts. I wanted to get the car to idle with its new fuel pump (not yet regulated down to 3.5psi) rated at 5 PSI max. I wanted to get the carb bodies full of fuel and get some pressure into the system and as soon as the pump turned on with the ignition the carbs essentially started dumping fuel down my intakes. Almost as if there was an internal leak causing fuel to just enter their respective cylinders. I'm new to down draft webers so this confuses me. I popped the top off of one of the carbs and noticed the fuel level was extremely low in the bowls so it was not like the needle and seat were stuck or a float was stuck causing it to overfill. Kind of stumped here as these carbs are rebuilt. Really any suggestions are good here. the float level was set, the needle and seats are good and not sticking at all.

I read somewhere but not in much detail that the bowls are vented? I have these little plunger-esq things in each vent tube that I have not yet pulled out. Would that be the source of my problem? If the bowls couldn't vent its just pressurizing the changes and causing the fuel to just leak down into the engine?

[Graydingo]

My vote would be stuck or faulty float needle. I noticed that occasionaly, an air bubble can form when you swap out the carb - take it off for cleaning or whatever, and to alleviate this, run the pump for a second, turn off the system. Remove the hexagon cap over the needle valves, and reseal. If you still have trouble, take a look at your needle valves and make sure they can close and open without resistance. There are a lot of cheap less than versions on the market. I've purchased brand new ones only to have them stick.

If the needle /valve doesn't close, fuel will pour into the float bowls and spill over the tops directly into the cylinders.

While your PSI is not ideal, 5 psi should still function. You of course want around 3.5 psi.

Agree that you need the float bowl gauge and to set them, but this sounds like the needle is stuck open.

Here's another really odd thing, but I'll mention it just in case. I kept having one of the float bowls low and gas was draining into the cylinder after power was turned off.

It turned out to be two tiny holes behind the chokes that came from the back float bowl. Fuel was draining out of the float bowl area directly into #3 cylinder.

Also if fuel is filling up the cylinder, you need to be careful about hydrolocking as you can cause some serious engine damage if that happens.

Pull the plug and make sure there's no fuel in there.