Almost a year ago I bought an 87' Dodge B150. It's got the 225 /6 topped with a Holley 1945. I cleaned/rebuilt the carb a few months ago, then I drove it for over 1000 miles without issue.

One day it starts running rough. It won't idle, and I can see gas dripping onto the intake. I take it home and I took the top of the carb off. I checked that the floats were adjusted to the correct height (brand new metal floats), and I checked that the needle and seat were sealing properly. Everything else seemed fine too, so I put the carb back together and went to run it, but I have the same issue. I can get it to run with the throttle cracked, but it won't idle. While it's running it's leaking fuel from the accel pump linkage where it goes into the carb body (see picture).

Any ideas on what might be going on here? Carb had no other drivability issues before this started happening. Any advice greatly appreciated.

Check that the evaporative emisison control system (charcoal can and its lines, hoses, and valves) are all in good condition and hooked up correctly; info here. Be sure the hose routing to and from the charcoal can follows Chrysler's directions as described here and pictured here. For a quick Dx, remove the 5/16" hose connected to the nipple below the "el" in "fuel" in your pic. See if you're getting liquid fuel in either direction at that junction.

If no problems found in the evap system, then it sounds like the carburetor is overfilling/overflowing despite your inspection; quick first thing to try would be a new inlet needle and seat. Make sure it is the correct kind, with the captive needle.

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Too many people who were born on third base actually believe they've hit a triple.

I checked the needle and seat. I was using the correct style (captive needle), but I swapped it for a new one from a rebuild kit anyway. Both seemed to work fine on the bench (worked fine with the float as well when I filled the bowl with gas), but both produced the same running issues.

I haven't have time to check the entire charcoal can line routing yet, but I can say that there is no gas in either direction from the fuel vent nipple/hose (I pulled the hose off while it was running). I pulled the canister purge line off, and i can't get air through it either way.

I still have to keep the throttle cracked for it to run. Idles horrible, and will die after a while. Didn't want to idle no matter the fast idle cam/choke position either, at least when it was cool. It would idle on a fast idle setting when warm, but not at curb idle. I checked down the throat of the carb while it was running, and it didn't seem to be getting excessive fuel.

It wasn't leaking out of the accelerator pump linkage anymore, but after I ran it for a few minutes and shut it off a little fuel leaked from the area in the photo. Not sure exactly what part that is as I can't identify it in the Holley manual for the carb.

When I can I'll check the rest of the charcoal canister routing, and I'll check a few other things such as the ignition system.

Thanks for the help, keep it coming please!

The ignition system surely isn't causing carburetor overflow.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I agree, but it doesn't seem like it is overflowing anymore. It leaked a little from around that bottom area of the carb (after shutdown) even when it ran fine. It went from running fine one minute to having this issue the next, so I also want to rule out issues which may be causing poor ignition. Especially considering I can't see any excess fuel flowing into the carb when the engine is running, and the exhaust isn't smoking like it would usually do if it were running rich.