hotter weather and now surges/bucks/chugs on acceleration

[JayRamb]

My 85 Eagle BBD started to really surge and chug when accelerating. Sometimes it will do it and sometimes it's really bad. Seems to have happended with the warmer hotter weather. All vacuum lines have NO leaks and are all new. Carb overhaul back in February. Operated great until now. New fuel pump and filters. My guess is that the choke is too lean? I have it set at 2 notches lean and the idle screws leaned as well. Timing is on, doesn't miss at idle. The stepper motor does what it should. All linkage is working as well Could it be the acceleration pump adjustment needed? It doesn't surge at steady speeds, but on highway, when stepping on it, it will chug./surge. Stumped.

[IRON HORSE]

Hello,
     You mentioned new fuel pump and filter, my first choice too. I have found the carb settings pretty forgiving .. have you checked timing / ignition system, like coil breaking down under load..??  I made a coil to cap wire that I wrapped with about 100 turns of enamaled wire to make a transformer. Then wrapped that ball of wire with tape to protect it, but left  leads ( two wires ) from the wrapped ball of wire so I could connect small gage speaker wire to them. I ran the speaker wire into the car thru the fire wall ( found a hole ). I then connected the speaker wire to a small neon bulb being careful not to short the leads. When the car was running the coil firing induced a voltage in the wire wrapped around the main ignition wire which lit the neon bulb. As I ran the car down the road the  neon light stayed lit .. but when the ignition system failed the neon bulb went out for a second... problem ended up being the pickup in the distributor ..  anyway I'm "rambling" on .. to get to my point ..this little ckt helped me confirm the ignition as the problem.  Keep us posted .. would like to hear what you find as the cause.
                                                               Good Luck, Iron Horse

[carnuck]

Do you have the horseshoe connector? Temp messes with them over the years plus corrosion. I cut mine off first thing and replaced the coil with a Napa IC12SB (or IC12 which is just more expensive). Started faster and revved better.

[JayRamb]

Do you have the horseshoe connector? Temp messes with them over the years plus corrosion. I cut mine off first thing and replaced the coil with a Napa IC12SB (or IC12 which is just more expensive). Started faster and revved better.

I have the upgraded ignitions on both my Eagle.

[macdude443]

Upgraded how?  If the stock style coil connector is still present (looks like a horse-shoe) they are known to get gross and become intermittent.  I bought a new coil connector from somewhere to splice in.  Costs maybe $6.  You don't have a fuel line up against a manifold or anything creating vapor?  Is your filter return port in the 12 o'clock position?  I had issues with my ignition module that caused a very bad miss/surge.  It was a brand new module from Standard Motor Products.  It would run great for a little bit and then it'd act up, badly.  They don't all just completely die when they fail.

[carnuck]

If you pull the gas cap, do you get a whooshing sound?