It Was Running Fine a Week Ago...

[HeavyFuel]

...but now it just chug...chug...chugs up the street.    

Seems like a fuel delivery problem.  The engine idles 'fairly' decent, but not as good as it did.

Checked timing...same....10* at 750 rpm. 

RPM/idle is somewhat irradic, although that is nothing new.  The rpm varies in a range of about 30-40 rpm (720-760 rpm)....don't know if this is normal.  Should the idle be rock steady?

Vacuum reads pretty decent....16 inches with the idle adjust screws (original Carter 4429s AVS) set at about 2.5 turns CCW out.

Stumble becomes more pronounced when driving....severe off idle...and remains rough until engine gets to about 3K rpm.  Then it smooth's out for the most part.

When tooling along at about 25 mph, steady throttle foot, the engine surges up and down.....like it gets fuel, then not, etc.   It cycles like that a couple seconds per cycle.

The bowls are full.  ( I checked by spraying carb cleaner into the vent hole....if it's full, the fuel splashes up a little)  

I use 91 Shell V-power, and add a bottle of Amsoil octane boost.


What the heck could make it go from great to crap....over the course of about two days?       Don't really want to sit like this all weekend.  

[HeavyFuel]

Could an inoperable distributor vacuum pot cause this?        

The distro is a couple year old Firecore unit...I don't think that it's pot could go bad already.....I'm just spit-balling'...

[BLK 68 R/T]

Coil maybe?

[HeavyFuel]

I'll give that a try ...

[LaOtto70Charger]

I have been having all kinds of issues getting my 318 running with its points latelty. Mine started coughing and almost dieing while going down the road last year at 70 mph.   Right now it idles fine. Give it fuel and it coughs and almost dies. Sometimes it acts up even at idle once warmed up.  This in the gage in park, and on the road. If this sound similar good luck.  I cant eleminate fuel or electric issues.
I put my old distrustor (put a rebuilt one in last year a month before the issues) and it ran fine.  I put the new one back in and runs like crap. Tore them down and both seem fine.  So if you have the old distributor you may try that. 

Also I was noticing my fuel boiling in the carb after shutdown. I could hear it percolating away when the engine shutdown. Next up is spacer and fuel line wrap for me. Lines felt pretty warm so not sure how much that has to do with it either.

[RECHRGD]

Are you using the round Firecore coil?  Ron had mentioned that there was some issues with those on the RTR distributors.......

[hawkeye]

Did you just fill it?  Water?

[HeavyFuel]

Not using the Firecore coil.   No recent fuel fill.

Swapped the coil....no effect.

Swapped the ECU....no effect.

Used deoxit on the bulkhead connections...no effect.  Well....I can't say no effect, the connections  are no doubt better.  It just didn't fix my problem.

[HeavyFuel]

Progress.

I didn't mention that the fuel tank was almost empty the last couple days.

And for the last week or so it's been hot and humid.   Maybe a connection.

So I filled again this morning.   While I was doing all the wholesale changes mentioned above.....could it have been bad fuel....water in tank... something similar I wondered.  

Just now went out and got on 'er pretty good for about 10 minutes.  40-50 mph out.  Hit about 70ish on the home stretch....didn't want to push it too hard.

By golly, it actually seems to running pretty close to it's old self.

[69wannabe]

Could very well have been water in the bottom of the tank, check your fuel filter too just to be sure it isn't stopped up with trash. May check your spark plugs just to be sure they are not fouled or close to being fouled and then you will know if it is running richer than normal. Is it a completely stock engine? That timing seems a bit low to me but if it is all original then that may be plenty of timing with a stock cam and heads......

[HeavyFuel]

Stock rebuild.    If I go with much more timing, she starts to ping when under hard throttle at low rpms.

Went on a short drive tonite, and it's purring like a kitten.  Feels better than before it was acting up.   

Man these things are touchy....at least  mine is.   

[LaOtto70Charger]

Mine has become extremely touchy lately too. I am back to a 14 year old points and Condensor with the original distributor because it reacts up if I change the whole thing or bits. Used to be she just wanted autolite spark plugs.

[HeavyFuel]

My original Carter 4429s has got a manual choke hooked up because of the CH4B that's underneath....no divorced choke well to utilize in that aftermarket manifold.

I wonder if maybe the choke was not coming all the way off for some reason, and now is.   I suppose a stuck choke would cause crappy symptoms like mine had.    

The in and outside of the carb did get sprayed with carb cleaner in between everything else I was throwing at it.   Maybe it unstuck something.

(trying to record the events so that maybe one day this thread may help others)

[68CoronetRT]

After dealing with fuel issues for a while, I'd check plugs first, then fuel pump pushrod for length and then a cheapo fuel pump just to make sure its not fuel delivery related.

My car was running like crap, threw in a new fuel pump and the problem went away, then I installed EFI with an intank pump and have been problem free every since...