weird stumbling at iddle please help hurry, Charger is my daily driver. FIXED!!

[Nacho-RT74]

Ok... my car suddenly starting to fail at iddle last night. I press gas pedal on a corner and when I stopped on a traffic light the car started to make just like a "machine gun"... engine never died, not even with A/C ( almost but didn't ), but iddle was extremelly low and sounds and stumbling like a machine gun.

when I pressed the gas pedal again to keep riding everything was all right during acceleration and medium and high rpms... fail is just at iddle.

I stopped to check what could it be but didn't found nothing. I smelled the exhaust to check for gas leak and mixture on carb and exhaust make me cry my eyes like, however didn't get black smoke.

Arrived at home and change the car for my parents one. On the way everytime I was stopped, iddle was the same... This morning I was to check the carb, but really I'm lost on this. Don't really know if is Carb or electrical fail... rotor, dist, ballast, ign module...

Really lost.

Note appart. I had oftenly a backfire... not common as some time ago, but lats night I got three backfires  in just 5 blocks ride when I press gas pedal once I had stopped on a corner.

damn, I'm really lost on this... The machine gun stuff never did happen me before

PLEASE HELP HURRY

[69chargeryeehaa]

your setup would be helpful, engine, carb, dist??

[Nacho-RT74]

400 stock
carter Thermoquad
electronic ignition 4 pins...

is Pure stock engine.

[69chargeryeehaa]

well my order of trouble shooting would be to check the timing, check spark see if it's good, i've seen a worn wire arcing to ground cause those idle issues, obviously check cap for cracks and the rotor.  also look under the hood at night to see if you see and arcing from the wires, if that checked out ok i'd then to a compression test, check/clean/replace plugs while i'm at it, elliminate a internal problem, if that checks out ok, i'd check for manifold leaks using propane torch not lit and go around the base of the carb and around the intake manifold and watch for a increase in RPM's.  if that checks out all ok, then i'd take apart and clean/inspect/rebuild the carb.  that would be the order i'd attack the troubleshooting, from eaisest to hardest.  good luck, report your findings. 

[Nacho-RT74]

ok, on another note:

I'm removing every night since two weeks ago, the rotor from dist to save my car of stole intentions. That's the solution I have found right now since I lost the parking place at my buliding ( the neigbourgh who had rented the place to me got his son with car get back ) and my car is being parked outside. No one thief will have a Rotor on his pocket to stole my car specially if they don't know.

That could be a reason to get some damage ? I can't find any visible damage on cap or rotor, just some burned spots on top of rotor around the central point, where the spring that match with incoming spark point on cap is.

I was starting on think is an electrical issue, since in my experience, carb problems are not THAT regular with THAT perfect timming/beat... exactly like a machine gun. My carb issues with iddle have been irregular, and specially keep during acceleration.

The carb is recently rebuilt, but with a TQ never knows LOL.

[69chargeryeehaa]

also a few other things came to mind, check you fuel filter and fuel pressure, fireing order, and make sure your plug wires are seperated and not cross fireing.  it could be a million things, but check out the basics first, then get into the hardcore stuff.  the noise concerns me, "machine gun" sounds are never good.  you could have a leaking float in the carb, running rich, or a bad float valve seat.

[69chargeryeehaa]

ok, on another note:

I'm removing every night since two weeks ago, the rotor from dist to save my car of stole intentions. That's the solution I have found right now since I lost the parking place at my buliding ( the neigbourgh who had rented the place to me got his son with car get back ) and my car is being parked outside. No one thief will have a Rotor on his pocket to stole my car specially if they don't know.

That could be a reason to get some damage ? I can't find any visible damage on cap or rotor, just some burned spots on top of rotor around the central point, where the spring that match with incoming spark point on cap is.

I was starting on think is an electrical issue, since in my experience, carb problems are not THAT regular with THAT perfect timming/beat... exactly like a machine gun. My carb issues with iddle have been irregular, and specially keep during acceleration.

The carb is recently rebuilt, but with a TQ never knows LOL.

maybe removing and re-installing the rotor so many times, you could have bent the tab on the top of the rotor, and it's barely making contact with the cap coil wire?   bend the tab up a bit, also your observation of carbon like build up usually is normal to a certain extent, but could also indicate arching supporting the theory.  make sure there is good contact between the rotor tab and the cap. 

[RD]

nacho,
  check to see if you unplugged any vacuum hoses.  when a vacuum hose becomes unplugged, idle becomes really rough, but when you push down on the gas it will smooth out.

[Nacho-RT74]

Ok, Ill check everything easy first. Engine starts good and runs good, is only iddle problem.

The Machine gun stuff is not really a noise literally, is just the stumble stuff that makes it looks like that

Vacuum hoses... since my car doesn't have emission controls only hoses I have are dist advance, choke pull off, air diaphragms and PCV. easy to check that.

The rotor burned areas I think they are almost new... I don't remember have seen them before first time I removed it like security stuff.

I think I have to check floaters level anyway. I have noticed that brass floaters even they are mostly used and better specially for performance stuff also have noticed they bend easier than the phenolycs ( sp? ) ones. And since I'm getting oftenly some backfiring...

[Nacho-RT74]

Ok, checked and I have:

-rotor tab fits perfect with center contact on cap, I bended up a little anyway.
-dist cap doesn't show anykind of damage anywhere. Not even worn areas. everything clean.
-was daylight so I couldn't check for visible sparks around wires but didn't hear sparks jumping around...
-Dist on same position that I have had before the fail. Don't have a timming light, but since I have a mark between dist base plate and block on 0º I could say is around 10º-14º.
-check floaters level they were good. One a little bit out of adjustment but nothing to get mad about.
-found a gas deposit on the tipical place of TQ. Where bowl wells sits on lower plate. One of them, passenger side. So I'll replace the epoxy glue. For a while changed the plastic bowl for one I have theorically repaired ( same as usual, bowl wells epoxy glue areas ). This one I know wasn't perfect BUT when I had mounted, fail was different.
-engine started perfect at first try. Just a little bit down rpms that I was used to feel with choke cam up. Got black smoke on driver side exhaust while warming
-Once engine warmed, GOT SAME "FAIL". Low RPMs without move any screw ( iddle screw or mixture screws ). everything was like BEFORE get that fail. Oftenly iddle changed a little bit, but maybe becsue the plastic bowl is not perfect.

I think I can get the perfect description about the fail... maybe is not exactly the "machine gun" stumbling or sound. On haynes manual says about how get the mixture adjust. They say:
-screw out the idle screw far as possible without engine runing rough.
-turn clockwise one mixture screw until engine iddle drops a noticeable ammount and the screw out untill maximun iddle speed but not further... same to the other side with aproximatelly same turn to keep balance.

ok... this fail is like when you starts to adjust iddle mixture and getting the minimun iddle possible without running rough... is EXACTLY like that. BUT FAIL STARTED ON STREET, RIDING... NOBODY DID TOUCH ANYTHING.


I think really could it be carb now... But

[resq302]

It almost sounds like a carb issue that I had on my 70 el camino.  I started having rough idling issues and pulled the carb only to find gas puddling inside the intake manifold.  Is it possile that you have a hole in your float which would cause a flooding condition at idle?

[Nacho-RT74]

floaters are new.

YOU KNOW WHAT ? I remember now that I had a similar, not exactly, but very similar problem long time ago and was the air vent gas pump hole clogged. that was causing to much pressure gas up to carb. Those days were visible drops falling down to the venturys. now they are not visible, but...

[Nacho-RT74]

FIXED...

was the gas pump vent hole clogged with dust and grease AGAIN... but this time fail was not exactly the same. That as the reason I didn't think on that first...

I think that I have to change and aply new RTV on gas pump gasket to save that.

The problem is when I was installing the alt before I removed to get more room to clean the pump, damaged the metallic piece where to bolt screws ( damaged thread ) and broke the spark plug wires bracket located on frist bolt of exhaust manifold to head. DAMN... that kind of stuff aren't sold here. I bought a set on YO but son't want to spend shipping for that...

Do you know if on Mopar parts dealers are they still available ?

the alt stuff was already changed.

[AKcharger]

Nacho I'm having the same problem...you mean a vent hole on the fuel pump??

[Nacho-RT74]

yep... that same hole makes too much pressure on carb when is clogged. the hole is around 3-4 milimeters diameter and is on a side of top section of body on gas pump. In my pump ( ACC canadian pump ) is toward to engine.

[Nacho-RT74]

red arrow is pointing where is the vent hole.. on my gas pump is on the other side... that it could be different depends of brand as far I know