Thick Black Smoke

Discussion in 'Technical' started by MavJoe, Jun 25, 2008.

  1. MavJoe

    MavJoe Certified Lunatic

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    Wasn't quite sure what to use for a title :D.

    Anyhow I do have such an issue with the Mav, it's been sitting in my driveway for the better part of a year, up until a few months ago I had been starting it regularly, not driving it (can't because of the sticking shifter, - it's a Manual), just starting it and letting it run for a few minutes.

    It has always been a chore to start it ever since I bought it back in 02, sometimes it would fire right up (summer time only), other times I would be at it for a good five minutes or more before it finally came to life sputtering and spittin and finally running. After it finally started I would often have to apply light pressure on the Accelerator to maintain a satisfactory idle for a few minutes, if I rev'd the engine within that time frame it would spit loudly and often die, sometimes it would fire right back up other times more cranking and cranking.

    Anyhow on to the point of this thread back in February I began to notice it was taking even longer to start, to the point where it would wear down the battery, when it finally did start it would run ok for a few minutes then begin spewing thick black smoke (hence the title :)) at which point it would start running rough finally stalling, after which I could not restart it for awhile, trying to do so would wear the battery down considerably.
    Btw it also left lovely little black spots on the driveway when it's done this thankfully my landlord hasn't noticed them.

    I pulled the plugs and sure enough they were black as night all six of them equally. In addition to that a strong fuel odor was coming from the plug holes so I now I officially knew why it was belching smoke it was flooding, but I sort of figured that already. Thing is it's really flooding and I mean bad.

    It's never done this before so I figured maybe the Carb finally went or the Points did probably both knowin my luck. It's acting like the Carburetor is dumping gas so one of my theories is the Float is full of gas so it doesn't know when to ease up on the Fuel Delivery and thus the gas dumping, then there is the Points theory but after checking them they look fine though I know you can't always tell by looks alone.

    Would rebuilding the Carb fix this problem? I figured I would get a Rebuild Kit since they were cheap (AutoZone has em for $12) and just try rebuilding it myself couldn't hurt certainly beats buying a new Carb which run around $150 and up.

    I've also theorized the Fuel Pump could be putting out too much pressure but wouldn't I notice Fuel Leaks if it were doing that?
  2. Old Guy

    Old Guy Member

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    Assuming it is a 6 cyl, I bet the carb needs attention. Sitting for long periods of time with old fuel in the system, will crud up gaskets, float needles, etc. Also if the float itself has any minute holes or leaking seam, it can sink and overflow the fuel delivery. Check the choke plate for proper operation and block it open with a wooden dowel or similiar tool, and see if it will start. Drain the oil too, and see if it is contaminated with fuel.
  3. Mavman72

    Mavman72 I'm mister heat mizer...

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    just letting it idle for a few minutes isnt good for it or the plugs let alone the oil.Change the oil in it first off.(its gotta be full of gas)If you are ging to run the engine,let it run for a good 30 minutes to cook off the moisture in the engine/oil.Run it up to about 2 grand for a minute or three at about the 15 minute mark,then idle it for 15.Dont rev it right before you shut it down,that just washes the oil off the rings after shut down.A rebuild cant hurt the carb,some sta-bil in the tank of gas will help too.Gas detirriorates when it sits for long periods.The worse the gas gets the worse the car runs...Just som stuff to ponder for you.Good luck.Looks like Old guy beat me to the punch!!!LOL...
  4. don graham

    don graham Member

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    Sounds to me like a stuck needle valve or float. Probably due for a carb rebuild anyway.:)
  5. MavJoe

    MavJoe Certified Lunatic

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    Well I went ahead and bought the Rebuild Kit at AutoZone. Don't know when I'll get to the actual rebuild but good to have the kit on hand for when I do.

    I would do more then just run the engine if the Shifter wasn't constantly seizing up on me making it impossible to shift beyond 2nd Gear, heck I can't even put it in Neutral half the time without fighting with it for a good ten minutes. When I was able to actually drive it I did so, my ears were often ringing afterwards (no headliner in there and a hole in the muffler makes for a very loud interior even with the 200).

    I'm still green with Carburetors never took the time to learn them and I've long since moved on to learning EFI systems since the Saturn is EFI. If I had the time and money (can't stress $$$ enough) and the right engine in there that I want (302 preferred) I would attempt an EFI conversion like some others on here have done, but thats probably not gonna happen anytime soon.

    This will be a learning experience for me as far as Carbs go that is for sure.
  6. Bryant

    Bryant forgot more than learned

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    ya sounds like you washed the oil off the rings and cylinder walls. pull the plugs, put just few drops like mabe half a cap full of oil into the cylinders. then put the plugs back and start it. every body is right that starting and runing it only for a few mins is bad. you need to get it up to operating temp to ensure a good life for the motor.
  7. PaulS

    PaulS Member extrordiare

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    Black smoke is a sign of excess fuel. The choke could be mis adjusted, the float could be high, gasket might be torn. If you can't rebuild it yourself then get a new carb - for a 1969 model year. They don't have a lot of the mods for emission controls and the car will run better.
  8. MavJoe

    MavJoe Certified Lunatic

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    Yeah I know :90:, when it was actually running I usually did let it run for awhile, I should have been more clear sorry bout that. It's only recently with the black smoke that I would run it only a few minutes because thats all I would get out of it before it died then I had to wait for the flooded gas to clear, which since there was alot of it that took forever.

    I believe you are right on that one, the choke has been a problem since Day #1, the previous owner had it adjusted all the way lean and the Carburetor Adjustments were all screwed up (to put it mildly), granted the car got excellent Gas Mileage but it ran like crap. I was able to adjust it to run a bit better (mind you this was back in 02) but I never could get that damn choke to work right no matter what I did. The heat riser tube being broken at the manifold wasn't helping matter either, I sort of fixed that it's basically wedged on there might try some JB Weld when I get the Carb rebuilt but thats next weeks problem.

    Because the choke was always messed up the Fast Idle was too, it was either way too low or way too high, usually way too low to where if I took my foot off the gas car would stall, that made shifting into reverse from a dead stop interesting, it also effected take offs sometimes the car would lurch a couple times and finally catch and take off, it was because of this I didn't take it out in traffic :eek:.

    I was reading up about the Carter YF Carb last night forget where one of the things mentioned was the Accelerator Pump Diaphragm could wear out which would cause the spitting and the lurching, any truth to that?? As I said this is all green to me so the more I can learn before I start the better off i'll be :). In any event the kit I bought came with a new one.

    Oh I should also mention that I did have a situation where it backfired out of the Carburetor once when I had the Air Cleaner off, when I gave it some gas the fast idle cam came all the way down and the screw caught on it and before I could fix it *BOOM* sounded like a bomb going off and even got the car alarms down the street going off. Fortunatley I was not near the Carb when that happened, I quickly killed the engine and waited for the smoke to clear. This happened back in 02 as well but I wasn't sure if this might have messed up the Carburetor it was never right to begin with but I imagine that didn't help.

    Wheww sorry for the long post.
    Last edited: Jun 27, 2008
  9. PaulS

    PaulS Member extrordiare

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    You are going to have to replace the missing tube to the choke. Without it the choke won't warm up and open. The carb will never work right because there is vacuum pulling air through the tube to warm the choke. With no line there it will just pull in dirt, and cool air.
  10. MavJoe

    MavJoe Certified Lunatic

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    Oh the tube is there it's just where it meets the exhaust manifold is messed up, old age and rust took it's toll on it.

    In order to replace it I would first have to replace the exhaust manifold which unfortunatley is not possible due in part to the fact one of the bolts securing it to the cylinder head has a broken head and can't be removed. This problem occurred when I attempted to remove the Exhaust Manifold because I was going to replace it because of that tube. When I went to loosen it (the last bolt no less) *snap*.

    So I ended up wedging the tube onto the part where it broke to where it's on there but if I were to bump it hard enough which will most likely happen when I go to remove the Carburetor it'll come loose, hence why I was pondering the JB Weld. Right now the tube is physically in contact with the manifold so it should be pulling hot air, I hear ya on the dirt it's no doubt pulling that in as well because it's obviously not sealing right.

    Hmm thinking about it I wonder if I could just make the hole in the Exhaust Manifold where the heat riser tube goes slightly wider with my drill and just push the tube into it to where it's snug, won't be perfect but it'll be better then it is now, and short of pulling the cylinder head and taking it to a machine shop which I really don't want to do (and don't have the money anyway) my options are limited.
    Last edited: Jun 27, 2008
  11. PaulS

    PaulS Member extrordiare

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    MavJoe,
    you can drill the tube out of the manifold with a 1/4 inch drill. Replace it with a copper tube with an insulating sleave. Depending on how it attaches to the carb you use either a 45 degree flare and nut or a farrel and a compression fitting.
    The fresh air tube next to it or under it depending on which type of manifold that you have can be replaced the same way and tied into the bottom of the air cleaner base.
  12. MavJoe

    MavJoe Certified Lunatic

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    I managed to get the piece out finally, ran my drill battery dead in the process but thats what the charger is for :).

    Dunno when I can replace the tube though, I guess i'll worry about it after I finish the Carburetor and hopefully get it running again. I tried reshaping it with a file to fit in the hole. It fits better but not as snug as I want it.

    Next item on my to-do list is I need to track down a new Float. Very few places seem to have them available, looks like Napa is my best option there, they aren't expensive so thats good, I just hope the Napa around the corner from me has one but i'll likely end up having to go to the Main Warehouse Center across town, which is usually the case whenever I go to Napa to get parts for the Maverick. I don't know if Auto Krafters carries them (my catalog is buried somewhere) but I wouldn't want to wait that long for it anyway.
    Last edited: Jun 28, 2008
  13. MavJoe

    MavJoe Certified Lunatic

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    Oh boy does this Carburetor ever need help.

    I pulled it off the car finally and removed the Air Horn Assembly to see what I was dealing with. I was expecting Gas in the Float Bowl to spill out, not only did that not happen it was bone dry and full of Rust Colored powdery varnish. Float was bent sideways (dunno how that happened), and the dash pot is busted (I should have noticed that while it was still on the car). That would partially explain the stalling.

    Who knows what else I will find, when I get in there more I will post an update. Wish I could post pics to but no digital camera.
  14. MavJoe

    MavJoe Certified Lunatic

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    Rebuild Complete

    Finished it up last night and installed it on the car today.

    I poured a little gas in the Fuel Bowl Vent and with the Air Cleaner on cranked the engine. Took a few seconds it sputtered and finally came to life. I'm not surprised at the sputtering it has been sitting for a few months of not running. Still didn't take a whole lot of effort to start it for a change which to me is an improvement.

    Black smoke is gone and it ran good for a change, i'm not ready to declare victory just yet as it still has other issues (more on that later). After finally getting it into neutral (shifter issue i've mentioned before) I sat there listening to my squeaky clutch :D letting the engine warm up. Only took a few minutes for the choke to open and idle to slowly come down so the heat tube (messed up as it is) is doing it's job.

    I still need to tweak with the idle a bit because once it's warmed up fully it still seems to be idling lower then it's supposed to. The Idle is fine when the choke is closed and I finally got the fast idle where I want it, however since the fast idle screw is missing it's spring (probably not the right screw either) if I use the car often I have to check it occasionally to ensure it is not backing out throwing the adjustment off. Also since the Dashpot is broken I didn't bother reinstalling it, I haven't bought a replacement yet i'll eventually get around to that. Carburetor Factory basically told me I don't need it that all it does is keep the throttle from slamming shut. I can probably compensate for that.

    As for the Mixture I think thats fine though I could be wrong, I just took a shot in the dark setting that when I assembled the Carburetor. I haven't tried to adjust it with the engine running yet seems to run ok as is.

    Other issues:

    Still has an occasional Spitback issue if I floor the throttle and then let off suddenly. It did it earlier once which turned on the Alt Light for some reason (the Alt Light went off the min I tapped the throttle again).

    ALT Light, Always stays on after I start the car until I tap the Throttle then goes off and with the exception of that spitback issue above rarely if ever comes back on while the car is running. I've had the charging system tested before and was told it's functioning fine, so this is weird. I do hate that Alternator though the dash lights get real dim when I push the brake pedal esp if the Lights are on. They are also effected by the turn signal and hazard Lights, it's one of those crappy 38 amp units.

    I'm sure there is more but this post is long enough :bouncy:.
    Last edited: Jul 3, 2008

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