Engine dies - weak spark ?

Interior and Electrical

  1. Toro67

    Toro67 Well-Known Member

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    Hi Fellow Mopars

    I wrote in this forum earlier in the year about a cracked ballast resistor causing the engine to die when put in D or R and attempting to drive. No problem starting or revving in P.
    The resistor has been replaced, but the problem is still there :(
    Since the resistors´ job is to protect the coil from overheating I was thinking that the coil might be damaged too ? I may have been driving with the cracked resistor for some time without knowing.
    Last year I did a lean-burn deletion and had this Summit kit installed: Summit Racing® Electronic Mopar Distributors SUM-851003
    After the current problem came up I ordered an MSD blaster 2 - part no. 8202. It comes without a ballast resistor.
    The question is: Can I install the MSD blaster
    1 -with the current resistor ?
    2 -does it not need a resistor at all ?
    3-does it need a specific MSD resistor ?
    Or is this not the problem ?
    I have tried looking at Q&A at Summit but nothing clear comes up.
    Any good advice is appreciated - I am not an elctrical wizard, but the car ran fine all last year before the resistor cracked.
     
  2. Oldiron440

    Oldiron440 Well-Known Member

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    I would go over your wiring and then check for voltage at the correct connections before and after your splices. ecudia.jpg
    Why are you not using coil provided in the kit?
     
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  3. Toro67

    Toro67 Well-Known Member

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    I am using the coil provided with the kit, but I suspect it might be damaged since I have been running with a cracked resistor for an unknown period of time.
     
  4. Oldiron440

    Oldiron440 Well-Known Member

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    You can buy the resistor at napa.
     
  5. Toro67

    Toro67 Well-Known Member

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    Yes, but which resistor should I buy ?
    The one that came with the kit (and cracked) was a standard 1,5 Ohm, and I replaced it with a similar 1,5 Ohm.
    Should I get the one that comes with an MSD blaster 2 coil so I can test that option ?
     
  6. Toro67

    Toro67 Well-Known Member

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    Just measured the voltage before/after the resistor: 11,5 V entry and only 6,3 V goes to the coil.
    Isn´t this a bit too low ? As far as I can read it should send 8-9V to the coil.
    Update: With the engine running - 13,9V into the resistor and 7,5V out to coil.
    Still a bit low ?
     
    Last edited: Aug 25, 2019
  7. Oldiron440

    Oldiron440 Well-Known Member

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    What happens when you slip the new coil in, does it run then?
     
  8. Toro67

    Toro67 Well-Known Member

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    The MSD coil states it is to be used with a 0,8 ohm resistor. I only have the 1,5 ohm right now.
    But I guess it can´t damage the coil as long as the resistance is higher than it needs to be ?
     
  9. Oldiron440

    Oldiron440 Well-Known Member

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    Napa will have the other resistor, I'd try it with the coil you have now.
     
  10. Toro67

    Toro67 Well-Known Member

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    Sounds like a plan. I will get the 0,8 ohm MSD and try them as a set.
    I just swapped the coil for the one that came with the Summit kit just to measure it.
    It was on the car when the old resistor cracked, and it must have had an impact on it. When the car is running the output to this coil is only 5,0 V..?
    When I swap back to the other coil (still not the MSD) I get 7,8 V to the coil + side.
    I thought the resistor would come out with the same voltage regardless of which coil was on the receiving end.
     
  11. Toro67

    Toro67 Well-Known Member

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    Went down another path and ran a separate ground wire from the ICM to the firewall.
    Many threads mention the ground connection on the ICM is weak and could be causing trouble, so I re-sanded it and ran the extra wire for good measure.
    It seems to work :) Just ran a succesful 2-mile test run but had to return to base since the fuel gauge is now showing empty... Longer test tomorrow.
     
  12. AJ/FormS

    AJ/FormS Well-Known Member

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    As for a cracked porcelain resistor; that crack means nothing; it doesn't even have to be there at all. The working part is the resistor behind it and as long as it supplies the right voltages to the other components, then it is working fine. I have seen many cracked and broken resistors in which the car ran just fine.
    Just like ECUs with the goop running out of them, making your apron look like crap; the cars run just fine like that.
    Stalling on the P/N shift into gear is usually a too high idle-speed that is covering up another issue. When the engine sees the TC there is a semi-instant drop in airspeed thru the carb and with it, a loss of fuel, so the engine stalls because of the covered up issue, or stalls when you give it gas.
    But if the idle is not high,and the car continues to run after the shift into gear, and doesn't stall until you give it gas, well then; there is a very good chance that your accelerator-pump needs tuning or the plunger is just not working right. This is especially true if the idle speed is too slow.
    The accelerator linkage has to trigger a fuel squirt the very instant the gas pedal is calling for power. Not a dribble, not a fuel-slug. Just a nice steady stream smashing into the back of the throttle valve.
    To do this, the linkage has to be properly adjusted, and the delivery circuit must be free of restrictions... other than the checkvalve system under the squirter. But most of all the plunger diaphragm has to be in good working condition.
    If you have turned your curb-idle speed down,.......................... for some reason, then you HAVE to readjust your pump linkage in compensation.
     
    Last edited: Aug 25, 2019
  13. Toro67

    Toro67 Well-Known Member

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    Hi AJ
    The car will shift into D/R without stalling and also rev high in P without hesitation. The idle speed is normal and very stable.
    The problem came when I tried to accelerate in D or R - then it would stall. Could this still be the accelerator pump ? (What does the Plunger do ?)
    I have looked into the carb when pressing the throttle and it seems it delivers fuel when it should.
    I had a lean-burn deletion done last year, so the carb has some blocked vacuum lines no longer in use. I was thinking about replacing the carb with a pre-lean burn type, but the workshop said there was no need for it.
    If I wanted to fine tune the accelarator pump; how can I do this ?

    What do you mean by TC ? (I live in Denmark, so english is a second language to me :)
     
  14. AJ/FormS

    AJ/FormS Well-Known Member

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    TC is Torque-Convertor.
    When you ditched the lean-burn computer; did you keep the same distributor?
    Hi-rev in P means pretty much nothing, as there is no load on the engine.
    Oh yes I see
    Well then how much Idle-timing are you running?
    If more than 10 that may be your problem. Your throttle blades may be too low on the transfer ports.

    sum-851003_ml.jpg
     
    Last edited: Aug 25, 2019
  15. Toro67

    Toro67 Well-Known Member

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    Hi AJ
    Thanks for your info :)
    I will check the adjustment of the linkage.
    The plunger diaphragm was changed when the lean-burn was removed so it should be ok.

    Idle-timing ? Not sure what this is...

    Here are some pictures of the carb - maybe that be will be useful.

    IMG_5080.JPG

    IMG_5081.JPG
     
  16. AJ/FormS

    AJ/FormS Well-Known Member

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    Is that the lean-burn carb that was originally on the engine from inception?

    Lean-burn carbs are not set-up for vacuum advance; there is no spark-port on it. It appears that your vacuum advance can is plumbed directly to the manifold vacuum. This will add whatever timing is in the can, to the base timing, unless you disconnect it to set that base idle timing. The thing is, if you did not disable the Vcan to set the base timing, then two things get fubared; as soon as the manifold vacuum drops the Vcan drops out and the timing goes way retarded, and set like this, the transfer slots will be starved for fuel. You will have had to crank the mixture screws waaay rich to keep it running.
    But on the off chance that you DID in fact set the base timing with the Vcan defeated, then: whatever you set the Idle-timing to is probably not gonna be enough. But if you set it to the factory TDC to 5* advanced, then set the idle speed, then attached the Vcan hose back up, to manifold vacuum THEN; the idle speed would have jumped up several hundred rpm, as the Vcan advanced the timing. Of course then it follows that you would have reached over and cranked the curb-idle screw out, which promptly dried up the transfers, and in compensation, you richened up the mixture screws. And so you end up with the same sorry state of affairs.
    Like I said, the Lean-Burn carb is not set-up for vacuum advance. If you want to keep it, you will have to install a spark-port in the proper place. And I highly recommend that you do. This involves figuring out were to put it, then drilling a hole and slipping in a metal pipe and sealing it, plus you have to mechanically prevent it from falling into the engine. The best way to do this is to borrow a non-LB carb to copy where the factory put it.
    Until you get this done, I recommend to; if I'm right about the Vcan getting full manifold vacuum, to not use the Vcan.
    But if I'm wrong, and the Vcan is indeed plumbed to a spark-port that I don't know about, lemmee know, and we'll go down that road.
    >The other thing you have to do is make sure the fuel bowl is seeing atmospheric pressure, any time the engine is running. There has to be a bowl vent, and the closer to the bowl the better.
    Here's some useful chit:
    >A sparkport has no vacuum on it at idle, and will not begin to pull vacuum until something like 1500 rpm or higher. The maximum vacuum that will appear there will be close to the same as a simultaneous reading from the intake itself, beginning at perhaps as early as 1800rpm.
    >This is unlike a venturi-vacuum port which I don't think can generate that much vacuum, but it starts pulling almost right away.This port if you have one,is always a very small pipe, the smallest pipe on the carb, and it is located well above the butterflies, and usually on the passenger side. It is only used to signal something, usually the carbon canister. It could be the one that I see you have capped there by the choke.. Don't use this for vacuum advance.
    Then I have some comments;
    > the PCV system needs to have the hose running to the proper port, usually on the front of the carb, and to the underside of the butterflies, where it discharges into the airstream that has fuel already in it. If you bring it in the backside, you will be feeding the rear 2 cylinders extra air.... and they will go lean which is not a good thing, and impossible to properly tune for..
    >make sure NOTHING touches the throttle cable nor the KD mechanism. And make sure that KD spring is properly anchored at the rearend of the KD rod and not to anything stationary on the engine, which would tend to pull the throttle open, which would be a bad thing.
    >I see you have dual throttle return springs which is a good thing; however, make sure each one is capable by itself, to close the throttle in adequate manner.
    >It looks like your top radhose has gone soft and is about to blow.
    >Make sure the choke blade hangs vertical after engine warm-up.
    >If you still have the charcoal canister, I would make it/keep it, operational. It costs you nothing in terms of performance, and since your engine would be recovering fuel that would otherwise be vented to atmosphere, keeping it could contribute to better fuel economy; besides the carb is calibrated to see it.
    >As for the EGR system; a properly functioning system costs you nothing in terms of WOT power, and may or may not affect your fuel economy. It may or may not improve Part Throttle performance. Since yours is gone, and as long as it is legal in Denmark to not run it, I wouldn't go looking for one.
    And some questions;
    >Firstly, what is that "hose" that runs diagonally across the engine from the driver's side front to the passenger side at the rear, under the throttle cable.
    >Secondly; I see a hose-nipple on the intake just in front of the distributor;is that open? What is it's function?
    >Third; does your coil output wire run alongside any wires going to the plugs? If yes , this might be bad. It needs to be extracted out and separated at least two inches from all plug wires. When running alongside, it is possible that the hi-voltage in it can induction-fire an adjacent plug.This would be very bad. The wire can cross over any plugwire at or near 90*, no problem, even touching it.
     
    Last edited: Aug 27, 2019
  17. Toro67

    Toro67 Well-Known Member

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    Yes the carb is the original lean-burn carb. I think it´s a Holley 2280.
    When the mechanic did the lean-burn deletion he did say that the vacuum for the advance was weak but he had made it work anyway. Don´t know what he did, but he said the carb was fine and there was not need to change it.
    From what you say it seems best if the carb was changed to a non- lean-burn type. ? I thought of this earlier, and BudW came up with a number of alternatives. But since the car was running fine at the time I never got around to it.

    Questions:
    1 The hose is a heater hose.
    2 I think it is the hose going to the brake booster - see picture.
    3 The coil wire runs alone from the distributor to the coil which I moved to an upright position on the firewall. It was originally lying down on the intake manifold.

    IMG_5085.JPG
     
  18. AJ/FormS

    AJ/FormS Well-Known Member

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    Thanks for the additional pics.
    >That heater hose has no business being there; IMO it is a disaster waiting to happen, with the throttle cable being right there. I would route it down the passenger side, where it belongs.
    > the thing I thought was a nipple appears to be a temp sensor
    > Good on moving the coil; but Mopar coils, as far as I know, need to run horizontal for internal oil-cooling.
    None of these things are the source of your problems.
    Get the engine warmed up and idling, then take the hose off the Vcan, and install a vacuum gauge in it.
    Now, slowly begin to rev up the engine. Stop when you hit 2500 and return to idle. Observe the gauge as you do this. When you hit about 1300 to 1500 you should see about 4 inches vacuum there.By 2000 to 2500 you should see within 1 or 2 inches of manifold vacuum.
    If you don't get these numbers or very close to it, install the proper sparkport or go get a non-LB carb.
    Ok next with the v-can defeated rev the engine up to around 2200, using the fast-idle cam. Then reconnect the can. The engine should rev up about 300 or more rpm. Try it. If it doesn't rev up,then either the Vcan or it's supply port is not working, or the internal adjustment inside the can is too tight. Or possibly the base timing is too far advanced, but I doubt this.
     
  19. Toro67

    Toro67 Well-Known Member

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    Well, I can move the heater hose, but I need some professional help with the other checks. I will try and find a local Mopar guy and see if he can help.
    Thanks a lot for your input - I think I will prefer to find a non-LB carb and start over :)
     
  20. BudW

    BudW Moderator Staff Member

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    These pictures show how all the hoses should be routed on your (no A/C) car. I did install (blue) silicon heater hoses (which are quite pricy and not needed for most people) – so you can disregard the color of those hoses – but all else should be correct.
    20190910_150604r.jpg

    20190910_150613r.jpg

    It appears you are missing the heater hose bracket (yellow arrow, top picture). Here is a eBay listing for one Fits Heater Hose Bracket 70 71 Up Duster Charger Dart A B body 318 340 360 | eBay but there are outer sources for it, as well. Just look for small block heater hose bracket. It doesn’t look pretty but it gets the job done. I’m not sure why you are missing yours, though.
    Annotation 2019-09-10 175848.jpg

    One small difference/feature you have on your car that I do not, which is a hot water cut off valve (red circle). My heater core has hot water going through it 100% of the time. Yours does not, depending on which setting you select.
    untitled.png


    Your car originally came with a Carter BBD. You currently have a Holley 2280 on your car – which some of FMJ’s did come with. Your existing carburetor should work fine, once you get the vacuum advance hose hooked up correctly and get correct choke. The Holley 2280 and Carter BBD choke rod are different lengths. It appears someone bent your rod to “make it fit”, which is not a good idea. The choke rod should be straight (like mine, below).
    IMG_5081m.jpg
    The black box shows how bent your choke rod is.
    The white arrow is the correct port to hook up your vacuum advance hose to. Just pull this existing hose (shunt) off and plug hose to distributor into.

    I do recommend getting a new 318 choke thermostat for a Holley 2280 (like this eBay link Fits Heater Hose Bracket 70 71 Up Duster Charger Dart A B body 318 340 360 | eBay ). A Standard (brand name) CV189 will work (www.Rockauto.com has it, if your local parts house can't get it) or Dodge 4095339.
    Unrelated to the choke rod being bent, I do highly recommend changing the choke thermostat every 10-15 years because the bi-metallic spring inside quits working like it should. That should help with drivability some.
    Once you get your ignition problem and choke fixed, you might find your carburetor is working fine.

    20190910_150636r.jpg
    With my air cleaner still attached, this is a picture of my Carter BBD. The white arrow is the vacuum advance hose. You can see the choke rod is straight, in this picture. The hose marked with a yellow "X" is misrouted a bit, and I should fix that.