HELP! Horrible cold starts, clicking and surging until warm

M Body General Discussion

  1. gomopar89

    gomopar89 Active Member

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    I have an '89 FA with 43,000 miles on her. She is my one and only and sits stored must of the time. I do take her out 2 or 3 times a month for extended drives. I do realize with only 43K on her she has spent most of her life sitting. Here is my problem:

    Lately, upon cold starting she will fire up within 5 seconds and then start bucking and surging until warm, about 5 minutes. There is also a loud clicking sound coming from the upper firewall. The clicks get more rapid when she about to die and lessens when the engine surges. This cycle is repeated over and over until she starts getting warm then it will level out and run fine for the rest of the day... Here is what I know:

    Choke is closing in proper position
    Carb is very clean and tight to the intake manifold
    Cold start air cleaner housing flap is working properly
    She has a new Delphi fuel pump
    New fuel hoses up to the rear end
    New fuel filter
    I only run 93 octane non ethanol fuel and use stabil because she sits
    Wires newer and look fine
    Spark plugs are properly colored when removed.

    HELP!...BudW

    89fifth8.jpg
     
  2. AJ/FormS

    AJ/FormS Well-Known Member

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    sounds like the PCV is cycling, but could be a plugwire is leaking, neither of which should cause your symptoms.

    Next time you start it, take a shop rag and slowly begin to cover the carb.One of about three things will happen
    1) the engine will smooth out, indicating it is lean
    2) the engine will run worse, indicating it is rich
    3) nothing much different until just before it stalls, probably indicating that the problem is not in the carburation but rather, that the ignition system is faulty.

    As to the possibility of PCV cycling, it could just be the result of the surging, or, I suppose, the cause of it. In any case just pinch the hose and see what happens. Also, you might as well pinch all the vacuum hose to all the vacuum operated devices, one atta time, as close to the manifold as possible, and note the results.

    Surging is usually rich, but if it goes away when warm then more likely it is lean. I'm guessing the metering rods are jumping up and down in response to the changing vacuum.

    If the heat crossover under the carb is plugged, the carb/ intake will be slow to warm up. It may be that the carb is set right, but the fuel is puddling on the manifold floor, causing a lean condition. The fuel will also stick to the port floors and walls. Then it can happen that a thin sheet of fuel lets go, just like rain on your windshield, it flies into the chamber... and you guessed it, causes a momentary rich condition. Just shut it off in the bucking stage and shine a light down onto the plenum floor. If it shines back at you, the floor is wet. Now you just have to figure out why this is so.
     
    Last edited: Mar 20, 2019
  3. gomopar89

    gomopar89 Active Member

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    AJ/FormS - Thanks for taking your time to respond. I have the next two days off, so I will be checking it out...
     
  4. AJ/FormS

    AJ/FormS Well-Known Member

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    Here are of quick and easy procedures
    1) remove the gas cap. If the tank venting system has failed, the engine will go lean shortly after start-up, depending on how full the tank is.
    2)With the fast-idle cam up on the highest step, and the engine up at least to1800 rpm, slam the choke blade as closed as it will go. Then as the rpm slows down to maybe 1000, open the choke again before the engine stalls.Repeat several times.
    What this does is move the vacuum up from the intake to just below the choke-blade. And increases it from the normal value of 15/18 inches, to 24/25. The high vacuum up here now pulls on the low-speed circuit really really hard, and usually vacuums up any dirt caught in the air bleeds. This restores the circuit from rich running to normal .
    3) in more stubborn cases;with the engine off,remove the idle mixture screws and blow compressed air into the holes, in short bursts. This will blow dirt out if the low speed circuits similar to the previous procedure, but in reverse.
    4) with the engine idling,pinch off the fuel supply, and wait. As the fuel level in the bowl drops, this will tell you if the fuel level is right, wrong, or very wrong.
     
  5. Mr C

    Mr C Well-Known Member

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    On your firewall up top by the wiper motor...there should be 2 vacuum relays. They are black, have a vacuum lead with a sponge filter on the tube fitting and an electrical connection on them. I bet that is what is loudly clicking...something tripping them or leaving them stuck open...vacuum related. And we all know how a car runs with a vacuum leak.

    I wish I had my FSM handy, but I'm still unpacking from a recent move. I'm not certain what those do.
     
  6. BudW

    BudW Moderator Staff Member

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    Sorry, late to the show. I’m way behind on my forum reading/responding.
    A nice looking automobile you have there!

    Living in Daytona Beach, your cold weather equipment (heater on driver’s side manifold, the short vertical duct to air cleaner, the air cleaner flap, temp sensor on air cleaner and vacuum hoses associated with that system) will never come into play. You could plug the port on carburetor and never know the difference – unless you tried to start the car when it is below freezing outside, which it doesn’t sound like you are doing.

    The two most likely scenario will either be choke related or vacuum leak (or both).

    To check for vacuum leaks is easiest to get a flammable aerosol spray of some sort. Carburetor cleaner or starting fluid both work – but others do as well. Avoid spraying towards the air cleaner throat and spray in short bursts. Also limit the amount sprayed in direction of the distributor cap (for obvious reasons) as much as you can.

    If you have a vacuum leak, then engine will be running lean. Any additional fuel will cause an immediate engine speedup (not massive but it will be noticeable rise). Possible vacuum leaks are intake manifold to cylinder heads (both sides), carburetor base gasket, any carburetor gasket, and all vacuum hoses – even those on firewall and on inner fenders.
    A sticking PCV valve and/or leaking vacuum brake booster can cause a huge vacuum leak – but generally both do not stop when engine is warmed up.

    The PCV valve is to be replaced every 30k miles – but hardly anyone does it. If valve gets stuck open, it will make for a rough running idle (same cold or hot engine). If valve gets stuck closed, then the vacuum hose is in risk of collapsing (noticeable when engine is running, if air cleaner of off or sat aside), for hose would like if you took a garden hose and pinched it with fingers (a flat oval shape).

    Being it is acting up when cold, I suspect the choke bi-metallic spring, the choke pull-off and/or carburetor linkage adjustments might be the most likely suspects. The bi-metallic spring gets rusty over the years and will kinda stick in a mid-position. Generally replacing that spring (or choke thermostat assembly, making sure the choke pull-off works and all carburetor adjustments fixes most cold-start issues. It is common for most choke springs to fail after 10-15 years.
    CT Choke Thermostat.jpg
    Choke Thermostat
    Choke Pulloff 6280.jpg
    Choke Pull-off for Holley 6280 (2-bbl)

    I wouldn’t be worried or concerned about the clicking noise, for the computer is trying to compensate but can’t.


    The choke valve position matters all the time – but when engine is hot, it will be wide open (car off). When cold, and engine off, it will be closed. When engine is running it can be in any position (usually more closed than open) and is not a good gauge to go by to determine if choke is working or not. Generally, a really small change in the choke valve angle will make a huge difference on how it runs and sometimes it defies logic.

    If you have a handheld vacuum pump, you can test the choke pull-off. It should move and hold position (ie: not leak out vacuum). If it won’t hold a vacuum and/or won't move with vacuum applied, change it.

    Another possibility – but sense it only acts up when cold, I don’t think applies here, and that is carburetor fuel level being too low or too high. Generally, this doesn’t affect engine operation if engine is hot or cold.


    To recap, I would first check for vacuum leaks and fix if any are found. If nothing, then I would obtain a new choke thermostat spring (or choke thermostat assembly), as well as check all carburetor linkage adjustments (8 different adjustments, if I recall correctly). Having access to either an FSM (Factory Service Manual) or to a carburetor kit instructions will be invaluable.

    Let us know how things went.
    BudW
     
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  7. JLN5thAve

    JLN5thAve Well-Known Member

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    All of the above - now something that I will add, I have a problem with my overflow, or bleed off from my fuel filter. Was causing similar issues, and was even flooding it to the point of killing the engine while driving. A clamp was placed on that hose as a last resort not knowing what else to do, and bam - she runs like an ape of the striped variety.

    Side note, I still do not know what is causing the issue, but the symptom and problem is fixed inadvertently.

    Edit - That car is a beauty - same color as mine but the paint isnt weathered. Nice to see one kept up.
     
  8. BudW

    BudW Moderator Staff Member

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    This might be best left to another thread (to leave Gomopar89’s thread dedicated to his concern/question).

    A question I have is: which hose did you clamp off?

    Your car should have a fuel filter with 3-fittings. Two are 5/16” and third is ¼”.
    Fi pg3499.jpg
    The filter is located behind the alternator and sometimes it helps to either remove the alternator or loosen both mounting bolts, remove the drive belt, then remove the outermost bolt (the small bolt with ½” head) and twist alternator up and out of the way.

    The smaller hose/line sends some of the fuel back to the fuel tank but its primary purpose is to prevent “vapor-lock”. For those who not heard of that term, some engines run so hot, the fuel turns into vapor before it gets to the carburetor. This occurs more often with cars from late ‘60’s to early ‘70’s. By having a small restrictior made into the filter (at end of the ¼” fitting on filter) purges the fuel vapor before fuel arrives at the carburetor. It actually does a decent job eliminating vapor-lock – but it does also present a few other potential problems.

    If the restriction on the small port of filter is missing or plugged can cause people problems.

    The fuel pump puts out 5.75-7.25 PSI. It is rare for a stock fuel pump to put any more than that. Even with the filter “restrictor” is stopped up (or missing) or a 2-line filter is installed (bypassing the return line), will not affect the pump pressure amounts.

    If carburetor is flooding, the first thing that comes to mind is the black plastic carburetor float has “sunk”.
    The second thing that comes to mind is the float level is set too high.
    Your ’88 will have a Holley 6280 carburetor – which isn’t too difficult to rebuild (maybe a 3 or 4 out of scale of 1-10). I think the likelihood have having a bad float is really high.
    BudW
     
  9. gomopar89

    gomopar89 Active Member

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    UPDATE: Once again thanks for all your replies. The last two times(over 3 weeks) I took her out for a drive, my initial cold start troubles have not occurred...go figure? She fires rite up and warms up just fine. Aside from the throttle tip in sag, she runs okay. I included a pic to show off my beauty! One of the last made at the iconic Kenosha plant. 89fifth15.jpg
     
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  10. Aspen500

    Aspen500 Well-Known Member

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    Nice car! It looks like brand new in the photo.
     
  11. BudW

    BudW Moderator Staff Member

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    Sometimes water gets in the fuel and it only takes a drop or two to cause issues.
    BudW
     
  12. DCAspen

    DCAspen Well-Known Member

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    Nice looking clean ride.
     
  13. gomopar89

    gomopar89 Active Member

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    Thank you! I know I'm getting off topic. I found this old girl,in the Tampa Bay area, almost 3 yrs ago. She was delivered to Brandon Chrysler Plymouth in Brandon, FL. One owner, garage kept with only 42K original miles. She was part of an estate sale and many thing were replaced and refreshed prior to my purchase. I got them down to $1600 and the rest is history.
     
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