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Thread: Cold start problems

  1. #1
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    Talking Cold start problems

    Hello--I have been having cold start problems. This is a relatively new problem. 1972 with stock SU's. When it did start, it was running very rough like on 4 or 5 cyls. When it was starting it would turn over fine but it would sort of sputter in starting. Sort of a kachung, kachung, kachung, sputter, die, several times until it started and then it would barely turn over. When it did catch it would run very rough. Got it to a shop and they found that the front choke was stuck and the front three plugs were badly fouled. Unstuck the choke and replaced plugs with 6 new NGK's. Tweeked the carbs and got on the road and the car ran sweet. The morning after it started all over again, however when it finally did get started, it ran smoothly. Checked the plugs and they all were a uniform dark copper color. Any ideal what is causing this?

  2. #2
    HLS30165540
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    Pull your plugs after the car has sat overnight. They should be the same dark copper or dark grey color. And they should be dry.

    Sounds like maybe your valve seals are shot. Oil leaks down into the combustion chamber and fouls your plugs. It runs fine after all the oil burns off. Speaking of burning oil. How much oil does your engine use, do you have to add a quart every 1,000 miles or so?
    The 1973 240Z 165540 Slightly modified. L28, 5sp, cam, headers, MSD 6AL, power windows, power door locks, leather seats, custom this and custom that.

  3. #3
    Deftly daft Alfadog's Avatar
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    Should the L24 start first time when it's cold without the choke?

    If so, arghhhhh!

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    The chokes are the first area to check.Make sure both are working correctly.I had one that had slipped on the wire once so I was trying to start with only one choke.It cranked but it was an effort.The other is the fuel pump.Some Z's had mech,some electric,some both.I fought the start problem with an electric as it would allow the fuel to drain back in the tank over night.After wearing out the starter in the morning it cranked fine all day--until.I haven't had that issue with mech.but I could see it .All it would need is a bad check valve.Then your fuel could run back to the tank like removing your lips from a drinking straw.A clear fuel filter and see how long it takes to fill it in the morning would be a good test. Havefun!! Daniel

  5. #5
    beandip beandip's Avatar
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    Smile cold start troubles

    I agree with Daniel . Most likely the trouble is with a choke that is sticking or out of adjustment. Try this are you familiar with the adjument of the SUs , if not , there is a rubber line that runs from the float chamber to the adjustment "knob" . that "knob " is the rich-lean adjustment for the fuel mixture and it is also connected to the choke linkage because when you pull the choke lever it is supposed to lower this "knob and the shaft that it is connected to. So when you push the lever to turn OFF the choke , feel under the carb and see if this knob all the way up by pushing up on it NOT turning it. some times the thing will stick down slightly and that will flood a lot of gas into the engine. Now if the thing is sticking check the hose and see if it is stiff or brittle , this can cause the choke to stick. If the hoses are bad get replacement hose from NISSAN the hose at the parts store is not soft enough. Z thearpy has the hose also. Just some info. this adjustment knob ,for lack of a better word, is the adjuster for the gross jet and the main source of fuel to the engine so when it is lowered it causes the mixture to richen as the meatering needle that closes the jet opening is moved out of the jet and much more fuel enters the engine.

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    Beandip's info is good except for two corrections.The knob on the carb bottom does NOT move.The jet slides in and out of it as it is like a doughnut.The gross jet is an aftermarket product that replaces the factory needle type fuel delivery jet with round ball bearing type.Sorry for the correction bean dip but, I would hate for Zwolley to go in search of the wrong parts. Have fun!! Daniel

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    Talking Thank you EScanlon

    It was the chokes. The cable was very dry and chokes themselves were stuck. I took it to MB Anderson and he got it running purrrrrrfectly. Starts now with no problem.

  8. #8
    Supporting Member EScanlon's Avatar
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    HEY! How'd I get involved here? I'm just an innocent by stander (and beandip you stay out of this one).

    I suppose that due to M. B. Anderson's name showing up that I recommended him at one time. I concur, the guy is a genius with them.

    Around Clark County, when I was driving around with my Z looking for odds and ends, just about every car part store, or gasoline service station would recommend M.B. Anderson for the work on my car.

    Now let's keep him busy enough to stay in business, but not so busy that I don't have access to him.

    Cheers, and glad he got you running well.

    Enrique

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    Default Long time ago

    I think it was my second post on this site when I asked for a good SU doc in the Portland area. You recommended him.

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