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Cold start problem with a 1KZ-TE

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  • Cold start problem with a 1KZ-TE

    Hi guys,

    I have a 2001 Prado Diesel 1KZ-TE. 95% of the year it will start fine but on the coldest days it has a very hard time starting. Once it has started it will be fine all day and there are no other issues with it when running. Things that have been done to it already are new glow plugs and new injectors. Tested that the glow plug relay is engaging and that it responding to the coolant temperature. It will eventually start but can range from difficult to impossible depending on the temperature. < 0 it becomes impossible.

    Next step that the mechanic is thinking of is potentially the fuel pump, but that is a obviously a very expensive job. Any advice around other simple things that might be wrong and contribute to cold start issues before a fuel pump is replaced would be appreciated. It has done 300k. Finally, do people think that a reco fuel pump will help? Are there fuel heaters that you can get that might avoid a costly fuel pump replacement?

    Thanks very much.

  • #2
    Is it spinning over at a good rate when cranking, or is it struggling?
    Cold batteries donít put out full voltage so if you only have the one stock battery and the temp is very low it may not be turning over fast enough.
    I went to twin start batteries and the difference was incredible.
    No idea why the imports have two and the Au delivered car went for one.
    The mount is all there ready to go.
    6-pot Cruisers have two batteries and a 6 is a lot easier to crank than a 4.


    • #3
      I doubt itd be the fuel pump, youd notice that when driving too and when warm. Have someone keep priming the fuel pump on the fuel filter while trying to start it, if that doesnt eliminate the issue id consider batteries as above and also check your oil level and smoking on start up in case some leakage is happening.
      Also check on that fuel primer that its not losing much prime overnight, ie dripping fuel somewhere.
      Also did you test the glow plugs were working or just the relay?


      • #4
        Common problem with Toyota's using those 1KZ motors is the fuel primer themselves like Mikey has suggested. They often get an air leak in the primer which allows the diesel to flow back to the tank especially after sitting for a while, which will mean next time you start it you have to crank it for a long time (unless you prime it first) relying on the injector pump to draw the fuel up which can take a long time sometimes not at all and is no good for the pump. Only cost about $50 on ebay so worth considering before forking out on a new injector pump.

        Another possibility is you may have a split or leaking fuel line somwhere which is causing you to lose pressure out of the lines after sitting.

        Doesn't really explain why its only on cold days but is usually a common cause for troubled starts after sitting, otherwise as Carco said you may not have enough cranking power and may need a 2nd battery set up to supply cranking power with the 1st battery (the redarc sb12 solenoid are worth looking at for this setup).


        • #5
          To confirm if it is an air leak in the fuel system, get yourself a short length of clear vinyl tubing and a 3/8" hose barb and connect it to the outlet of the fuel filter before the injector pump. It will clearly show if there is air entering the fuel pump instead of diesel.

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