LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Hard start when cold

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Old 10-04-22, 01:41 PM
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avhart
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Default Hard start when cold

Hey guys have managed to sort out most of my problems so far. Got my ECU repaired by Soarer Surgeon in NZ, got my fuel pump pressure right, and fixed my Viper alarm issue. But I am still getting a hard start problem when I try the first time in the morning. I have to crank it a few times and actually pump the accelerator before it starts but if I were to put just a small shot of starting fluid (gas) into the throttle body it starts right up immediately and runs fine from then on.

Any ideas as to what may be the cause of this? I don't think it's plugs/coil/igniter or anything electrical at all. Could it be the cold start injector? But I'm not sure if my car even has one of those. Any suggestions would be welcome. Very welcome...

P.S. although the title is "hard start when cold" I live in the Caribbean so "cold" must not be taken too literally.
Old 10-04-22, 01:57 PM
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timmy0tool
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have you tried to prime the fuel pump twice before engaging the starter? in other words, from ACC turn the key to ON for a second then back to ACC, then back to ON then START. the thought here is that the fuel pump needs to pressurize a bit more after being off overnight.

this is just for troubleshooting purposes which may point to a fuel delivery issue.
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Old 10-04-22, 02:36 PM
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avhart
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Hey Timmy, thanks for taking the time to reply. The answer to your question is Yes. I myself was thinking that if I turn the ig on and off a few times and leave it on for a bit the pressure may build up in the rails but that doesn't help. The strange thing is the pumping of the accelerator to get it going. If it had a carburetor I would understand but with EFI, not so much.

And then with just a small shot of gas through that hose in the pic into the throttle body starts it up immediately and then its all good. That also works without me having to go through the pumping thing either. It's strange. Just put a shot in the hose and it starts like nothing is wrong.


Old 10-04-22, 02:56 PM
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it seems JDM engines don't have the same dampers/solenoids/regulators on the right of the intake manifold as our USDM engines do! i wonder what they are?


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Old 10-04-22, 03:08 PM
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Yeah that's the EGR/emissions stuff. I'm not sure if it would have a bearing on my problem though
Old 10-04-22, 06:03 PM
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Toyota changed the design of the cold starting system in August 1992. The cold start injector 23260-59035 is no more used after that. Is your Celsior made before or after that? If before, you need to check the cold starting system but I'm not familiar to early Celsiors and sorry that I can't give you any specific ideas.



Lower part


Last edited by Yamae; 10-04-22 at 06:55 PM.
Old 10-04-22, 07:01 PM
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I think I'd better add the drawing of injector system after August 1992.


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Old 10-05-22, 05:18 AM
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Thank you for your reply Yamae. Now that is good info and will help me in determining if my Celsior is so equipped.

Do you have any suggestions as to what may be causing my cold start problem as well?
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