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Starting Problem 'heats Up'..


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After owning my 91 ls with 132k for a month or so, it started taking a long time to turn over when the motor was still warm. Ran perfect once it started. It would just crank and crank like bad battery terminals etc. Replaced those and then some. Did the 90k in totality a couple weeks after this started, hoping to alleviate the problem indirectly, didn't happen.

I exhausted all my recources trying to figure it out, and eventually took it to Bearden Automotive for a diagnosis, a lexus shop in Austin, TX when the car totally failed to start when it was still hot. They said some wiring was done incorrectly, and 166.00 later, the problem was/is EXACTLY the same. Thanks a lot Bearden...

The battery, alt., etc. have all been tested. Cold start injector replaced 2k miles ago. I don't think it is a fuel issue as the car runs perfect after being started. The plugs/dist/rotors are all in good condition. Even if they weren't.. it wouldn't run perfect. As it gets hottor in the TX summer, the problem is worsening.

I don't think it is the starter, but I know all this unnecessary cranking will soon destory it. So far, it has always started when the motor has been cold [not ran in last 3-4 hours], but when it is very hot outside it might crank for 3-4 seconds [feels like a long time] before finally turning over. Yesterday was the final straw, I was embarrased at a local shop after criticizing a tech's poor diagnosis on my brother's 4runner [ripping him off] when he came over and I had to tell him I didn't even know what MY problem was. After giving a few suggestions, it was very apparent he didn't either.

A knowledgable owner told me it may be related to my crank position sensor. As far as I can tell, it is routed correctly, and Bearden checked that. Can anyone else help me or throw out some fresh ideas? Does the positive cable ever erode or something? It has stumped a lexus technician and the best, arguably, lexus shop in the Austin area.

I'm making an emergency trip to Austin tonight from Houston where I am currently living to pick up my motorcycle so I will have something reliable to take to some interviews with my new boss[es] tomorrow. I've spent 50-75 hours of book labor on this car [don't want to fathom what actual hours would be, 120+?], digging all the way to the bare motor myself, and I refuse to let this ruin my virgin lexus experience.



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Gauges should be placed on the fuel injector rail and the residual fuel pressure checked. When shut down hot, the residual fuel pressure maintains liquid fuel in the rail. If the check valve in the system is faulty, pressure drops to zero and vapour lock results. Ignition can be checked very easily with an analyser to confirm it is working as it should. A bad crank position sensor should trigger a fault code. The check valve will not.

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if you want to check the starter i have a tutorial for you.

I would appreciate it. I want to narrow it down as much as possible and am far from afraid of working on the car. I'm going to try to locate which tools I need besides a fuel pressure tester if anything as well as the procedures for testing it correctly. I believe you just put it where a fuel line is, but don't know where this is on this particular car, yet anyhow. On my 300zx turbo it was easy because the fuel filter and some other fuel lines were easily accessible in the engine bay. I'm not taking that damn fuel filter off the ls400 for less than a grand unless the tank is empty. Thanks guys,


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Ive read your other post about it being the fuel pump thats been causing the warm/hot start...

Thanks for the update,ive had the same warm/hot start problem with my car since i bought it over a year ago and ive just lived with the problem up until now ;)

Same symptoms as youve talked of...Car Always starts fine from cold and if its left running then no problems.If you stop the engine for afew minute when its warm then mine always started ok but the engine idle would fall away after afew seconds then the engine would seem to miss then stop...Leave the engine for a minute or so and it was start fine and be no trouble...Ive been told it could be the idle control valve (nearly £400 over here in the uk).I didnt want to spend that sort of money to find after that i still had the same problem.

Someone said the fuel pump could be the problem,but i thought a fuel pump normally work or dont..

Glad youve got the starting problem sorted out and i will let you know i get on with my car.

Cheers chips..

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