91 ls400 hard to start after sitting overnight?

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:) :) - 11 Feb 2007 07:57 GMT

Hello, The car takes about 10 seconds of cranking to start in the
morning? After that it will start up instantly everytime even if it
sits for 4 hours I will come back and it starts in 2 seconds? I was
thinking about changing sparkplugs but dont know if its a waste of
money? Car runs perfectly otherwise....Thanks:)

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Max - 11 Feb 2007 14:06 GMT

On Sun, 11 Feb 2007 02:57:12 -0500, porshapower@webtv.net (:\) :\))
graced this newsgroup with:

>Hello, The car takes about 10 seconds of cranking to start in the
>morning? After that it will start up instantly everytime even if it
>sits for 4 hours I will come back and it starts in 2 seconds? I was
>thinking about changing sparkplugs but dont know if its a waste of
>money? Car runs perfectly otherwise....Thanks:)

it's not the plugs. I'm no expert but it sounds like either an idle
air control valve or leaky injectors.

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Ray O - 11 Feb 2007 16:33 GMT

> Hello, The car takes about 10 seconds of cranking to start in the
> morning? After that it will start up instantly everytime even if it
> sits for 4 hours I will come back and it starts in 2 seconds? I was
> thinking about changing sparkplugs but dont know if its a waste of
> money? Car runs perfectly otherwise....Thanks:)

With the lack of other symptoms, I doubt if there is anything wrong with the
engine.

To diagnose the condition, install a fuel pressure gauge at the injector
rail, note the fuel pressure there, and park overnight. If fuel pressure
gradually decreases, the fuel pressure regulator may be bleeding down. The
long cranking time is what it takes for the fuel pump to build up sufficient
pressure and volume to start the car.

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Ray O
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KG - 12 Feb 2007 14:11 GMT

>> Hello, The car takes about 10 seconds of cranking to start in the
>> morning? After that it will start up instantly everytime even if it
[quoted text clipped - 10 lines]
>long cranking time is what it takes for the fuel pump to build up sufficient
>pressure and volume to start the car.

If you don't have a pressure gage easily available just turn on the ignition switch and wait 10-15
seconds for the fuel pump to build up full pressure after it has set for a long period, if it
starts quickly you most likely have a leak down problem.
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Ray O - 12 Feb 2007 17:04 GMT

>>> Hello, The car takes about 10 seconds of cranking to start in the
>>> morning? After that it will start up instantly everytime even if it
[quoted text clipped - 21 lines]
> *****************
> Thank You kGbAT@msbx.net

The fuel pump only operates if the engine is cranking or running. Turning
the ignition switch to the on position without cranking will not energize
the fuel pump.

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Ray O
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St. John Smythe - 12 Feb 2007 22:46 GMT

> The fuel pump only operates if the engine is cranking or running. Turning
> the ignition switch to the on position without cranking will not energize
> the fuel pump.

I thought it energized it for about one second (if you didn't crank
immediately).

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St. John
In Pocataligo, Georgia, it is a violation for a woman over 200 pounds
and attired in shorts to pilot or ride in an airplane.

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Ray O - 12 Feb 2007 23:19 GMT

>> The fuel pump only operates if the engine is cranking or running.
>> Turning
[quoted text clipped - 3 lines]
> I thought it energized it for about one second (if you didn't crank
> immediately).

I am pretty sure that the fuel pump is only energized if the crankshaft is
rotating.

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Ray O
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:) :) - 13 Feb 2007 07:24 GMT

Hello and Thanks fot all of you for the help. I turned the key to see
if I would hear the fuel pump energize but nothing. I had a bmw which
when I turned the key it would buzz for a couple of seconds but the
lexus doesnt do this. I changed out the plugs today for good measure
and will see what it does tomorrow morning. Im still leaning toward the
IAC(idle air control valve). When the car is cold and I unplug the iac
the idle will rev up and down. When the engine is warm and I unplug it
nothing happens besides my car has a low idle when warmed up..should be
600 +/- in park with warm engine..Im at 400 in park with warm engine...
The iac is a large contraption at the front of the motor not near the
throttlebody. There are coolant lines going into as well. I pulled out
the piece that rotates(with 2 bearings on it) and am not sure if this
works or not ...but might try to replace the bearings as the iac costs
$700 for a new one....would a bad iac cause the hard start in the
morning as well??? Thanks again:)

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Ray O - 13 Feb 2007 16:23 GMT

> Hello and Thanks fot all of you for the help. I turned the key to see
> if I would hear the fuel pump energize but nothing. I had a bmw which
[quoted text clipped - 11 lines]
> $700 for a new one....would a bad iac cause the hard start in the
> morning as well??? Thanks again:)

A bad IAC can cause poor idling but it is not likely to cause long cranking
times after a cold soak. You can try cleaning the moving parts of the IAC
with throttle body or carb cleaner, and it may improve idling but I would be
surprised if it fixes the long cranking times.

If you can rent, borrow, or buy a fuel pressure gauge, you can see if fuel
pressure drops overnight. If so, the fuel pressure regulator is bleeding
down and the fuel pump has to re-pressurize the fuel lines for the engine to
start.

I would not waste time listening to see if you can hear the fuel pump
because if the engine does eventually start, the fuel pump is good. If the
fuel pump is bad, the car won't start.

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Ray O
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