Larry W

Ls400 Cranks But Won't Start

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I just got the car back from having the new A/C evaporator installed (works great..ice cold again). I turned the engine off and 15 minutes later when I came back to the car it would not start. It cranks fine. The tank was 1/4 full and the temperature gauge was in the normal range. I removed the hose assembly from the fuel injection unit and sprayed in some starting fluid and it cranked right up. I drove about 5 miles to my home and shut off the engine. I tried cranking it again and it would not start. It was late so I thought I would look at it this morning. Outside temperature was 72 degrees and it started right up! I drove the boys to school and went to work. I shut the engine off and tried starting it again and it was a no start. Cranks OK. Doesn't sputter...runs perfect after starting. I did fill it up with premium fuel last night and put in some STP fuel injection cleaner. Open for suggestions. Wife did fill the car last week with 1/2 tank of 88 octane regular fuel (by accident). Do you think...?

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I just got the car back from having the new A/C evaporator installed (works great..ice cold again). I turned the engine off and 15 minutes later when I came back to the car it would not start. It cranks fine. The tank was 1/4 full and the temperature gauge was in the normal range. I removed the hose assembly from the fuel injection unit and sprayed in some starting fluid and it cranked right up. I drove about 5 miles to my home and shut off the engine. I tried cranking it again and it would not start. It was late so I thought I would look at it this morning. Outside temperature was 72 degrees and it started right up! I drove the boys to school and went to work. I shut the engine off and tried starting it again and it was a no start. Cranks OK. Doesn't sputter...runs perfect after starting. I did fill it up with premium fuel last night and put in some STP fuel injection cleaner. Open for suggestions. Wife did fill the car last week with 1/2 tank of 88 octane regular fuel (by accident). Do you think...?

have you checked to see if there are any error\check engine codes??

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Your problem has nothing to do with fuel octane rating. I've been running regular for >2 years without any issue.

I would look for a loose wire on the engine temperature sensor. Maybe they knocked it off when they were working on the AC. Since you problem is temperature related it seems maybe the ecu isn't getting proper input. As ML states this should throw a code in the ECU so you could save a bunch of time starting there.

Also could try opening and closing gas cap when it doesn't start to be sure there isn't a vacuum in tank restricting fuel pump (although I think this is more of a long shot but easy to try).

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I agree, check the coolant temperature sensor, a faulty or loose connection would confuse the ECU when starting under a warm condition in the wrong fuel map.

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i just got my ls400 two mouths ago.It past smog ran great i took it two the paint shop and had it painted but when i went to pick it up. It would start and die out right away. But if i keep my foot on the accelerator a little it would say on until i let go of the accelerator .I towed it to the house and tryed to start it again the next day. Know it just cranks and dont start. its not getting spark now ether my friend said its the igniter. any idea oh yeah its getting gas and the security system is disarm help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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i just got my ls400 two mouths ago.It past smog ran great i took it two the paint shop and had it painted but when i went to pick it up. It would start and die out right away. But if i keep my foot on the accelerator a little it would say on until i let go of the accelerator .I towed it to the house and tryed to start it again the next day. Know it just cranks and dont start. its not getting spark now ether my friend said its the igniter. any idea oh yeah its getting gas and the security system is disarm help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

First thing first, start a new thread. Bogarting into someone else's thread with a completely different problem is just plain rude.

Secondly, when you do post, try typing a little better and use capital letters where they belong so people can easily read it and be better able to help you.

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Your problem has nothing to do with fuel octane rating. I've been running regular for >2 years without any issue.

I would look for a loose wire on the engine temperature sensor. Maybe they knocked it off when they were working on the AC. Since you problem is temperature related it seems maybe the ecu isn't getting proper input. As ML states this should throw a code in the ECU so you could save a bunch of time starting there.

Also could try opening and closing gas cap when it doesn't start to be sure there isn't a vacuum in tank restricting fuel pump (although I think this is more of a long shot but easy to try).

Where exactly is the engine temperature sensor (94 LS 400)? I did open the gas cap (tried long shot) and a tremendous amount of air came out. Ready to fix this problem today. Thanks for the input. Awaiting your reply (is there a link?) Good news again is that the A/C is still "ICE COLD".

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This is really odd that I have the exact same problem as you, just not as bad. When I park my car in the sun for a while and go to start it it cranks for a solid five seconds before starting. Like you it cranks fine and runs great when started. I didn't know that the coolent temp. sensor could cause this until I read this, but come to think of it when I replaced my coolent temp. sensor a while ago I busted the clip on the litte connector, so I just plugged it in and left it without a clip. It is pretty secure and it has never come off the sensor, but it makes sense that the connection could be slightly ajar. I too have no CEL codes.

The coolant temp. sensor is located in the front, top, of the engine. To the left side of where the spark plug wires cross from side to side. I hope that helps some.

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My car always starts within a second or two of cranking the engine. I remember thinking... "this starter will never wear out if this car starts this easily". Going out to check out the sensor position this morning.

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My car always starts within a second or two of cranking the engine. I remember thinking... "this starter will never wear out if this car starts this easily". Going out to check out the sensor position this morning.

Is it possible that the mechanic did something to control box (under the dash) when he installed the evaporator? My car always ran great up until I had this part installed. Is it perhaps just a coincidence that the sensor failed right after I picked up the car? Any opinions please?

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My car always starts within a second or two of cranking the engine. I remember thinking... "this starter will never wear out if this car starts this easily". Going out to check out the sensor position this morning.

Is it possible that the mechanic did something to control box (under the dash) when he installed the evaporator? My car always ran great up until I had this part installed. Is it perhaps just a coincidence that the sensor failed right after I picked up the car? Any opinions please?

Is there a link (pictures and all) for replacing the temp sensor?

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This is really odd that I have the exact same problem as you, just not as bad. When I park my car in the sun for a while and go to start it it cranks for a solid five seconds before starting. Like you it cranks fine and runs great when started. I didn't know that the coolent temp. sensor could cause this until I read this, but come to think of it when I replaced my coolent temp. sensor a while ago I busted the clip on the litte connector, so I just plugged it in and left it without a clip. It is pretty secure and it has never come off the sensor, but it makes sense that the connection could be slightly ajar. I too have no CEL codes.

The coolant temp. sensor is located in the front, top, of the engine. To the left side of where the spark plug wires cross from side to side. I hope that helps some.

Is there a link with pictures showing how to service this sensor?

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I have a 94 LS 400. When I press the gas to speed up or pass it starts to hesitate, the check engine and traction light comes on and stays on for a few minutes then goes off. This happened about 4 times. I've only had the car since March 131,000 miles on the dash. The car's gas needle got close to E. I went to started this morning and it cranked up, and turned over, then turned off. I figured I ran out of gas. I went to the gas station and bought a gallon,put it in, still no start. Im lost can someone help please.

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"Is there a link with pictures showing how to service this sensor?"

Here is the Link

By the way, you should check if any cable was unplugged during the service. If the car ran fine before AC evaporator service, then It cannot just happen to fail the temperature sensor.

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