Wont Start After Running For A While

[jgresham]

Hey guys, i have a 94 ls400 and love it but lately after i drive it for a while after i shut it off it wont fire back up it cranks fine but nothing. Today i went to the bank about 10 min drive shut off the car went in came back and it wouldnt start. After 15 min and turning it over about 10 times it started up fine. it was really hot out today should that matter? After sitting for a couple hours or mornings when i go to work it starts fine? I recently had the alternator changed and thats when it started. It gave me code 13 and 25 can anyone help??

[landar]

Welcome, jgresham. Your issue may well be heat related. Now code 13 and 25 are seemingly unrelated in my thinking. Code 13 is "RPM signal 2" and code 25 is "Air-flow ratio lean". And indeed, you *may* have several issues. The air-flow being lean could be a MAF sensor on the fritz or a leak in the air intake duct work. You might have to get in and inspect for cracked rubber or hoses.

The RPM signal 2 could be a cam sensor going bad. Especially in the heat. I have read that the timing belt can stretch or be off by a tooth and also cause this code.

How long has it been since the timing belt was replaced?

[jgresham]

Timing belts were replaced 2 years ago..again when I got home it sat for 2 hours, had to run up town it fired right up. Got up town realized I forgot my wallet shut car off ran in came back out and it won't start again. Its like everytime the engine is hot it won't start. Went on a 2 hour drive 3 days ago not one glitch till I turned it off took almost 2 hours to start up after that trip

[jgresham]

I've heard it could be vapor lock, bad vacuum line, and fuel pressure valve does anyone have anything to offer?

[landar]

I've heard it could be vapor lock, bad vacuum line, and fuel pressure valve does anyone have anything to offer?

Well, I can only offer what I would do if faced with the same situation. When it did not start, I would immediately check for spark. If that were present, I would check for fuel and go from there. If you can narrow that path then you can start to figure it out. Otherwise, its a crap shoot of wild guesses and "thowing" parts at it. With fuel, you can just buy a can of starter fluid and keep it handy. Spray a reasonable amount (maybe a second or two of spritzing but don't over-do it) into the air intake snout. If the engine even hints of coming alive, its a fuel delivery problem. Else, probably spark. If you are uncomfortable with any of this you should probably seek out a good mechanic.

Can you check it for spark when it refuses to start? You might also want to check for spark when it is running correctly so that you have a good/bad comparison to contrast.

[jgresham]

honestly i do not have clue how to check spark on this car. Is it hard?

[landar]

honestly i do not have clue how to check spark on this car. Is it hard?

Hard is a relative thing. It does not seem hard to me but might for someone else. Now "Pain" is more descriptive. :)

You will need to remove some covers to gain access. I would be checking for spark at the distributors just to make sure that the coils were firing. There are two coils, each feeding the center wire of a distributor. You could pull that wire and set it within 1/4 inch of the block to see if you get an arc. You can study these tutorials to get an idea of what the distributors and wires look like and what covers would have to be removed to gain access. Of course, you would remove the plastic stuff and leave it off while you drive so that you can gain quick access when it will not start. Honestly, this is perhaps a job for a more experienced DIY'er but if you have a desire and want to tackle it, there is much satisfaction and cost savings. And if you want to do more yourself, there is a website with a LOT of good step-by-step tutorials.

Again, if this all seems too daunting, seek some professional help (for the car, that is).

Here is the link -> http://www.lexls.com/tutorials/ignition/

[WeSki]

I'm having the same trouble or very close to it; did you ever find a solution?

I'm driving a 1994 LS400 with 145k miles.

Here's my story

About 2 weeks ago after about 20 minutes of hwy driving, at a stop the car stalled, turned the key and it started right up. Over the last 2 weeks the car has stalled at least once a day and each time it takes longer to start back up. The battery is strong and cranks the engine over with no trouble. After cranking the engine for about 10 seconds the engine maybe fires a couple cyclers then dies. Crank it for another 10 seconds and it will pop over again but won't start. A week ago 3 or 4 ten second cranking it would start up but now after 5 or 6 ten second cranking it won't start at all. I have to let the car cool down for 3 plus hours and then it will start and run like nothing happened. Also after a couple 10 second crankings you can smell a lot of fuel fumes and no, I'm not pressing the throttle while trying to start the car. The car runs noticeable better in the morning when it's cold and begins to run a bit on the ruff side after engine has reached temp and has run for about 20 minutes.

All comments welcome.

Prostar

[Exhaustgases]

The original post with the RPM code is very likely a bad crank position sensor. Most heat related start problems are either that or igniter.

And you need to check the codes and report back.

http://www.lexls.com/tutorials/intro/codereading.html

[sha4000]

Definitely check for codes as has been stated. Here's a thread concerning the 95-96 models that could be relevant so give it a read.

http://us.lexusownersclub.com/forums/topic/15699-9596-ls400-low-idle-engine-dies-and-jerking-thre/?hl=engine+stall

[VBdenny]

Don't rule out the Idle Air Control (IAC) as the problem. The IAC is an electronically controlled valve located near the throttle body which controls the airflow during start up. As cars get older, especially if using discount gasoline, they tend to gum up which can cause problems similar to those you mentioned. The cheapest thing to do to try to fix it is to go to your local auto parts store and buy 2 bottles of the 10 dollar complete fuel system cleaner, the concentrated stuff. Don't try to save a few bucks and buy the $4 o r$6 stuff. Pour that it and fill it up. Go out and drive around and floor it good several times. If after a few days it isn't better then you have a problem. If not you'll be lucky and it only cost you 20 bucks.

Glad to have you here.

denny

[Exhaustgases]

Hmmm if it does run and starts goofing up when it warms up sounds like the engine coolant temp sensor, its fairly inexpensive and not to difficult to change.

[billydpowell]

Yep, I would replace the temp sensor first and go from there

[jfoj]

This is what solved a simliar 20 minute stall and no start problem on a 1993 LS400 that I was working on.

Found all the info about bad capactors in the ECU, found some leakage and decided to replace the capacitors and hoped this soled my problems. It did not solve the problems.

Then I moved on and reinspected the ECU VERY carefully. I found 1 surface mount resistor that appeared to be discolored and like it had leakage a bad capacitor, but it did not have any capacitor near or above it.

Brushed this resistor off very well. Had to get the silicon sealer off of the component. Turns out the sealer had bubbled and become warm. Close inspection indicated tha the resistor had a cracked/cold solder joint. Reflowed the resistor and cross my fingers.

Forgot to take pictures or get the exact resistor component number. It was a 200 series resistor R2XX. Located in line with the E9 ECU connector. The resistor was next to the 2nd vertically mounted transistor array that was about 1 1/4" wide by 3/16" thick.

Short story, the problem was with the cold/cracked resistor solder joint. Car would run about 20 minutes, then die. No tach when cranking, but the engine would run on brake cleaner.

Resoldering the bad resistor solder joint, priceless!