96 Ls400 Doesn'ts Start/ Starts Then Dies

[BobSmith007]

I have a 1996 LS400 that is giving me some troubles. Here is a rundown of whats going on.

About four months ago, sometimes it seemed like at night the headlights would sorta dim, but wasn't sure thought maybe my eyes were playing tricks on me.

Two weeks ago starting the car up, the dash lights/radio etc slowly fade out, and the the car dies. Wait about 20 minutes, car will start back up. Five minutes later dies. Checked the battery with a multimeter, it has 12.58ish when at rest, starting the car, the voltage of the battery is just steadily going down, until it doesn't have enough power to keep it going, and it dies.

Decide this means the alternator has gave up working. Take off alternator, take the parts houses, they put on the testing machine, both places that tested it, it comes back fine. So I decide, maybe the battery is the issue. Test the battery, its fine. Try another battery in car, it works fine until having drove the car a bit, and then it's not charging the battery anymore.

An alternator specialist said that it's likely the alternator is about completely dead, but will still pass the tests on the machines, would need to open it up and look at it to really come up with a firm answer. Decide to just pick up a rebuilt alternator.

So Yesterday I go to move the car up on the ramps to make it easier to do the alternator removal and replacement. Car fires right up, and I start to get it in position, and it dies. It acted like it would when the battery was too run down, so I let it sit for awhile and tried again, but the car will not stay running/start. Basically I turn the key, and it sounds like its going to crank, and then it doesn't. But when spraying starting fluid into the car, it will start and ruin until the starting fluid is used. So I feel like it is not getting any fuel. I listened for the fuel pump to come on, and did not hear it.

I checked the fuel pump relay and also checked out the fuses, and they looked ok.

Sorta out of ideas. The CEL is on, and has been, last dozen times it got checked either via parts house or dealership they all declared it was the oxygen sensors needing to be replaced, that it wasn't a DO RIGHT NOW issue, but just do it at some point.

Any ideas?

[mjfuture]

Check the plugs and the injectors with them wires.

Also the air filter.

If they are fine or you have them changed and cleaned recently then simply test the computer.

BTW are there any smoke or noted carbon smell coming out?

[BobSmith007]

I've not changed or cleaned the plugs/injectors nor the air filter.

How do I go about testing the computer?

I've not noticed any smell out of the ordinary.

[mjfuture]

when was the last time you cleaned the injectors and air filter?

This model plugs could last for ever but that depends on your driving.

You can test the computer yourself if you have the tools or at a shop with a tester, the computer will tell you what's wrong in the system.

Check this out

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

good thing there is no smell or smock cuz that may force you to change the computer.

[BobSmith007]

I have't cleaned the injectors, the air filter was done maybe 6 months back.

Yeah I don't have the tools to test it, and I'm quite a ways from anyone to do any testing.

It's starving for fuel as best I can tell, but I'm not sure if the fuel pump went out, or where along the fuel path I have an issue. I do know that spraying the starting fluid will keep it going until all the starting fluid is used up.

[mjfuture]

Its not common for the fuel pump to break down.

I think There are dirts in the path, but to be safe change the spark plugs and use STB to clean the injectors (do not remove the injectors unless you are changing them) That's what would I do

Also clean the air filter cuz the dust cuses the engine to use more power to get the air in which mean more fuel.

I had similar issue but once I replaced the plugs and air filter cuz it was to old to clean, everything turned better.

Hope I helped

I've braking issue with my ls400 so I parked it far at my grandfather place till the parts arrive, tomorrow i'll go to clean it and check the fuel electronic system for you.

[Glenn Schabel]

Sounds like you have two issues here, electrical / alternator and fuel.

First we need to keep fuel going to it before we can troubleshoot other things.

Before you do the fuel pump, change the fuel filter, especially if it is original. It is inexpensive as well!! That has happened to me. From there you can get into more technical things if needed.

Good luck!!

[BobSmith007]

I guess the phrase "when it rains it pours" is apt here.

I was thinking it was just the alternator that was needing replacing, then whatever happened with the fuel system. Hopefully it is the fuel filter. I have a spare, I may try that out in just a bit.

Thanks much for the ideas so far folks. Its helpful,

[landar]

You can measure the fuel pressure at the fuel rail to see if it is proper or not. However, the computer is trying to tell you something and researching the exact code could be very helpful. With a '96, you should have the OBDII system so get the code(s) read from the local auto store and let us know the Pxxxx code(s) you get before changing any parts. It could save you some money.

[SRK]

It's not the spark plugs, it's not the injectors, it's not the air filter. It will be something that affects all eight cylinders at once.

So as Landar suggests, check fuel pressure. If that's ok, then check for codes ( or do that first if they are present) and then check for system voltage. The ECM will shut off below a specific voltage. At the very least monitor voltage while the engine is running with a multi-meter. Place the battery on a charger if you suspect the battery - ensure it is fully charged.

More than likely it is something simple. And I would suspect the battery, or it's cables, and/or the alternator. Given the effort needed to re and re the alternator I would not re-install it without replacing the brushes, which cost about $20.00.

[BobSmith007]

Now I'm not the most mechanically enclined person, I'm more a computers and chemicals guy. So Checking the fuel pressure at the fuel rail would entail what? I didnt see a schrader valve, but with a little info suspect I can do that.

ODBii reading sadly will have to wait, I can't get it to a parts house, and I do not own a reader or know anyone that does. Or at least off hand I dont.

But I shall figure out a way to get the Code.

[BobSmith007]

I still haven't been able to get ahold of an odbii reader, and it rained a number of days after my first posts. Without the required stuff to legitly check the fuel pressure. My friend had an idea.

So Here is where I am. Disconnected the flare nut end of the fuel filter.

Turned key to on position, nothing happened.

Turned Key to cranking/starting position fuel squirted out. It appeared to be quite a bit. So the key was turned off.

My question is that normal? Other cars I've drove when turning the key to on, the fuel pump does something, this one is only doing something when attempting to start the car, and its putting out a Healthy dose of gas.

[SRK]

Some cars run the pump for second or two as the key is first turned to "run", others during cranking. Usually an RPM signal is needed to keep the pump running once the engine has started.

You seem to have fuel pressure. So you're back to battery voltage. Check the voltage during cranking - should be no less than 10v.

[BobSmith007]

I know the last time I watched the voltage while attempted to crank the car, it dipped down to I want to say about 9.26V.

But Tomorrow I will check again, I've ordered an ODBii reader, but am unsure when it will arrive.

Someone suggested that the Positive battery cable on these cars sometimes go bad due to battery corrosion, Could that maybe be something? I've checked various fuses and relays to see what I could see, but all looked like they should.

[SRK]

A reading below 10 is no good. The battery is probably undercharged or has failed. For sure the terminals should be removed, cleaned and re-tightened.

[landar]

It is really hard to diagnose with small clues here and there and without being there to makes some simple checks. However, bear in mind that this is probably something fairly simple...most issues are. You mention checking the voltage at the battery and it being 9.26v. That is fine IF that is a reading WHILE cranking. The starter draws a lot of current when cranking (>100amps) and the battery will drop down in the 6-8 volt range under normal conditions while delivering high current. However, it should spring right back to the +12v range once you stop cranking.

Now, you should be checking the voltage right at the posts of the battery AND then at the connectors to the battery. There should be NO difference between the two readings otherwise you have a cable connection problem. So, with the car not running, turn on the headlights. Check the voltage directly at the battery terminals (posts) then just move over to the battery clamps. Also, the voltage with the lights on should slowly creep down to +12v and perhaps a bit under(11.75) after 10 minutes or so. If it starts taking a dive with the headlights on and goes under 11.5v, the battery is bad or is not charging. Again, check directly on the terminals and then on the cable connectors and let us know if there is any difference.

[BobSmith007]

It is really hard to diagnose with small clues here and there and without being there to makes some simple checks. However, bear in mind that this is probably something fairly simple...most issues are. You mention checking the voltage at the battery and it being 9.26v. That is fine IF that is a reading WHILE cranking. The starter draws a lot of current when cranking (>100amps) and the battery will drop down in the 6-8 volt range under normal conditions while delivering high current. However, it should spring right back to the +12v range once you stop cranking.

Now, you should be checking the voltage right at the posts of the battery AND then at the connectors to the battery. There should be NO difference between the two readings otherwise you have a cable connection problem. So, with the car not running, turn on the headlights. Check the voltage directly at the battery terminals (posts) then just move over to the battery clamps. Also, the voltage with the lights on should slowly creep down to +12v and perhaps a bit under(11.75) after 10 minutes or so. If it starts taking a dive with the headlights on and goes under 11.5v, the battery is bad or is not charging. Again, check directly on the terminals and then on the cable connectors and let us know if there is any difference.

Before I say anything else, I just wanna agree with you about how hard it is to diagnose things from a distance, I sometimes/often happen to be the guy that is called for computer tech support, and well I know how that goes, so again Massive thanks for taking the time to try to help me out.

On to what I've learned today.

I misspoke, the battery only drops down to about 10.4ish when attempting to crank, then it goes back up to 12.45ish.

I checked at the posts and on the connectors, and there was no difference between the two. I did it via the headlight check, the voltage did go down and was around 11.8 after 11 minutes.

Using a timing light, we confirmed that on both sides it is getting fire.

Also observed that the fuel line gets firm with fuel when turning the key.

I took a video of what happens, complete with sound, that I'm currently uploading to youtube.

Will post again with the video url and whatnot.

Thanks again.

[SRK]

Sounds like loss of fuel pressure. You have good cranking speed, good compression on all cylinders, ignition. You need to check fuel pressure at the rail.

[landar]

From the video, I think the battery is very strong and everything appears to be fine...until the engine actually fires and begins to run then abruptly stops. Almost seems to me like an errant sensor is telling the computer to shut the engine down. Maybe the computer is cutting fuel via the injectors or fuel pump(and you are bypassing the fuel cutoff with starter fluid)? Based on what I see, I would now give the battery/alternator a clean bill of health and concentrate on the CEL codes. Agree with SRK...does seem fuel related.

[BobSmith007]

An ODBii reader is on the way to me, but I'm unsure of when It shall get here.

I know the problem it was having, the original one, was if the battery wasn't being charged, and it running just on the battery until it became too weak to run, and would go dead. Waiting 30ish minutes the battery would then have enough power to again start the car, and move it some.

Either the alternator was working for a bit then giving up, or something else was telling it to turn off or who knows what.

I know we checked all the fuses and they all tested fine, even the cartridge fuses beside the main fuse block.

[landar]

Based upon your video, I had another thought that perhaps the fuel pump is being de-energized when the key goes to the 'run' position. I have seen that kind of behavior on other cars when the ignition switch is going bad. I would monitor the fuel pump relay (or the voltage to the fuel pump) to see if the relay cuts out as soon as you let off the key to the 'run' position. I do not think the spark is going away based upon your previous use of starter fluid to keep it running.

[rugbyhead]

If you put a freshly charged battery in and the car runs you should use a voltmeter to then check the voltage at the battery. It should read approx 14.5V. If you are only getting battery voltage(below 12.6V) then use the voltmeter to check the voltage at the alternator. Connect between the alternator housing (-)and the main bolt on connection(+).If you are getting 14.5V there then you have a bad connection in the charging circuit between the alternator and the battery. You should also check the voltage at the alternator with the engine off. It should read the same as the battery. If you have no voltage then the problem is caused by the main + cable being open circuit. This could be the fault of the alternator fuse.

[BobSmith007]

Well more stuff to add to this topic.

Got the ODBII reader finally. Amazon sorta went screwball with shipping it.

So I plugged it up as instructed, and followed the letter of the instructions...

Told me NO CODES. Even though the Check light is still on.

[landar]

Drive your car to the nearest Autozone/Advance/Pepboys/Sears/whatever..and have them scan it for free.

What brand/model of scanner did you buy?

[BobSmith007]

Car not so much into the whole driving thing at the moment. Got the guy from a local parts house to bring out his scanner and hook it up, same thing says no codes, but the CEL is on. Pretty much the idea now is the ECU has took a dump.