96 Ls400 Wont Start!

[yotoy82]

My 96 LS400 has a new issue. Today 5 minutes from home at the local walmart, I come back after shopping for 5 minutes. I try to start the car, and it wont start! It turns over just fine, battery has plenty of juice, it acts like its just about to start, but doesn't. I tried like 15 times. 2 or 3 times it kinda started, it was like ALMOST running but sputtered out, so I would say a few times it did start for a second then die, but not exactly, it wasn't fully started!

I had it towed to the local toyota dealer and waiting for the morning but want to know what you guys think it would be so I don't get tricked into something else etc.

Could it be the fuel pump? I changed the fuel filter 3 weeks back. Its been driving fine for the past month besides city mileage issues.

[yotoy82]

Still no replies? The dealer said they went to check it today and it started right up without any problems! That makes me more worried now that there is a problem with the car that will probably show up again later. Its there anything it might have been that I can prophylacticly change that might have been the problem??? I dont want to get stuck again somewhere

[curiousB]

Still no replies? The dealer said they went to check it today and it started right up without any problems! That makes me more worried now that there is a problem with the car that will probably show up again later. Its there anything it might have been that I can prophylacticly change that might have been the problem??? I dont want to get stuck again somewhere

Maybe coolant temperature sensor. If it is faulty your ECU could think the engine is cold when in fact it is warm. The ECU then would send too rich a fuel mixture possibly flooding the engine so it won;t start as you experienced. This could also explain your poor gas mileage you've been complaining about. Its a simple thing for the dealer to check and the part isn't that expensive.

[yotoy82]

Still no replies? The dealer said they went to check it today and it started right up without any problems! That makes me more worried now that there is a problem with the car that will probably show up again later. Its there anything it might have been that I can prophylacticly change that might have been the problem??? I dont want to get stuck again somewhere

Maybe coolant temperature sensor. If it is faulty your ECU could think the engine is cold when in fact it is warm. The ECU then would send too rich a fuel mixture possibly flooding the engine so it won;t start as you experienced. This could also explain your poor gas mileage you've been complaining about. Its a simple thing for the dealer to check and the part isn't that expensive.

I changed the coolant temperature sensor a month ago, the old one was completely broken, put a new genuine oem one in and the car was driving fine after that.

I did some research online and the dealer said it could be the Idle Air control valve, and people online have had the same problem. Do you just clean it or do you replace it, I dont know anything about the IAC, it sounds like something worth checking?

[curiousB]

It is a pretty good maintenance item to clean this up. If you are able you can clean the throttle plate and the IACV with the proper solvent.

I don't think the IACV would stop the car from starting though. To find out try starting with foot slightly pressing the gas pedal. If it won't start then either you have something else going on. Maybe intermittent fuel pump..

[yotoy82]

It is a pretty good maintenance item to clean this up. If you are able you can clean the throttle plate and the IACV with the proper solvent.

I don't think the IACV would stop the car from starting though. To find out try starting with foot slightly pressing the gas pedal. If it won't start then either you have something else going on. Maybe intermittent fuel pump..

Yeah, guess it won't hurt to have it done. Its working fine now completely. If its an intermittent fuel pump, there really is no way to diagnose that is there.

[GKLCPA]

My 96 LS400 has a new issue. Today 5 minutes from home at the local walmart, I come back after shopping for 5 minutes. I try to start the car, and it wont start! It turns over just fine, battery has plenty of juice, it acts like its just about to start, but doesn't. I tried like 15 times. 2 or 3 times it kinda started, it was like ALMOST running but sputtered out, so I would say a few times it did start for a second then die, but not exactly, it wasn't fully started!

I had it towed to the local toyota dealer and waiting for the morning but want to know what you guys think it would be so I don't get tricked into something else etc.

Could it be the fuel pump? I changed the fuel filter 3 weeks back. Its been driving fine for the past month besides city mileage issues.

I'm having this exact same problem which I posted in a string a few days ago. I suspect it's either the fuel pump or the sending unit. I'm getting the exact same symptoms. Plenty of juice, but just won't fire. Mines is a 1996 also with 200K on it.

It will do it again. This has happened to me at least once a month over the last 3-4 months. I wound up getting stuck 100 miles away from home with the problem. I had to stay in a hotel overnight because I couldn't get a tow and arranged a tow for the next morning. While waiting on the tow, I tried it and it started right up. This is too intermittent for the mechanics to figure out because they can't reproduce it and I've just resolved myself to replacing the fuel pump and the sending unit to see if that fixes the problem.

[GKLCPA]

Still no replies? The dealer said they went to check it today and it started right up without any problems! That makes me more worried now that there is a problem with the car that will probably show up again later. Its there anything it might have been that I can prophylacticly change that might have been the problem??? I dont want to get stuck again somewhere

Maybe coolant temperature sensor. If it is faulty your ECU could think the engine is cold when in fact it is warm. The ECU then would send too rich a fuel mixture possibly flooding the engine so it won;t start as you experienced. This could also explain your poor gas mileage you've been complaining about. Its a simple thing for the dealer to check and the part isn't that expensive.

I'm having the same issue and I've been getting poor gas mileage too and it seems that started happening at the same time I stated having the intermittent starting problem. I had a problem that my fuel was running too lean which generated a code on faulty front 02 sensors, which I replaced. I bet that may be the problem and that sensor is way cheaper than the fuel pump.

I had the car shudder one time during this period with the intermittent starting problem as well--as if something was wrong with the fuel. Would a faulty sensor cause that?

[yotoy82]

I really don't know myself. Fuel pump?? Its hard to say, I've googled a lot and failure of the LS400 fuel pump seems to be incredibly rare. Mine didn't have any codes in it

[GKLCPA]

I really don't know myself. Fuel pump?? Its hard to say, I've googled a lot and failure of the LS400 fuel pump seems to be incredibly rare. Mine didn't have any codes in it

I've opted to replace this temperature sensor to see if that fixes the problem before I spring for the pump. The pump and the sending unit look like the run about $ 350.00 + labor to put in. I suppose I could go ahead and do it, but I'd hate to spend that money and it not be the problem.

Let me know what you wind up doing to resolve.

[curiousB]

Thats an expensive way to fix your car. Try and replace. I doubt temp sensor would mean you can't start car. It might explain why its harder to start and has poor gas mileage but it should still start even with the sensor unplugged.

If you don't start at all its either fuel or spark.

You can spray starter spray (ether) into air intake while cranking to see if the engine "catches". If it does it points to fuel starvation. If not then need to check ignition.

[GKLCPA]

Thats an expensive way to fix your car. Try and replace. I doubt temp sensor would mean you can't start car. It might explain why its harder to start and has poor gas mileage but it should still start even with the sensor unplugged.

If you don't start at all its either fuel or spark.

You can spray starter spray (ether) into air intake while cranking to see if the engine "catches". If it does it points to fuel starvation. If not then need to check ignition.

yes, another poster suggested the starting fluid also to test and I picked up a can. I've already addressed the plugs, wires and rotors which needed to be replaced anyway and I figure the temperature sensor replacement is rather inexpensive, so I'm going to go ahead and do that. Before I attempt to replace that pump and sensor, I'm definitely going to test.

Question: Could an intermittent problem like this revolve around the starter?

[1990LS400]

Question: Could an intermittent problem like this revolve around the starter?

If your starter is spinning the engine fast enough to start it, then the starter is not the problem.

Randomly replacing parts is an expensive way to (try to) solve a problem ... it's almost always cheaper to take a car to a professional mechanic.

[GKLCPA]

Question: Could an intermittent problem like this revolve around the starter?

If your starter is spinning the engine fast enough to start it, then the starter is not the problem.

Randomly replacing parts is an expensive way to (try to) solve a problem ... it's almost always cheaper to take a car to a professional mechanic.

Thanks and I agree that randomly replacing parts is not something one wants to do. I've tried three different mechanics, including Lexus, but they've come up with nothing. (Lexus tried to convince me to replace the starter). They need to car in the non-starting condition to determine the situation and can't seem to determine what the problem might be. So, I'm on my own at this point, which leaves me guessing at what to address. The only thing I can do is do the cheaper maintenance stuff that needs to be done anyway, like the temp sensor, and try to isolate the problem with the starter fluid test as a couple of people have suggested.

[SRK]

If the mechanics "came up with nothing" then they are not mechanics.

Replacing parts as some sort of maintenance that "needs doing" is just going to waste your money.

Diagnose the damn thing and fix that, and only that. That's been said many times already.

It's not the plug wires, or the plugs, or the temp sensor, or the distributor caps. It's something that affects ALL cylinders and prevents fuel or spark completely. Get it?

[landar]

If the mechanics "came up with nothing" then they are not mechanics.

Replacing parts as some sort of maintenance that "needs doing" is just going to waste your money.

Diagnose the damn thing and fix that, and only that. That's been said many times already.

It's not the plug wires, or the plugs, or the temp sensor, or the distributor caps. It's something that affects ALL cylinders and prevents fuel or spark completely. Get it?

Have to agree with SRK. The bottom line is that you need three ingredients to get the engine running...fuel, spark and timing. The timing really is not in question since it does run most times.

You have a "tough dog" here. Intermittent behavior is what is throwing these mechanics for a loop. So, it is up to you to do the sleuthing and get to the root cause.

If it runs then it runs. Be happy. Life is too short to worry. However, be prepared to do some diagnosis when it acts up again. Number one, carry a can of starter fluid with you and be prepared to use it. Starter fluid is highly flammable, so don't go crazy spraying it into the intake snout but use enough to give the engine a chance to fire. Probably 2-3 seconds of mist will do. Repeat one time.

If that produces no starting results, spring into action and check the spark. You can buy a little strobe light to hook to the high tension wire of each coil or each spark plug wire.

Once you have it narrowed down, then you go on the witch hunt. This tough dog will take some patience and a resolute, logical mind. I love these mysteries.

And, worst case, if you cant get it fixed, you sell to me...cheap! I fix. :whistles:

[GKLCPA]

If the mechanics "came up with nothing" then they are not mechanics.

Replacing parts as some sort of maintenance that "needs doing" is just going to waste your money.

Diagnose the damn thing and fix that, and only that. That's been said many times already.

It's not the plug wires, or the plugs, or the temp sensor, or the distributor caps. It's something that affects ALL cylinders and prevents fuel or spark completely. Get it?

I'm not one to throw away money and perhaps your finances can't handle $ 30 on a temp control sensor, but mine can. Same applies to the plugs and wires. The car has 200K miles on it and these needed to be replaced anyway and my finances can absorb that and I'm ok with that.

I don't need to defend what I'm doing when I'm here seeking information on how to solve a problem which apparently at least one other person has. Hell, even here, there's been a difference of opinion over what the issue is and the bottom line is I have to do what I have to do to resolve the problem. I think we all know that it's either the spark or the fuel. If you've some specifics to offer in that regard, I've no problem hearing it, but your critique on my spending $ 30 is not something I can use. Get it?

[GKLCPA]

If the mechanics "came up with nothing" then they are not mechanics.

Replacing parts as some sort of maintenance that "needs doing" is just going to waste your money.

Diagnose the damn thing and fix that, and only that. That's been said many times already.

It's not the plug wires, or the plugs, or the temp sensor, or the distributor caps. It's something that affects ALL cylinders and prevents fuel or spark completely. Get it?

Have to agree with SRK. The bottom line is that you need three ingredients to get the engine running...fuel, spark and timing. The timing really is not in question since it does run most times.

You have a "tough dog" here. Intermittent behavior is what is throwing these mechanics for a loop. So, it is up to you to do the sleuthing and get to the root cause.

If it runs then it runs. Be happy. Life is too short to worry. However, be prepared to do some diagnosis when it acts up again. Number one, carry a can of starter fluid with you and be prepared to use it. Starter fluid is highly flammable, so don't go crazy spraying it into the intake snout but use enough to give the engine a chance to fire. Probably 2-3 seconds of mist will do. Repeat one time.

If that produces no starting results, spring into action and check the spark. You can buy a little strobe light to hook to the high tension wire of each coil or each spark plug wire.

Once you have it narrowed down, then you go on the witch hunt. This tough dog will take some patience and a resolute, logical mind. I love these mysteries.

And, worst case, if you cant get it fixed, you sell to me...cheap! I fix. :whistles:

Landar, I picked up the starter fluid the day you suggested it on the other thread and thanks for the suggestion above.

If the car fires, would you conclude it's the pump or the sending unit? Also, could one faulty coil result in the car not starting? I've replaced the spark plug wires, so that variable is eliminated.

[GKLCPA]

If the mechanics "came up with nothing" then they are not mechanics.

Replacing parts as some sort of maintenance that "needs doing" is just going to waste your money.

Diagnose the damn thing and fix that, and only that. That's been said many times already.

It's not the plug wires, or the plugs, or the temp sensor, or the distributor caps. It's something that affects ALL cylinders and prevents fuel or spark completely. Get it?

Have to agree with SRK. The bottom line is that you need three ingredients to get the engine running...fuel, spark and timing. The timing really is not in question since it does run most times.

You have a "tough dog" here. Intermittent behavior is what is throwing these mechanics for a loop. So, it is up to you to do the sleuthing and get to the root cause.

If it runs then it runs. Be happy. Life is too short to worry. However, be prepared to do some diagnosis when it acts up again. Number one, carry a can of starter fluid with you and be prepared to use it. Starter fluid is highly flammable, so don't go crazy spraying it into the intake snout but use enough to give the engine a chance to fire. Probably 2-3 seconds of mist will do. Repeat one time.

If that produces no starting results, spring into action and check the spark. You can buy a little strobe light to hook to the high tension wire of each coil or each spark plug wire.

Once you have it narrowed down, then you go on the witch hunt. This tough dog will take some patience and a resolute, logical mind. I love these mysteries.

And, worst case, if you cant get it fixed, you sell to me...cheap! I fix. :whistles:

Another question here also. About the time this started happening, I got a code indicating that my fuel was running too lean and I replaced the front 02 sensors as a result. At or about the time I began having the intermittent starting problem, my fuel mileage started to decline slightly. I would routinely get 18-19 mpg and now I'm getting about 15-17. Not a big difference, but noticeable for me since I check it all of the time. The mpg did not return back to normal after I replaced the o2 sensors. About a month ago, I had a p0420 code pop up and was told by one mechanic that my driver's side cat was bad. That may be affecting my mpg.

I'm thinking this thing is somehow related to the fuel. Thoughts on the above?

[SRK]

Knock yourself out boy. Spend it if you've got it.

[GKLCPA]

Knock yourself out boy. Spend it if you've got it.

I find that it's a good thing to maintain a degree of insouciance about what people may post on the internet. There are several reasons for that, but the best thing about that stance is that it provides a good filtering mechanism, otherwise one can wind up "drowning in a puddle" over nothing. Life is too short to get caught up in anything that leads nowhere. So, if you don't mind, I'll engage with others and won't distract from this forum (or from a resolution of my problem), by getting into a back and forth with you over nothing.

[landar]

Another question here also. About the time this started happening, I got a code indicating that my fuel was running too lean and I replaced the front 02 sensors as a result. At or about the time I began having the intermittent starting problem, my fuel mileage started to decline slightly. I would routinely get 18-19 mpg and now I'm getting about 15-17. Not a big difference, but noticeable for me since I check it all of the time. The mpg did not return back to normal after I replaced the o2 sensors. About a month ago, I had a p0420 code pop up and was told by one mechanic that my driver's side cat was bad. That may be affecting my mpg.

I'm thinking this thing is somehow related to the fuel. Thoughts on the above?

I know this may sound counter-intuitive, but your best bet at getting at the root cause will be hoping that the engine dies completely and will not start at all. Those are the much easier problems to solve. Then you can get in and start checking each system for operation and get this problem narrowed down. I would get the car "instrumented" as best you can before it acts up again. Like put your spark measuring tools in place or have them in a really handy place so you can quickly deploy them. The worst thing is for the car to start operating again w/o having been afforded the opportunity to do a little testing.

I am not a big advocate of replacing parts while the engine is still acting up. The reason being is that you may introduce a new problem that was not there before. It is not out of the realm of possibility to get a so-so part that will cause more grief and compound the troubles. So, while I am with you on replacing parts for maintenance reasons, I would caution against much of that until the root cause is identified. I suppose if you replace parts one at a time when the engine is running well and it does not cause any problems, it is ok. On the other hand, you may have to perform some level of experimenting and replacing parts is justified after you have narrowed things down some and have reasonable doubts about its performance.

You might want to invest in some scan tools for your own use. There are some PC-based tools that can help you understand fuel ratios and flow, temperatures, sensor readings, etc. The poor mileage may or may not have anything to do with the current maladies. Intermittent starting problems are usually associated with poor connections or failing sensors. To address your earlier question, a single coil being bad would certainly cause problems but others report that the engine will at least run..very poorly but it does run. So, I doubt a single coil is the issue. A cat that is partially plugged would begin to affect mileage as the exhaust flow is impeded. Seems that cats tend to go after approx. 150-200k miles so if you are in that range, they may be needing replacement. They are big buck$ unfortunately.

[yotoy82]

Well I got an update on my car problem. If you don't remember, it wouldn't start, and the next morning started just fine. Now 2 weeks later or so, a problem has again emerged at the same time in the evening. While driving, it started to jerk/hesitate, then smoothed out again. Then when I pushed the accelerator, it wouldn't increase speed. I was driving 30 miles per hour, I pushed the gas pedal, but NO RESPONSE. Then like 5 seconds later all of a sudden that surge of power. Its like the fuel came to it late! Then there was a misfire/pop sound from the engine bay. I kept driving home and the same issue kept on, car drove fine, but the delay from pushing the accelerator until it sped up was about 3-5 seconds! What could this be? A slowly failing fuel pump or something related to it? I mean when the fuel finally came to it or when it reacted, it took off smoothly and with a lot of power.

[yotoy82]

Welp, it sputtered all the way to my toyota dealer and finally died for good over there, they finally diagnosed it as a bad fuel pump. Online the original Lexus fuel pump is like $306. I saw an aftermarket Denso one for $118. Which one should I go for? I read that denso makes the original part anyway.

[GKLCPA]

Welp, it sputtered all the way to my toyota dealer and finally died for good over there, they finally diagnosed it as a bad fuel pump. Online the original Lexus fuel pump is like $306. I saw an aftermarket Denso one for $118. Which one should I go for? I read that denso makes the original part anyway.

Yoyo,

I can't advise you on the part, but I'd have them check the sending unit also. That price for the Denso seems pretty good though.