96 Ls400 Wont Start!

[SRK]

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.

Denso makes excellent stuff, so the cheaper pump should be fine. The problem is whether the dealer will install customer supplied parts, if that's your intention. If you are installing it yourself, they'll charge you diagnostic time ( gee I love that term....) whereas if they install their own pump they may not. You'll have to ask.

Sounds like it's about to be fixed either way.

[GKLCPA]

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.

Landar, you're right. This intermittent thing is worse than the car just not starting. I wish I was in Yoyo's situation. I hear you too on introducing too many variables and producing other problems. Although I'm a CPA by profession, I'm fairly knowledgeable when it comes to computers and diagnosing issues and I can recount the number of times where something was made worst by introducing a change that created an additional problem to solve while throwing you off the hunt on the original one. So, I'll go easy and carefully in that regard. I may have addressed the mileage problem today as when they were putting in the temperature sensor, they found a couple of bad vacuum tubes which got replaced. We'll see what happens.

Thanks for your response and sage advice.

[yotoy82]

They are quoting pretty expensive labor, he said 3 hours, its kind of hard to argue with a dealer on prices, but one can only try. I know it must be pretty easy to install myself , but they already have it taken apart to diagnose it. $118 for the pump. If I decide to do it myself, it'll be around $70 to tow it back to my house, then probably another $70 for their diagnostic charge, and then the trouble of doing it myself, I guess if they agree to install my parts, its worth the extra money to have them do it. Theres no way I was going to pay their quote of $380 for a lexus fuel pump which is availble online for $280.

I guess I'll call them and see if they'll install my denso pump for me. $115 at parts geek with 7 dollars shipping, cant beat it.

[curiousB]

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?

O2 sensors have no impact at starting. The ECU ignores them until the engine and the sensors are fully warmed up. As a result a starting problem wouldn't be due to O2 sensors.

Bad fuel can be a problem. Since you had the problem a while i assumed you'd been through a few tanks. If not fill up with fresh fuel and try. Maybe add some HEET (or equivalent gas additive) to fuel in case some water got into the tank...

[GKLCPA]

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?

O2 sensors have no impact at starting. The ECU ignores them until the engine and the sensors are fully warmed up. As a result a starting problem wouldn't be due to O2 sensors.

Bad fuel can be a problem. Since you had the problem a while i assumed you'd been through a few tanks. If not fill up with fresh fuel and try. Maybe add some HEET (or equivalent gas additive) to fuel in case some water got into the tank...

Thanks Curious. I've done the thing with the fuel additive twice thinking water or something was the issue and switched where I was buying fuel from as well. I got a code on the front 02's with an indication that the fuel mixture was too lean, but that may have been related to a vacuum leak which got addressed yesterday when I replaced the temperature control sensor. According to what I reading on the web, the vacuum leak could make the fuel mixture to lean to fire. That leak might also explain the decline in gas mileage I was getting also. They gave me one of the hoses they took out and it was in bad shape. Thoughts?

[Micah.Berry]

While not a mechanic, my thought is that a bad vacuum hose (or a couple) might cause starting to be poor nearly all the time with too lean a mixture. I hope that the hose replacement resolves the starting issue, and brings the mileage back! May be if left alone the problem would become worse as the vacuum loss increased with hose deterioration.

Micah

[curiousB]

A vacuum leak will have symptoms of erratic idle because the leak is fighting against the action of the IACV. Worse still it is introducing air that bypasses the MAF so the ECU doesn't factor that air into the air fuel map lookup.

So air leak means erratic idle and possibly more difficult starting. Not sure it would throw gas mileage off that much though. Poor gas mileage is usually due to rich fuel caused by cold engine (stuck open thermostat) or perceived cold engine (caused by faulty engine temp sensor (the ECU temp sensor not the dash indicator one)), low tires inflation, sticking brake pads, dirty air filter,....

[yotoy82]

Welp, got my new fuel pump installed. The denso one, which was made in Japan, got it from autopartswarehouse, found a coupon at retailmenot.com , got it in one day even with regular shipping, like $120 total, works fine!

[SRK]

Welp, got my new fuel pump installed. The denso one, which was made in Japan, got it from autopartswarehouse, found a coupon at retailmenot.com , got it in one day even with regular shipping, like $120 total, works fine!

I'm glad you fixed it, and at such a good price!

[GKLCPA]

An update. The damn thing wouldn't start again last week. I let it set for an hour and it started up just fine. It was too dark to mess around trying to get the starter fluid in good. Fortunately, I was at the office and I just walked around the corner to get some dinner. When I came back, I was praying the thing wouldn't start, but it started right up. The next day, I picked up some Seafoam and dumped that into the tank and a few hours later, I got a P 171 code (fuel too lean again) and I suspect that I still have a vacuum leak, so I'm going to take it in next week to address that. The idle seems to be running high now. I took it to my mechanic and he tells me that there's also a pending "fuel too rich code" that cancels out the fuel too lean code. He clears the codes and tells me to wait and see if they come back on. I can appreciate the guy trying to save me money, but the fuel too lean thing has been a on-going issue and I felt he was just too backed up to deal with the issue and test for the vacuum leak. So, I'm going to take it to Toyota on Monday and have them check and replace the hoses as necessary. I was told by by Lexus and Toyota that the vacuum leak might be affecting other sensors in the car and might result in hard starting. So I'm going to address it and see what happens.

I resolved myself to just dealing with stuff as it comes up and continue driving the car with the hope that it dies or produces a discernible condition that can be addressed.

[yotoy82]

Welp, got my new fuel pump installed. The denso one, which was made in Japan, got it from autopartswarehouse, found a coupon at retailmenot.com , got it in one day even with regular shipping, like $120 total, works fine!

I'm glad you fixed it, and at such a good price!

I've been having a few problems besides the car not starting and so far, the new fuel pump has changed one major problem I had before.

The car would take FOREVER to warm up, and no one would believe me, but even when the car got warm, if I turned it off for 30 min it went back to full cold.

After changing the thermostat, the car gets warmer faster now, and it stays warmer. How could have putting a new fuel pump fixed this problem? I would have never guessed this as the issue.

[JNeil77]

I had a '95 Oldsmobile Cutlass Supreme that I replaced the gas tank on and immediately afterwards would not start for 20 - 30 minutes (made running errands a little tricky ;)). Anyways the problem was the Crankshaft Position Sensor. All newer cars are controlled with comp and the sensor being out totally screwed up the ignition process and threw it completely off. I replaced one of the 2 sensors, damn thing crumbled in my hand, and it seemed to work just fine. Now since I just got my LS400 and haven't really looked around too much I can't say if there are 1 or 2 Crankshaft sensors but that is where I would start.

[GKLCPA]

An update on my car problems with the intermittent starting issue. I had planned to take the car in to address potential vacuum leaks. I was sitting in the car on the phone last week with the car idling, when the idle started acting strangely (sputtering) and then car went crazy with codes and the track light flashing on and off. By the time I got home, it wouldn't start after shutting it off. (This intermittent starting problem always occurs at night and never during the day). I took it in to Toyota figuring they'd be able to analyze. The car wouldn't start for them at one point, but they weren't able to analyze. (This particular dealer is frustrating as they charge an arm and a leg and want to suggest everything under the sun to fix other than what you brought the car there for). So, I pulled the car from them and took it to another mechanic and we discussed the potential problem of a vacuum leak at the exhaust manifold. I've had a leaky exhaust manifold gasket that I've known about for awhile that needs to be replaced and we believe that this is the source of my problems with the lean fuel,the intermittent starting and the recent crazy idling. It's a fair amount of labor to deal with this.

I pick it up on Thursday and will see how it acts over the next couple of weeks. The intermittent starting issue was definitely occurring more frequently, so if something's going to happen, it will do so within the next two weeks.

[GKLCPA]

The saga continues. I took the car to Lexus again today. They tell me that there's really no exhaust leak related to the manifold gasket, just a hose attached to the exhaust near the manifold that needs to be replaced (they want $ 750). Toytta was wanting $ 1200 for the same thing and claiming they had to do the manifold gasket. I really think the service reps at this place are getting paid on commission as they really do try to come up with stuff just for the hell of it. So, in my case, my local Toyota is the stealer while Lexus is not trying to juice me.

The car is running like crap now and seems to be misfiring and it's not starting much more frequently. That's a major pain in the butt, BUT, I'm sorta glad to see it as that may mean a light at the end of the tunnel. For some reason, this always occurs at night. When it did it the other day, I did spray some starter fluid down the intake snout and it fired and ran for a few seconds before stalling out. Actually, I did this a few times to confirm. So, I'm pretty sure that it's some issue with the fuel system. Lexus is recommending a fuel induction cleaning (about $ 150). I think I'm going to go for that and see what happens. Maybe I'll get lucky.

[GKLCPA]

Well, the saga is still continuing with the intermittent start. The car ran much better after the fuel induction service recommended by Lexus, but has continued with the intermittent starting issues on at least 3 occasions since then. On one occasion, I was once again sitting in the car while idling and the thing started sputtering again, then stopped and I couldn't start it. I concluded that it had to be the fuel pump and took it back out to Lexus today to discuss with the service rep and the mechanic. After kicking it around, we decided to go for the fuel pump to see if this addresses the issue. I've been wanting to pull that trigger for awhile, but didn't want to wind up laying out the dollars and it not be the issue.

The car has been having the problem far more frequently here of late--like every other day, so one thing's for sure, I'll know within the next day or so whether the issue is gone.

[GKLCPA]

Also, I gotta say that my local Lexus dealer's service is excellent, no matter what happens here. First, they're not trying to gouge people and work with you to address the problem. I didn't find their prices much more than dealing with an independent. They installed the fuel pump for $ 400 which was about the same price I was getting from the independents in my area and I was given a loaner to boot. They definitely have a new customer as they've won my business.

[GKLCPA]

Well, looks like my problem is solved. The one thing I regret is not going with my first inclination and replacing the fuel pump at the outset. That delay actually wound up costing me more money trying to sort out what the problem was. In any event, I'm glad that this is over with and at 192K miles, I'm looking forward to putting another 100K+ on before I even think about getting another car. Believe me, in the midst of this headache, the thought did pass my mind of getting a replacement.