GliTCH

Edit: I apologize for the lengthy post, but this is a very strange problem that I have logged in complete detail which may be helpful for others who have the same issue. (Hours of Google and forum searches have shown it's a common problem for older SCs).

About a week and a half ago my oil pressure light started coming on intermittently. This has usually been happening for me right around the time I need to get an oil change and then the light stays off for about another 3,000 miles or so. Anyway, I'm not even sure this is worth mentioning because my real problem is this:

A week ago I decided to check the oil before a quick 100 mile trip. I stopped at a gas station, checked the oil and it was a little low so I added a half a quart. I don't know if this is worth mentioning but I didn't have a funnel at the time, and I was very tired, very wired and I did get about a capfull or so of excess oil around the oil filler cap which proceeded to work its way down onto the engine's surface. Some of it seeped into the black plastic strip that covers the 1UZ's plugs and wires on that cylinder bank. I know from previous experience that liquids don't really leave that area too fast because the area above a spark plug is kind of like a well that, after washing your engine bay (don't do it) or spilling a little oil, will tend to sit there.

Anyways, I'm digressing here. After adding a half a quart, I get in the car, try to start it, and it won't start. The engine cranks over great but will absolutely not fire. I get on the phone with a towing company for about 20 minutes, then after I get off I try the car again and it starts up. Thinking that maybe the problem had fixed itself I went on my way. I notice that the oil pressure light is off and has not come back since (even till now).

Most of the night went without incident. I made the trip up, parked my car in front of a friend's house for a couple of hours. We left and went to meet up with some other people in another part of town, about a 15 minute drive. After staying over there for an hour, it was time to come home. At 3AM, with everyone on location already passed out, I get in the car, try to start it and it won't start. Same as before. Cranks over but doesn't fire. I try to catch some Zzz's out back by the pool to prepare to deal with it in the morning. It's now 6AM. Sleeping out back by a pool on a summer night in Florida, on cheap outdoor furniture really isn't fun at all. I start feeling more compassion towards homeless people.

Tired, wired, and needing to be in at work in a little under 5 hours with a 1 hour ride back home, I get in aaand.. what the hell, the SC fires right up. I drive for 5 minutes and stop to fill up before getting on the highway. No problems starting up the car again to get home.

I researched the issue and while I did find several references to plugs, cables, and so on, the one problem that seemed to really fit the bill was the fuel pump ECU. After doing some basic things first like checking the air filter and fuses, unplugging and replugging cables and checking vaccum hoses and so on, and still seeing the same problem (starts fine while cold / cool, will not start while warm / hot) I decided to get a fuel pump ECU. I found one on eBay from a salvage company for 90 bucks, got it shipped for the crappiest shipping ever and it just came in about 4 hours ago.

So I switch it out, real easy job, took only 10 minutes.... start the car, it starts up. I smell gas while backing out of the driveway. Okay, no big deal, the engine is running rich because it needs to warm up. So far so good. I take it out for a drive, gentle at first and getting a little more aggressive as the car warms up. My goal is obviously to make sure that this really did fix the problem and to see whether or not, after driving it for a while, I can start it up again while the engine's hot. I notice that the engine is actually smoother now, or maybe I'm just imagining it? Shifts feel smoother and quicker than I remember, or maybe it was not driving my car for 5 days (and driving a loaner Saturn with no power anything, even steering, that made me have a newfound appreciation for my SC). Either way, I start having a good feeling about it, till, inevitably, I take it back home after a 15 minute drive. I have a Viper alarm on the SC that has been on there since I got it 3 years ago, and it has remote start. While the key is in the ignition, I can hit a button on the remote to keep the engine running even if I take the key out. So I do exactly that, just to let the car cool down while running instead of shutting it off abruptly. I get out of the car and sit in my garage looking at it as it's parked in the driveway, and I notice that there is faint white smoke coming out of the bottom of the car along the passenger side. I'm not sure if it was wafting backwards from the engine bay and out the side, or wafting forwards from the exhaust pipe and out the side.. but either way I kill the engine and let it sit for a few minutes. The smell isn't straight gas but it definitely has a hint of gasoline in it.

I try to start the car, and it's the same issue. Cranks but won't fire.

During the run with the new fuel pump ECU I had no idle issues, no jerking, no power loss, no ignition timing, or any other performance issues. There are no diagnostic lights indicating a problem. The oil pressure light doesn't come on. I am due for an oil change but since I don't feel safe getting under the car while it's on jackstands and I really don't want to chance being stuck at a Jiffy Lube for 6 hours, I wanted to know if there was something else I could check for from here before attempting the obvious. Given what I've experienced, do you think this is an electrical/electronic issue or a mechanical issue? Could something like a simple oil filter / fuel filter change fix the SC400 not starting up while the engine is hot?

GliTCH

Update: Got an oil flush, filter change, and had them fill it with Pennzoil 5W30 synthetic. I also got a new cheap paper air filter (as a backup until I get he filter cleaner to clean my dirty reusable K&N). But after doing just that basic maintenance the car appears to start fine when warm now. As soon as I got it back after the oil change I took it out for another spin, warmed up the engine, then raced it for a bit, then brought her back home. Killed the engine, waited a minute, started it and it started up. I could hardly ****ing believe it. In fact, I didn't, so I killed the engine, waited another minute, then started it up again, and I let the remote start shut it off after 15 minutes. Waited 5 minutes, started it, and it started. At that point, I started feeling a lot better about the car, even though I still, till this second, am extremely skeptical as to how a simple oil and filter change could fix what definitely appeared to be a complex problem that involved engine management and signaling. Just before starting this post, I started the car up for a third time, let it run through the 15 minute timer, then waited a minute and sure enough, as of a few minutes ago it started up fine.

I'm extremely confused, still somewhat skeptical, just a bit paranoid and still wondering if there's something else I should be checking for given the history of the issue and the steps I've taken.

sc-driver

iTrader: (7)

Amazing how simple maintenance will go such a long way.

I'm starting to wonder if the problem was that the old air filter was so dirty it wasn't letting air through.
If it happens again, take out the filter and try it. Let us know how things turn out for you.

GliTCH

As it turns out, that wasn't the problem. I took my car in to Wilde Lexus of Sarasota, they called me the other day citing a starter issue. Really? I find that a little hard to believe, it doesn't sound like the starter is having any issues at all when I crank the engine about 50 times in the 5 hours it takes for me to start it up. Any last ideas? If I don't get anything definitive I'm going to probably end up parting the car out.

IS_250

iTrader: (2)

I doubt its a starter issue. If it turns over but wont fire its probably either ignition or fuel.

Are you still having starting problems? I just had my starter replaced last week and it cost me a grip of cash. I suggested trying all options before replacing it.

StiCk3

iTrader: (5)

I don't think it's a starter issue if it cranks over just fine, but doesn't fire. Best thing i can suggest is checking the spark plugs and wires. If you have the equipment or know someone who does do a fuel pressure test to see if there is enough fuel pressure at start up (specs. call for 38-44 psi). If it is low it might be a bad pump all together or a fuel pressure regulator. Go ahead and replace the fuel filter just to be on the safe side though. Don't take it to that Dealership though, unless they don't know the whole story you mentioned here then I would find some other opinions.

schwarz

iTrader: (3)

Get another fuel pump ECU from R&J or aliga and try replacing it again...the 'new' one could be on it's way out as well (speaking from experience)

LEX_MAN

iTrader: (2)

Did you try to do the 12v fuel ecu(Fp and the +b) jumper?

cbrasian

easy way to check though sounds like possible ignigter problem (but without diagnosing it and taking the time to fully read your thread) here is a few tips for you... if you think its fuel try this spray some carb cleaner in the intake and have some one try to start the car if it starts your problem is fuel side simple and easy way to check

visi0n

i have the same problem with my SC400. I cannot figure it out, and i recieve no check engine light.

GliTCH

I figured this out, by the way. After buying my new IS 250 I kept my SC and had some friends look at it. Believe it or not the issue is with the alternator, it's slowly failing and it won't keep the battery fully charged. The battery will have enough juice to start the SC before a long drive, after that drive there aren't enough CAs to turn the engine over quick enough. You can test this by jumping the battery with another car that's large enough. What happens when you let the car sit to "cool down" is the battery gains just enough of a charge to crank the engine and fire the cylinders.

The deterioration of the alternator is still TBD. I believe it may be because the power steering pump is slowly starting to leak PS fluid on it again, which is a common problem with older SCs.

sccd

iTrader: (1)

I had the same problem with not starting when warm. 92 sc400 changed the ECU next to the back seat, drivers side, with a used one from the junk yard. Problem fixed.