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1993 Sc400 Will Crank But Not Start


raytbo
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This car was garage kept for 17 years,only 119,000 miles, finally made it my airport car. Now it sits outside and is only used about every other month. The battery died within about 3 months. Recharged it and it would only get to 85% capacity after 8 hrs @2amp and 3 hours @8amp charge. Car still fired up as normal. Filled tank with 10% blend ethanol, Georgia law now, and drove for about 50 miles. Ran perfectly fine, as always. Only 3 weeks later, went to start it, yes, battery needed a jump, but that little push allowed the motor to crank effortlessly, and unfortunately, continoulsy with no fire or even a hint of fire. Let starter cool for 15 minutes and retried, same result. Could the ethanol blend be causing the problem? Should I disconnect the battery and let it sit and then reconnect. Since it won't fire, should I check the engine codes first? Or could it be something else caused by sitting outside and not being run but once every other month. I have checked the numerous other posts on matters like this, but haven't had another chance to troubleshoot the problem. I also bought and installed one of the solar panel 1.5 volt battery maintainer devices that plug into the cig lighter( did this 3 months ago), could this cause any problems?

Thanks for any advice.

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  • 4 weeks later...

  • 4 weeks later...

Going to try working on it tomorrow, all indications point to bad ECU. I have no CEL when I turn on the ignition. Am going to ck for fuel flow and ignition. It's too noisy(were it is parked) to tell if the fuel pump comes on when I turn the ignition on.

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This is the latest troubleshooting update. I replaced the battery which had a bad cell, turned on the ignition key to accessory and then to the start posit, without cranking the engine. did not have the Check engine light illuminate and did not hear the fuel pump running. I did hear a solenoid click but that was it. The engine did not start.

I remembered that after I filled the tank up and started to drive away(3 months ago), there was a what appeared to be a loud,but brief clanking noise emmanating from the rear of the car. I thought I had run over something but didn't notice anything in the rear mirror as I drove away. Would a fuel pump failure give that type of indication? Also, would the engine continue to run if the fuel pump failed while the engine was running?

Thanks for any advice on this.

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  • 1 month later...

check all fuses related to fuel, spark, ignition. Test for spark! pull a plug, put leave the plug wire on it, ground it to metal and crank it over and look for spark. If you hear the relay clicking when you turn the key to prime the pump then resort to testing the pump.

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This car was garage kept for 17 years,only 119,000 miles, finally made it my airport car. Now it sits outside and is only used about every other month. The battery died within about 3 months. Recharged it and it would only get to 85% capacity after 8 hrs @2amp and 3 hours @8amp charge. Car still fired up as normal. Filled tank with 10% blend ethanol, Georgia law now, and drove for about 50 miles. Ran perfectly fine, as always. Only 3 weeks later, went to start it, yes, battery needed a jump, but that little push allowed the motor to crank effortlessly, and unfortunately, continoulsy with no fire or even a hint of fire. Let starter cool for 15 minutes and retried, same result. Could the ethanol blend be causing the problem? Should I disconnect the battery and let it sit and then reconnect. Since it won't fire, should I check the engine codes first? Or could it be something else caused by sitting outside and not being run but once every other month. I have checked the numerous other posts on matters like this, but haven't had another chance to troubleshoot the problem. I also bought and installed one of the solar panel 1.5 volt battery maintainer devices that plug into the cig lighter( did this 3 months ago), could this cause any problems?

Thanks for any advice.

Back feeding into your lighter is never a good thing. Besides, if the lighter circuit only has power when the ignition is on, how can it get to your battery? I got one of those solar battery chargers that plug in to a lighter socket that someone left in a trade-in. I laid it out in the sun and measured 24 VOLTS coming out of that thing! Way too much! No check engine light with the ignition on is even worse. It's not likely your ECU crapped out just sitting there. More likely you blew a fuse wiring something backwards or (depending on your location) rats munched on your wiring harness under the hood. Find out why the check engine light doesn't come on with the ignition and you will find your problem.

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  • 3 weeks later...

Finally got the engine to start last month. This is what I came up with.

Just so you know, I am not an expert or even a mechanic for Lexus. My experience comes from being pretty good at working on my 65 Mustang, from engine to brakes(much simpler on those cars). I spent quite a few hours on the forums to find any leads to this problem. The one common theme seemed to be the Lack of a Check Engine Light,CEL,when the key was turned to the ON position, the position prior to engaging the starter. This seems to be a very common theme on the 91-96 Lexus SC400 and LS400.

Checked for fuel, there was plenty being pumped into the fuel filter.

Checked the fuses, all good. EFI relay, checked good when pulled then reinstalled. Have the key in the on posit prior to reninstalling the efi relay(so you can listen for the fuel lines being charged) I could hear the fuel charging thru the lines.

After looking at the Club Lexus Forum, noticed a guy had similiar issues: battery drain over time, gradually leading to inability to start , no CEL, and crank but no start.

Decided to buy a used ECU from the junkyard. Make sure it comes from a engine that runs with no caution lights. (Remember to get the one that is suited for the year your car was manufactured,92-94 have same ECU. Location is under the passenger side carpet, close to the firewall. To locate it, pull the carpeting down from underneath the glovebox, carefully removing it from the console, and on the door side(only to the footplate for the door, peel it back and you will see a black plastic cover about 2x 1 ft. Unscrew the 2 nuts at the bottom and remove) Take the one nut off the left side of the ECU(about 10"x10") and pull up and release back clamp) Unplug the wire bundle plugs(you have to remove the cap and then unscrew the bolt on the large one in order to to pull off the plug.)

Plugged new one in and now had a CEL when ign was turned on. Car fired up about 10 seconds after start of cranking and has run great since!

For those of you who may need an Engine ECU, the forum members have them listed in the classified section, Both this Forum and the Club Lexus website(from $25-150).

There are also repair facilities that can do the job in a week or you can order a reman and ship them your core for faster service, $204 @AUTOECU.COM, shipped.

TOYOLEX PARTS, just google ecu rebuild, they pop up there, Autoecu had the best deal.

Best of luck, glad to have my car back in service.

I did toss that solar charger, it's not worth the chance of it causing problems, thanks.

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my sc400 is doing the samething i have a 92 the car ran fine one day the next it didnt start got it tested for spark and it getting none and i dont hear the fuel pump come on if u figure yours out let me know thanks

Ck my last post on this topic, it took a loooong time for me to fix this thing(less than a $100 though, so I consider it a win)

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  • 1 year later...

I have a '92 SC400 that ran all day relatively fine but the Check Engine Light came on during start and remained on for 5-10 mins at least three of the six times I drove it. I was more concerned with a recent idle issue than the CEL. It would require I hold the gas to keep it from dropping below 400rpm and quitting. Eventually, it would hold 600rpm and be fine. Or it would start and idle at 1200. On another day, It would idle at 1200, gradually increasing to 1800, miss and drop to 1400, rapidly increase to 1800 and repeat. Seemed like once it was warm, it idled normally. The car is out of state and I drive it every month or two and I figured it just didn't like to sit. So when the CEL went away as I drove, I sorta ignored it and hoped for the best. But, when I went out to go to work at 3AM it cranked but didn't start. I won't be back in town to work on the car for a week. What's the best way to proceed if: 1) the CEL comes on with the ign in ON, or 2) the CEL does not come on with the ign key in ON? Or, is it best to just have it towed

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  • 2 years later...
  • 3 weeks later...

HAVE 92 SC 400 ,STOPPED AT LIGHT AND SMOKE CAME UP THROUGHT THE DASH . I TURNED OFF THE KEY , SMOKE STOPPED , CAR WOULD NOT START.

HAVE REMOVED - LOWER DASH ,STEERING WHEEL , IGNITION SWITCH ( FUN GETTING SCREWS OUT ) .

IT CRANKS BUT WON'T START , BUT NO SMOKE WHEN KEY IS TURNED .CAN'T FIND ANY FRIED WIRES .

FUSES UNDER HOOD ARE OK , AND RAIDO WAS WORKING BEFORE I REMOVED IT .

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