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92 Sc 400 Intermittent Starting Problem


Beak42
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Hi Everyone,

I am new to the forum. Have owned a 92 SC4 for 13 satisfying years with nothing more than rountine maintainance. 134,000 miles. Now I have this starting problem perplexing 2 Lexus dealers and an independent Lexus specialist. The car will be fine for days - weeks then just not start. It can be after a long or short drive. Sometimes it starts an hour later, sometimes after all night, and sometimes it takes 2 days before it will start. So I'll have it towed, and it always has started when it got to the shop the last six towings. They have replaced fuel pump and fuel pump control module without help. The last time the car didn't start it was actually at the dealer, near the end of the workday, and they said there was no firing voltage and no fuel pump pressure. Before they could replace anything, the next morning it started again and they could go no further. The car performs flawlessly until you turn it off, then it just won't fire, if it's going to do it's thing. The starter and battery are recent replacement, and fine. ANY IDEAS????

Andy

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When it does not start, I assume that it cranks but the engine does not run. First, I would think that they read the computer code and see if there's any code. Second, when it does not start, I assume that they check for fuel pressure then check for sparks. If there's no spark, they want to check the ignition coils and see if they are in spec. Then they want to trace back from there...computer or any other inputs that causes no spark. It does not hurt to check the compression either because you need spark, fuel, and compression for a combustion engine to work.

The symptom sounds like heat related. After you run your car then let it sits for awhile, heat from engine or exhaust transfers to nearby component.

Once, I had a problem with a difference car (not Lexus) which had trouble starting when hot. The problem was the starter solenoid which was located near the exhaust.

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Thanks for your thoughts. There are no codes being set acc. to both the Lexus dealer and the independent specialist. Got the car back today from the dealer, running of course, who flat out told me" its too old and we won't work on it anymore, all we'd be able to do is start changing out parts". Perhaps it is heat related, at least in part, but several times it wouldn't start even after cooling overnight. The independent mentioned a relay too - that apparently supplies power to both the ignition and fuel systems. Really perplexing.

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.
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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.

When that happens, I would think that they want to check each spark plug wires and see if they have spark. If not, trace back to ignition coil, ECU, ... A low tech solution, remove each spark plug and see if it's wet from fuel; that means there's no spark goes to it.

For fuel, they can check the signal at each injector, fuel pressure, fuel pressure regulator, fuel return line.

Hope you get it fix. Hope you find the solution for it.

Thi

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.

When that happens, I would think that they want to check each spark plug wires and see if they have spark. If not, trace back to ignition coil, ECU, ... A low tech solution, remove each spark plug and see if it's wet from fuel; that means there's no spark goes to it.

For fuel, they can check the signal at each injector, fuel pressure, fuel pressure regulator, fuel return line.

Hope you get it fix. Hope you find the solution for it.

Thi

Well, my guy thinks he has narrowed this down to the ECM ($1200) ouch!! He has determined:

* NO FUEL PRESSURE

* NO SPARK

* NO INJECTOR PULSE

Can anyone recommend where I might get this computer for less $$????? And if this sounds likely to be my problem???

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.

When that happens, I would think that they want to check each spark plug wires and see if they have spark. If not, trace back to ignition coil, ECU, ... A low tech solution, remove each spark plug and see if it's wet from fuel; that means there's no spark goes to it.

For fuel, they can check the signal at each injector, fuel pressure, fuel pressure regulator, fuel return line.

Hope you get it fix. Hope you find the solution for it.

Thi

Well, my guy thinks he has narrowed this down to the ECM ($1200) ouch!! He has determined:

* NO FUEL PRESSURE

* NO SPARK

* NO INJECTOR PULSE

Can anyone recommend where I might get this computer for less $$????? And if this sounds likely to be my problem???

If that's a dealer or some independence shop, you want them to guarantee that's the problem; otherwise, you want the money back, written agreement. If you want new part, I ordered some parts through "ParkPlacePlanoParts.com/Lexus" and have good luck with them, plus they are much cheaper than my local dealer. If you don't need a California ECM, they sell one for $752 (1992 model). Go in the catalog and search for ECM. With electronic part, be careful because they usually don't take it back once you buy it. I talked with them on the phone before and they are nice and helpful.

Other option would be local junk yard, make sure you can return it if that's not the problem. Unless it's a lot cheaper than the dealer mentioned above, you'll be probably better buying it new.

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.

When that happens, I would think that they want to check each spark plug wires and see if they have spark. If not, trace back to ignition coil, ECU, ... A low tech solution, remove each spark plug and see if it's wet from fuel; that means there's no spark goes to it.

For fuel, they can check the signal at each injector, fuel pressure, fuel pressure regulator, fuel return line.

Hope you get it fix. Hope you find the solution for it.

Thi

Well, my guy thinks he has narrowed this down to the ECM ($1200) ouch!! He has determined:

* NO FUEL PRESSURE

* NO SPARK

* NO INJECTOR PULSE

Can anyone recommend where I might get this computer for less $$????? And if this sounds likely to be my problem???

If that's a dealer or some independence shop, you want them to guarantee that's the problem; otherwise, you want the money back, written agreement. If you want new part, I ordered some parts through "ParkPlacePlanoParts.com/Lexus" and have good luck with them, plus they are much cheaper than my local dealer. If you don't need a California ECM, they sell one for $752 (1992 model). Go in the catalog and search for ECM. With electronic part, be careful because they usually don't take it back once you buy it. I talked with them on the phone before and they are nice and helpful.

Other option would be local junk yard, make sure you can return it if that's not the problem. Unless it's a lot cheaper than the dealer mentioned above, you'll be probably better buying it new.

Try this place. Lots of info on their website. http://www.ecmtogo.com/

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Ok, if you cannot start it even after seating overnight, that's one more data point. When you say it does not start, does the engine crank or there's no sound or just clicking from the starter solenoid? When that happen, how do you get it to start again?

Thi

The engine cranks fine. The starter and battery are new. When its malfunctioning, it just won't fire. Not even once. It's as if you had no fire to the spark plugs but as I undersatnd it lack of fuel pressure could do the same thing. The problem is the malfunction is intermittant - it recurs variably after 1,2 days or it waits a week or a month. Then - it just won't start. Absolutely without warning. Car can be running fine, stop to get gas or run and errand and then it just won't start.

I am having the exact problem with my 94 ls. Mechanic is telling me it's the ECM but I'm not convinced. I have 188K miles and it's never failed to start right up until last week after work - starter would crank and crank but no fire. Left it at work and next day at lunch tried it again and it fired right up and ran great. Drove it home in the evening no problem, then did a fillup and to the grocery - came out of the store and it would not hit a lick! I'm browsing through this forum for any ideas - Because the problem is intermittent, it doesn't appear to me to be the computer - wouldn't a bad computer cause it to never crank?

On a side note - when I came out of the grocery and car failed to crank, I found a puddle of gasoline under my car at the gas door. I didn't overfill the tank - what would cause this? Thanks for any help you guys - I love my car and want to keep it, but I can't afford to let the mehanic start changing out parts till he finds the right problem.

Interesting! Well, I have no gas leak, but maybe you have a different problem. The mechanics wanted to start changing out parts for me too with me funding the research!! First they changed the fuel pump, telling me it had low fuel pressure. No change. Then they changed the "fuel pump control module", for about $550, no change. At least I got a refund for that. Its at the shop again and they want to change the plugs, wires, cap and rotor. I really don't think that will fix it either since the engine runs perfectly smooth when it runs.

When that happens, I would think that they want to check each spark plug wires and see if they have spark. If not, trace back to ignition coil, ECU, ... A low tech solution, remove each spark plug and see if it's wet from fuel; that means there's no spark goes to it.

For fuel, they can check the signal at each injector, fuel pressure, fuel pressure regulator, fuel return line.

Hope you get it fix. Hope you find the solution for it.

Thi

Well, my guy thinks he has narrowed this down to the ECM ($1200) ouch!! He has determined:

* NO FUEL PRESSURE

* NO SPARK

* NO INJECTOR PULSE

Can anyone recommend where I might get this computer for less $$????? And if this sounds likely to be my problem???

If that's a dealer or some independence shop, you want them to guarantee that's the problem; otherwise, you want the money back, written agreement. If you want new part, I ordered some parts through "ParkPlacePlanoParts.com/Lexus" and have good luck with them, plus they are much cheaper than my local dealer. If you don't need a California ECM, they sell one for $752 (1992 model). Go in the catalog and search for ECM. With electronic part, be careful because they usually don't take it back once you buy it. I talked with them on the phone before and they are nice and helpful.

Other option would be local junk yard, make sure you can return it if that's not the problem. Unless it's a lot cheaper than the dealer mentioned above, you'll be probably better buying it new.

Try this place. Lots of info on their website. http://www.ecmtogo.com/

Well it finally failed again at the independent shop and they switched out a battery voltage relay and the main ECU and it still didn't start! So, considerable new info but still no solution.

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  • 2 months later...
  • 1 month later...
Did you ever get your SC fixed? I am having the same problem and am interested what was the actual fix??!! Thanks in advance.

Anyone who posted on this particular topic have any good fixes for this particular problem? Please help!!!

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