sc4 turns over and over but wont start
04-05-09, 01:48 PM
#1
sc4 turns over and over but wont start
Did a search couldn't find anything, this is kinda one of those weird ghostly things. Just seeing if anyone else has had this problem without me doing a lot of diagnosis first. The car turns over but one start plenty of juice, you leave it for a day come back to it and it wont start. I assuming it isn't getting fuel and have an intermediate pump? Maybe pump ecu? Just very strange that it wont start but you let it sit for a while then most of the time it'll start right up. 
04-05-09, 05:15 PM
#2
I kind of had a similar problem one time. Drove to the store, came back and parked it, tried to start later and nothing, 2 hours later started without a hitch. I noticed that I may have parked on some snow, so one side was higher than the other. Maybe this can help?
04-05-09, 09:28 PM
#3
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I have the same random no-start issue with my car.. I bought a new ecu and it fixed the problem for a while, but it's back to the random no-start. The next thing on my list is to inspect all of the grounds..
04-06-09, 12:05 AM
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If you are running into one of it's no-start conditions, see what happens when you put a test light on one of the plug wires. When mine was going through a random no-start, it was not firing the plugs at all.... so whatever was causing the problem was causing the car to not get spark.
04-06-09, 07:38 AM
#6
unfortunately any guess is not even going to be educated with something like this...
you could have something simple like a loose wire on the crank position sensor, or it could be the ECU, or a ground somewhere, or injectors not firing...
basically, when it happens, you need to do some immediate troubleshooting... First, I would pull a spark plug wire and check to see if there is any spark at all, if there is spark, then I would buy a noid light set (relatively cheap) and check for injector pulses (they just plug in between the injector plug and the injector... My bet is that one or both are missing... if both, its simple, most likely cause is the crank position sensor... if its one or the other, report back and we can help from there...
you could have something simple like a loose wire on the crank position sensor, or it could be the ECU, or a ground somewhere, or injectors not firing...
basically, when it happens, you need to do some immediate troubleshooting... First, I would pull a spark plug wire and check to see if there is any spark at all, if there is spark, then I would buy a noid light set (relatively cheap) and check for injector pulses (they just plug in between the injector plug and the injector... My bet is that one or both are missing... if both, its simple, most likely cause is the crank position sensor... if its one or the other, report back and we can help from there...
04-06-09, 10:36 AM
#7
Ok so this morning i go out after i have had the battery charging at 2 amp', because it was run down from all the trying to start. The thing started right up, i don't know how to diagnose this. After i turned it off thought, the fuel pump stayed on and wouldn't shut off. I had it bypassed passed to see if it was the pump ecu but shouldnt it shut off after the ignition switch is in the full off position?
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04-06-09, 10:46 AM
#8
diagnosing a problem that isn't occurring at that exact time is usually right next to impossible...
I have given you a starting point, but you will have to wait until it doesn't start again in order to test anything...
being that it started now, but not before, I would put the wiring and anything else back to as stock as possible and start from there... if it fails to start and the only thing that changed was your fuel pump wiring, then, pretty good chance the fuel pump ecu is the problem... I kinda doubt it, but since you are already there, might as well check it out...
the key to diagnosis is to check or try one thing at a time... once you've eliminated the fuel pump as a possible culprit, then go pull a spark plug wire while cranking (you will need assistance) if there is spark while cranking, then go get a set of noid lights (like this: http://cgi.ebay.com/WILMAR-BOSCH-PFI...em310132032250 double check that though, I don't recall which style our cars require and I'm 1500 miles from mine) plug that in at each or any injector harness and see if the ecu is firing the injectors... if both of the above do not work, then you most likely have a trigger problem - crank position sensor, if one or the other specifically doesn't work, report back, cause each one has a laundry list of things and I don't feel like typing each out... if they both work, then we also need to go from there...
you need three things for an engine to run - compression, fuel and spark... we have compression because it is intermittent... so we have to be missing fuel and / or spark...
I have given you a starting point, but you will have to wait until it doesn't start again in order to test anything...
being that it started now, but not before, I would put the wiring and anything else back to as stock as possible and start from there... if it fails to start and the only thing that changed was your fuel pump wiring, then, pretty good chance the fuel pump ecu is the problem... I kinda doubt it, but since you are already there, might as well check it out...
the key to diagnosis is to check or try one thing at a time... once you've eliminated the fuel pump as a possible culprit, then go pull a spark plug wire while cranking (you will need assistance) if there is spark while cranking, then go get a set of noid lights (like this: http://cgi.ebay.com/WILMAR-BOSCH-PFI...em310132032250 double check that though, I don't recall which style our cars require and I'm 1500 miles from mine) plug that in at each or any injector harness and see if the ecu is firing the injectors... if both of the above do not work, then you most likely have a trigger problem - crank position sensor, if one or the other specifically doesn't work, report back, cause each one has a laundry list of things and I don't feel like typing each out... if they both work, then we also need to go from there...
you need three things for an engine to run - compression, fuel and spark... we have compression because it is intermittent... so we have to be missing fuel and / or spark...
04-14-09, 08:03 PM
#9
It starts right up still afraid it'll do it on me again when i'm not close to home. I found that the little vacuum hose that goes to the valve then to the carbon canister was off. It has been running that way though so you think that could have had something to do with it? I took auto service technology years ago and im having trouble tracking this back.
04-15-09, 04:29 PM
#10
Lexus Test Driver
Alright man this sounds like a on and off issue. My buddy REDPHOENIX had this issue. He had the no start thing going on for awhile. Some days it would up all the time then some days not at all. Does the car crank over or no? Does the car crank ,but doesn't want to fire? Do you by chance hear the backfire coming out of the exhaust? If you are missing either fuel or spark you can test that out. Pull one or all (at different times) depending on if you want to check all wires for spark. Crank the car and see or listen for the zapping noise to something metal in your engine bay. Good to have a friend help you out when doing this. If the spark is all good check for fuel if your car won't start sparay some starter fluid in the intake if you can get it off. Watch out for backfires. If you end up having neither then you have another issue. Here are the common problems with the cars . The ECU's 92-95 have a fault after so many years and you loose either fuel or spark. The fuel pump ecu goes out located by the drivers rear under the b pilar window. Starter is going out after 100,000 miles. If you want to get hold of me quicker instead of PM's hit me up on AIM. Later SHOLEXMAN
04-15-09, 05:16 PM
#11
It cranks but wont fire.
No backfire.
Tried starting fluid, no start.
I have spark, i have fuel.
Bypassed fuel pump ecu to make sure it wasn't and intermediate pump ecu problem.
Put noids on injectors all firing.
Turns over and runs fine now but afraid to drive it.
Maybe main ecu, hard one...
I do not have an egr system or a cold start injector due to it has been supercharged before. It has always run fine without that anyway, its running now haven't got it to NOT start again so far...
No backfire.
Tried starting fluid, no start.
I have spark, i have fuel.
Bypassed fuel pump ecu to make sure it wasn't and intermediate pump ecu problem.
Put noids on injectors all firing.
Turns over and runs fine now but afraid to drive it.
Maybe main ecu, hard one...
I do not have an egr system or a cold start injector due to it has been supercharged before. It has always run fine without that anyway, its running now haven't got it to NOT start again so far...
Alright man this sounds like a on and off issue. My buddy REDPHOENIX had this issue. He had the no start thing going on for awhile. Some days it would up all the time then some days not at all. Does the car crank over or no? Does the car crank ,but doesn't want to fire? Do you by chance hear the backfire coming out of the exhaust? If you are missing either fuel or spark you can test that out. Pull one or all (at different times) depending on if you want to check all wires for spark. Crank the car and see or listen for the zapping noise to something metal in your engine bay. Good to have a friend help you out when doing this. If the spark is all good check for fuel if your car won't start sparay some starter fluid in the intake if you can get it off. Watch out for backfires. If you end up having neither then you have another issue. Here are the common problems with the cars . The ECU's 92-95 have a fault after so many years and you loose either fuel or spark. The fuel pump ecu goes out located by the drivers rear under the b pilar window. Starter is going out after 100,000 miles. If you want to get hold of me quicker instead of PM's hit me up on AIM. Later SHOLEXMAN
04-15-09, 07:03 PM
#12
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got the same problem today. went to pick up the car from the paint shop but it wouldn't start. cranks over, sounds like it tries to start once in a while, no backfire. 
04-16-09, 05:27 AM
#15
because we know it has compression, then when its cranking but not starting, then something is wrong with spark and/or fuel...
noid lights on injectors work, ok - do we know the injectors are actually spraying fuel? is there fuel pressure in the lines? have we checked more than one spark plug? have we pulled the spark plugs to check for extreme fouling?