TomRhere Posted May 6, 2009 Share Posted May 6, 2009 (edited) its just that my car has occasionally found a state where the engine is running but the idiot lights are still on my thought process is that figuring out what tells those lights to turn off when the car is running will lead me to the source of the problem. The "dash lights ON, and engine running" thing may be random, yes. BUT,,,, it is telling you that your altenator is failing, or atleast the diodes in the alt are failing. edit; that was wierd.. Got knocked "off-line" before I finished typing and hitting the post button. Get back "on-line" 1st line of post is here. ?????? To continue: The fact that the charge light isn't coming "on" has nothing to do with failing diodes in the alt. The alt may very well be putting out enough DC voltage to keep the light "off". The failing diodes allow AC voltage into the electrical system, this is what's making the other dash lights come "on". The random "engine dies/don't start" could be related to a loose connection in the wiring harness, or failing ignition switch (ie; worn contacts). Swap out your alt, then we can help you track down the other issue(s). Edited May 6, 2009 by TomRhere Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 6, 2009 Author Share Posted May 6, 2009 ok popped in a fresh alternator to go with the fresh voltage regulator i had installed. the car starts right up and runs for about 5 minutes at which point the idiot lights come on and the sound of the motor changes. it sounded like it was running a little faster and possibly a little leaner because the sound was more sharp and barking than normal. while the engine was running i checked for AC and DC voltage. for AC i got about .02 V so thats well within normal range and i got a little over 14V DC so that was also good. when the idiot lights came on i re tested for AC and still got about .02 V. sadly i was not able to get a reading for DC before the car died because i jumped in the car and feathered the throttle which kept it alive for a few more seconds. i then let the car sit for a minute after which i was able to get it started but it would not run. could it be that something is failing and telling the fuel pump to shut off ? Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted May 6, 2009 Share Posted May 6, 2009 You might have a short in the wiring to your fuel pump. AFAIK, the fuel pump is run directly off the alternator, with only a fuse in between. I'm guessing you've checked all you fuses, so I would check the resistance between the small alternator wire(?) and the fuel pump power supply, when the engine cuts out. Also I would check the voltage at the pump when the car is running. It may be that you have some wire that expands when it gets hot enough and eventually shorts when it expands enough to touch a ground. Does anybody know if these old subes had aluminum wiring? Cuz that stuff was infamous for heat expansion. Twitch Quote Link to comment Share on other sites More sharing options...
wallaby Posted May 6, 2009 Share Posted May 6, 2009 watching this thread with interest....... my 82 brat died and won't start..... will continue watching Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 6, 2009 Share Posted May 6, 2009 Check the fuses and fusible links to make sure they are ok. Then check to see if the fuel pump is working. You could spray some starter fluid into the intake to see if that makes the engine fire up. Check the fuel filter also as it may be clogged up. Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 7, 2009 Author Share Posted May 7, 2009 all the fuses in the panel are good and all the ones in the wiring that i have found have been good. the weird part is how its a warmed up thing - id be willing to bet that it will fire right up tomorrow morning and run for 5 minutes, the idiot lights will come on for 30 seconds and then the car will die. im guessing that when the idiot lights come on the fuel pump gets killed and thats what actually makes the engine die. are there any breakers in the system that will pop and then reset when they cool off? Quote Link to comment Share on other sites More sharing options...
TomRhere Posted May 7, 2009 Share Posted May 7, 2009 (edited) Sorry I had you replace the alt for no apparent reason now. But as was said, "dash lights "on" with engine running = failing alt". A failing alt can cause all kinds of "wierdness" in the automotive electrical system. But now it seems that all of your issues "are" related. One would need the wiring layout for your year of vehicle to do alot of this, but it can be done without one. For whatever reason, you are loosing some of the "key on" part of the electrical system. It appears from re-reading all of this, that the coil is still getting power, but the rest of the system is losing it, (dashlights "on", fuel pump shutting "off"). When this happens, the engine will continue to run, until the gas in the float bowl is gone, then the engine dies. The feathering of the gas pedal is keeping the engine running by using the accelerator pumps supply of gas. Only thing I can suggest right now is to check all of the wiring harness connectors for proper connections and/or loose fitting wires. Pay attention to those added switches, as the connections there could be the trouble spot. Be sure to check how they are wired into the cars wiring harness also. edit; It could be the added switches aren't of high enough amp rating. The contacts in them are getting "hot" and breaking the connection. Edited May 7, 2009 by TomRhere another thought... Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 7, 2009 Share Posted May 7, 2009 You stated that you checked the fuses and they were ok but how about the fusible links, did you check them? I have to wonder if one of them is getting hot due to a bad connection and causing this trouble. I think you are correct about finding out what is causing the warning lights to turn on and leading you to the real trouble. Unfortunately I have no data that covers the wiring that old. Quote Link to comment Share on other sites More sharing options...
ferox Posted May 7, 2009 Share Posted May 7, 2009 Yeah the fusible links on the '81's are the two red ones that tangle off the battery. Not a good set-up. I switched mine to the protected plastic box from later model years when I removed my voltage regulator. If you haven't switched those out already it would be a good thing to do just on the idea that they are old and flex with car vibrations by dangling there. Sometimes the f. links can be partially melted and function somewhat. I have extra f. links if you want. I don't work by your parents house anymore, but I could probably swing by there on my way to or from my new job and drop some off. Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 7, 2009 Author Share Posted May 7, 2009 (edited) the fuse-able links seem to be good. i started the car today and it ran fine with 14.5V at the battery. i watched the temp gage because it seemed to die when it got to its warmed up mark. sure enough right as it got to its normal warmed up mark the car's volt meter dropped from 14V to 12V and then the idiot lights came on. i re tested voltage while the car was still running with the idiot lights on and got 12.7v. the tachometer was still alive and reading correctly. is there some kind of temp switch to kill the car when things get too hot which might be bad and tripping too early? Edited May 7, 2009 by bicycle_ben Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 7, 2009 Share Posted May 7, 2009 There isn't any kind of temperature kill switch. You cannot just look at wiring and say it is good. You need to verify things are ok using a voltmeter. I suspect that the wiring between the battery and the voltage regulator has a problem. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted May 7, 2009 Share Posted May 7, 2009 After readin this whole thing, Im with TOM on this one. Did you check those switches? Why did you install the switches? Often times those cute little switches are only like 10-15a and thats pushin it. Thay are made for small lights and to run relays. Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 8, 2009 Author Share Posted May 8, 2009 the switches are 30A and i put them in there because i got a key stuck in the tumblers. i just ran the wires from the stock switch which sits behind the tumblers into my switches. all the switches and all the fusable links show continuity on my multi meter. Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted May 8, 2009 Share Posted May 8, 2009 Now are you testing them whan the car is cold, or when the car is running but with the idiot lights on? As was mentioned before, the switch may be fine cold, but when it starts to heat up, you might be having one separate. Twitch Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 8, 2009 Author Share Posted May 8, 2009 if it was my ignition circuit switch that was cutting out the idiot lights would go off and the car would die but the car stays running with the idiot lights on till it runs out of fuel. something is telling the idiot lights to come on and fuel pump to shut off Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted May 8, 2009 Share Posted May 8, 2009 Ok. You make a good point. Have you checked the wiring between the alt and the fuel pump? Have you checked the fuel pump itself? I don't mean to frustrate you, I'm just trying to help. Twitch Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted May 8, 2009 Share Posted May 8, 2009 Do you have a wiring diagram? Im about to confuse everyone. I looked in my diagram, perhaps some of this might help. First the fuel pump appears fed by the voltage regulator. There does not appear to be a FPCU. There is a fuel cut off circuit also run into the voltage regulator, it shows a 5a inline fuse. There is a wire from the ign. resistor to the regulator, Im asuming its from the resistor (signal) because there is a line to the resistor from the ign. control unit. Perhaps there is a problem with this circut. Or as mentioned befor many posts ago, there is a problem with the ignition, or disty. There is a thermo switch (interruptor?) in the solinoid valve circuitry. It is run through a timer as well. The timer is fused but it appears the only thing shard by it and the regulator is the dash lighting. I didnt see where it was fused, but there is a temp on/off device. There is something in the voltage regulator's circuit that is sutting it off. Killing the fuel pump and the charge (and lighting up the dash). I doubt the new regulator would have gone intermittent on you. You seem sure those switches are correct. One switch for acc. one for on. And both on while running, or just one? How do they work? Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 8, 2009 Author Share Posted May 8, 2009 well the car has run 3,000 miles with the switches in there there is one switch for acc, one for ignition and a push button for the starter circuit. when the car is running the acc can be turned off and you loose things like the heater and radio which i dont have but the car keeps running. if you turn the ignition switch off the car turns off. i have wiring diagrams that show a layout which sounds like what you described - a heat switch going into the volt regulator and the volt regulator feeding the fuel pump. the problem is i dont have a full wiring diagram, just a bunch of less complex wiring diagrams which show simplified versions of each system so i cant really tell how things are inter connected. the volt regulator is fresh out of a box so its unlikely to be bad. i guess im going to have to find the heat sensor and see if the car runs with it un plugged or shorted around whichever the non bad state is. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted May 8, 2009 Share Posted May 8, 2009 (edited) The sensor is an interruptor only (or thats how it appears). I doubt its your problem but you could just try disconnecting the harness to the solenoid valve, and trace wires to the sensor. But for that matter it could be the timer too. Have you cycled the switches when this happens to see if it stops? Once it happens does it stay faulty till its cooled off? You should also check the ign resistor and its wiring. The only reason I note the switches is BEEN THERE DONE THAT. Ive made many a problem for myself, and I just want to make sure you dont chase for weeks after something simple that is not the cars fault Edited May 8, 2009 by ihscout54 Quote Link to comment Share on other sites More sharing options...
bicycle_ben Posted May 8, 2009 Author Share Posted May 8, 2009 haha yeah i know what you mean about making problems it first died while in traffic and i shut it off and it started right back up again and ran fine for 30 minutes. then it did it again and i didnt even turn the switches off, i just pop started it because i was still rolling (in traffic again) and again it ran for a while. then it died while on the freeway with no traffic and it wouldnt start right back up so i pulled over and there there happened to be this guy hitch hiking. ordinarily i would have picked the guy up but my car wasnt going to be much help to the guy anyway i let it sit for a minute and it fired back up and ran for a mile and died. i pushed it into a lot and it sat for a few minutes, fied up and ran for a minute and died again. the last two times i have started it, it ran till it warmed up and died. Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 9, 2009 Share Posted May 9, 2009 As Ihscout54 kind of hints at, this problem may be due to a bad wire connection between the battery and the voltage regulator. I think you will find the problem you are having there. You need to make sure that full battery power is getting to the regulator. A bad connection heats up and the resistance can increase causing a bigger voltage drop. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.