SuperNova Posted September 14, 2007 Share Posted September 14, 2007 So when im driving around i notice that the volts gauge goes up and down quite a bit from about 14 to around 10 or lower and nothing is on. I also noticed that i can heard the fuel pump change pitch with the voltage drop or increase. I have an EA81 with a SPFI conversion and a GM Alternator Swap, so i know i have plenty of power. I was thinking it could possibly be the voltage regulator but im not sure. And i figured i would ask and see if anybody knows whats up or has had this problem before. Link to comment Share on other sites More sharing options...
j2coe Posted September 14, 2007 Share Posted September 14, 2007 most parts places will check alternators for free. if the voltage is dropping to 10 while running with nothing on it could be the regulator, easiest to have it checked and remove the doubt then you can look for less obvious things. Link to comment Share on other sites More sharing options...
SuperNova Posted September 14, 2007 Author Share Posted September 14, 2007 most parts places will check alternators for free. if the voltage is dropping to 10 while running with nothing on it could be the regulator, easiest to have it checked and remove the doubt then you can look for less obvious things. Its a brand new GM alternator and its charging at the battery 14+ volts. So i know its not the ALT. Link to comment Share on other sites More sharing options...
nipper Posted September 14, 2007 Share Posted September 14, 2007 Its a brand new GM alternator and its charging at the battery 14+ volts. So i know its not the ALT. No you dont. I just went through an Alt on Blu, it was two months old and went bad. I got one from subaru instead. Volt meters move during the operation of the car. Is it bouncing around at 2000 rpm or higher? nipper Link to comment Share on other sites More sharing options...
j2coe Posted September 14, 2007 Share Posted September 14, 2007 better to test it and the battery they're easy. then you can worry about harder stuff Link to comment Share on other sites More sharing options...
daeron Posted September 15, 2007 Share Posted September 15, 2007 could also be a decaying charging wire, a bad fusible link or connection, bad battery cable/terminal... with the car running, jiggle and twist and bend every plug, and every inch of every wire between the battery, alternator, and fusible link block, as well as wiggling all fusible links in their plugs. Have someone watch the volt meter, or better yet go to harbor freight and get a multimeter on the cheap (under five bucks.) Home depot has the same cheap multimeter for around ten bucks, maybe 15. Even a cheapo multimeter is an invaluable tool to have. Link to comment Share on other sites More sharing options...
SuperNova Posted September 15, 2007 Author Share Posted September 15, 2007 could also be a decaying charging wire, a bad fusible link or connection, bad battery cable/terminal... with the car running, jiggle and twist and bend every plug, and every inch of every wire between the battery, alternator, and fusible link block, as well as wiggling all fusible links in their plugs. Have someone watch the volt meter, or better yet go to harbor freight and get a multimeter on the cheap (under five bucks.) Home depot has the same cheap multimeter for around ten bucks, maybe 15. Even a cheapo multimeter is an invaluable tool to have. Yeah, well good idea but already thought of that. Actually with the new SPFI conversion i just did, i went through everything at the same time. So everything is pretty much new under the hood to the gauges and ecu. Its not something so simple or i would have found the problem by now. But thanks for trying. Link to comment Share on other sites More sharing options...
SuperNova Posted September 15, 2007 Author Share Posted September 15, 2007 No you dont. I just went through an Alt on Blu, it was two months old and went bad. I got one from subaru instead. Volt meters move during the operation of the car. Is it bouncing around at 2000 rpm or higher? nipper Ok, well what type of alt did you have? I have a new, not reman, GM alt hooked to an Optima red top that i have tested a few times to be positive that they are not part of the issue. I Am pretty sure i dont have a problem with the charging system. Thats why i figured voltage regulator and thought i would post to see if anyone has had the same problems also. Link to comment Share on other sites More sharing options...
TomRhere Posted September 15, 2007 Share Posted September 15, 2007 The regulator "IS" part of the charging system... And be it "new" or "re-man" fresh out of the box, or 20 years old doesn't really matter. Things break when they want to.............. Link to comment Share on other sites More sharing options...
Cougar Posted September 15, 2007 Share Posted September 15, 2007 It would be nice to know what the current is doing while the voltage is low. I tend to think that the trouble may be due to a shorted cell in the battery. This would cause a high current surge. If the voltage drops suddenly to 10 volts and then back up then that may be the case. Being an Optima though I wouldn't think that kind of problem would happen but I don't know for sure. Another possibility is a problem with a connection in the main buss wiring, like a fusible connection, as mentioned by Daeron. If it is a wire connection problem then I would think the voltage drop would vary, depending on the connection resistance. Link to comment Share on other sites More sharing options...
daeron Posted September 15, 2007 Share Posted September 15, 2007 check for AC voltage at the battery, step one. Rule out every thing that has not been independently ruled out as the possible source of this problem. You say you have all new wires; I say you have a bunch of un tested connections until you have independently verified them as good, given your current problem status. You ran a new charging wire from the alternator to the fusible link block as a part of your alternator retrofit? or as a part of your SPFI swap? The charging wire typically goes to the link block, and thence to the battery; they share a common connection point to the car's electrical system at the fusible link box if I am not mistaken. (I may be, I don't know YOUR car in particular.. I am just trying to help, not browbeat ) The last thing to do is rule out the simple stuff "intellectually" without testing it. Thats how I beat my head against a poor running engine for two months when, the whole time, it was a beautiful set of spark plugs that I didn't have the money to just replace to cover my tail, that was causing all my grief. (They didn't show up as sparking yellow until the car practically refused to run, and I was out of work for three months surviving on Ramen Noodle. Stop Laughing! ) Link to comment Share on other sites More sharing options...
GeneralDisorder Posted September 15, 2007 Share Posted September 15, 2007 GM single wire or remote sensing? Also the stock guages are known for being crappy - the one in my Brat routinely changes voltage when I slap the cluster near it. GD Link to comment Share on other sites More sharing options...
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