ok my car is under some serious electrical issues. while driving the voltage will sometimes drop down to under the first line on the volt gauge. and than it sometimes will bounce back up to 13. i just replaced the alternator new battery and all new cables all my connections in those areas are good. i tested the battery to see if it was pulling any amps w/ the car off and it was pulling .18 so i started pulling fuses when i pulled the cigar/horn one it dropped to .08 than when i pulled the defrost seats one it went to zero. well w/ both fuses pulled i started the car and the voltage was still at the first line on the gauge. w/ a volt meter i was seeing 11 volts at the battery w/ the car just running. the car has a misses and you can tell something is not right what could cause my voltage to drop so much. i have a 140 amp alternator and i disconected my stereo to be safe and still no luck. anyone have any advice.

 

Could be a lot of things. Bad ground(s), old/corroded wiring, dying fuel pump, bad contact at the ignition switch.

 

the grounds are all good except have not been able to check the one underneath the car yet. the ignition switch is the factory one w/ 130k miles on it i just had my battery tested and w/ a load put on it, it was showing 8.2 volts so i bought a new one (napa tested it btw) i had them test one of theres and it came up 11.6 under load my buddies work there so i know they weren't trying to sell me something i did not need. threw the new one in and still had the same problem. the fuel pump is a year old if that. it's a walbro 255lph unit.

 

Could it be the engine idle speed is dropping down too low due to another issue causing your low voltage problem? When you replaced the alternator, you also replaced the belt and the tensioner too right? Got a multimeter? Put it on AC volts and measure from the negative battery post to the output post on the alternator and tell us what you read. Don't forget to put it on AC but for this test only.

 

it showed 025 from the alternator to the ground on the battery post. i did not change the belt or tensioner. the belt is however 6 months old if that. at idle the voltes at all connections is 12.2 i did notice that when i put down the e-brake the voltage drops a little more.

 

update. i checked all grounds. including the one that runs from the passenger side motor mount to battery. also i have added a ground from the oil pan to the battery. because the factory one that went to the body was all messed up. i had the car running and pulled fuses that were not esential for having the car running and nothing changed. i wigled all the harness under the dash and the gauge just ever so slightly moved. it still has the problem were when i start the car it is at the first line and when i let down the e-brake the gauge goes half way between the begining line and the first line of the gauge.

 

Measure the voltage across the battery with everything turned off. Then read it while someone cranks it over. Continue to read across it for a few moments after it starts up then increase the load step by step while your reading across it. By that I mean, turn on parking lights then head lights then high beams then the AC compressor and let us know what you see. By the way 0.025 is good so the diodes are ok.

 

I know you have a new fuel pump but did you get the relay harness from Racetronix? A buddy of mine is using the racetronix kit and with the plug and play harness installed he sees at least 1 volt more in the system.

 

i do not have the racetronix kit. another update. i had the car running and turned the turn signals on and they did not work but with the headlamps on they did. turned car off for a bit and started up again and they worked w/ the headlights off. voltage seemed a little bit better. not good by any means but better. my voltage also increases when i turn on the headlights not sure if this is normal. do not have someone here right now to crank over car while measure the volts right now so will get back to you on that tonight. thanks again guys.

 

ttt

 

come on guy's i really need some help here.

 

I'm in the same boat as you are right now and I'm very disheartened to hear you replace the battery, belt, cables, and alt w/ no success. I'm bumping this as I hope you find a answer and possibly be the same thing for myself.

 

I purchased the volt blaster from ram chargers and that bumps up the voltage output 1 volt or more if you need it at WOT.

 

That would be nice but that still doesn't cure the problem. Until he finds the source that's just a band aid. My car never pulled volts and now it does for whatever reason under any kind of load causing the car to sputter but once past 2500 rpms it holds and drops again shortly after.

I find out what the problem is I'll get that volt blaster. I didn't see a increase in voltage w/ my racetronix kit but most others claim they do.

 

ya i have a voltage booster but does not help much. unless the car is all good.