I am sure this issue has been beaten to death but I have done my best to diagnose the problem and I want to explain the situation to others to see if there is something I am missing. Now I am by no means an electrical expert, I try my best to learn more and understand it but I think I have a few more classes before I feel confident in my troubleshooting skills. The issue I have seems to be hard starting when cold. The issue seems to be recent although it has occurred in random spurts in the past only to be corrected by a tightening of battery terminals or a wiggle of the leads. I have performed a voltage drop test from the battery to the engine, from the battery to the body and from the engine to the firewall. The body voltage drop was high and there is almost definitely an issue with the ground but I know about this and I would assume a poor body ground would primarily interfere with exterior lights and sometimes other accessory lights but should have no effect on the starting and charging system. The other areas checked out fine and I hope I didn't miss any test points. I have been having this problem ever since I did my 4bbl swap last month. I assume that this is because for that 4bbl swap I removed the ground terminal and may have disturbed whatever setup was working for my car. This lead to a series of poor charging on short trips and a weak battery for cold starts. I replaced both terminals and started with a fresh section of wire stripping back past the corrosion. I only had rust on the wires and terminals and there was no acidic corrosion. The alternator is charging the battery to 15.5 volts at idle so I assume that is within specs for these temperatures. I have suspected the voltage regulator but I assume that if there was an issue there it would either be that the alternators capacity is being limited (which the check at idle seems to disprove) or that the battery is overcharging which doesn't seem to be occurring. I do get some pulsing of the lights at different rpms so I assume the regulator needs to be replaced but again I don't see it affecting the starting and charging system. The only other causes I can see is the battery, which is a brand new interstate battery, the starter which is a possibility but cranks fine when jumped or the battery was freshly trickle charged and then my original thought which was the terminals. I replaced the terminal before I drove home from school today so I won't know if it helped until tomorrow morning but I figured I would post this here to see if there is anything you guys see that I missed. I am hoping I don't have to replace anything big just yet but this summer I will upgrade to an SI alternator and probably replace the starter for the sake of preventative maintenance. Thanks for reading!
take the positive cable off the battery and hook your pos lead from your multimeter to the battery and hook the negative lead on the terminal. the voltage reading will be how much key off draw you have on the battery. you probably have a draw on something more than likely the voltage regulator if everything is wired like the factory has it. or next time you park it . unplug the regulator and plug it in in the morning and see if the battery keeps its charge. 15.5 is too high if you ask me. 13.2-13.8 is good. even 14.
I never thought of that! I am at school right now and I unplugged my alternator and regulator. I will test the car when the weather clears but from what you said it makes perfect sense that either the regulator or alternator is drawing on the battery so I will just keep unplugging them when the car will sit for the night so I don't ruin my battery by the constant deep cycling. Hopefully it isn't already past point of no return P.S. that test procedure you outlined, wouldn't that be measuring for current draw since ammeters are hooked up in series?
You say it started up after doing a carb swap. Are you sure the new carb isn't having issues with the accelerator pump or choke? The problems could be seperate issues from each other.
The new carb has no choke which in itself takes a little finesse to start properly but a weak battery exacerbates this issue as it is harder to properly modulate the throttle without the engine cranking at the appropriate speed. In the time it takes me to find the sweet spot the battery is already drained to 8 volts. Sometimes I get lucky and I'll find it sooner, others I am not so lucky. I am almost positive this is a current draw issue which I would never have thought of if it wasn't for Lonnie. I unplugged the regulator and alternator today and the battery was at 12 volts when I came back 10 hours later. My hunch is that either the regulator is faulty or there is a burnt out diode in the alternator.
well you may be right about the current draw im not positive. im not sure. electrical school was 4 years ago. but im sure it will read the voltage draw the same if there is current there is volts. ohms law ... it takes 1 volt to push 1 amp through 1 ohm of electricity.
unplug your alternator plug and run a jumper wire from the positive post to one of the terminals (not sure which one, just google it) and see what happens. thats a way to bypass the regulator for temporary. if this is wrong to do someone please correct me cause thats how my chevelle is wired up. and my dads firebird.
You are right V= I*R but from what I have learned to measure voltage you connect to the circuit in parallel and to measure current you connect in series http://www.doctronics.co.uk/meter.htm I am sure there is a way to measure voltage draw but I think there is a different test point in which to measure it, I just haven't been motivated enough to go out in the rain and determine it:laugh: Either way I know there is a draw because battery voltage is lower after sitting for a while. The alternator is confirmed to charge the battery sufficiently at idle and at key off no lights or accessories are running. That leave the culprit at either the alternator or regulator but it does me no justice to determine which one as I will be converting to an internally regulated 10SI alternator. Its just nice to know what the issue is after all these frustrating no start episodes. Next electrical task is fixing my body ground which brings up another question; how do you guys route your body ground and where? I run mine next to the battery on the fender.
Thats how to full field the alternator,it will go past 15+volts even with a bad diode.But it will howl like a banshee if one is shorted.That test is to bypass the regulator for diagnosing if it is bad.Dont drive it in full field mode,youll blow up the battery...and your lights...and gauges....ou:
I have always thought it was bearings that caused the howling but I forgot that a burnt diode would cause that too. That must be the issue then. Although I do notice a big difference in output voltage when going off idle to just over 1000rpm, is that indicative of a poor voltage regulator?
Well I did the swap, I now run an internally regulated 10SI alternator. I had one laying around in my garage, had it tested over at Rons auto electric and it was good all except for some bearing play. Turns out the case was worn so Ron replaced it for my for only $20 and even threw in a 10SI pigtail for me. Everything seems to be fine but I still have the slow crank during a cold startup. I trickle charged my battery over night and still had the same issue. I am now set that the starter is also a culprit in my hard starting issue. What are common causes for this and should I have it rebuilt? I will probably take it to Rons as he does good work and is fair in pricing
Checked timing over the weekend and I was around 12* initial. I checked my battery yesterday when I got home after leaving the car for a couple hours and the battery was down to 10 volts. I call up my friend that sold me the battery and he says every interstate battery he has gotten has been faulty. Go figure, all this troubleshooting work and it turns out to be the item one is suposed to inspect first! I just didn't want to believe it was the brand new battery I spent $80 on. I am hoping an IABC will exchange my battery for free as it is well below the 75 month warranty and is even below the 24 month period where all exhanges are free of charge
if you only paid 80 dollars for an interstate battery you either got a puny one or you got a steal we sell them at the shop and they are high dollar.
I buy Interstate blems for my test bench for $40:Brow: But when i buy one for one of my cars(i always seem to be short one?) I buy Dekka made in USA....same as NAPA sells.Best bang for the buck.:beers2: Side note...a battery is only good for 4 years max,i dont care what you guys say that have 7-8 yr old batterys.Thats how i sell alternators,a bad/old battery taxes your charging system.Shhhhhh......
I got the battery at cost from a friend, I think it is normally almost $120. The IABC gave me a brand new battery for free. Turns out two of the cells in my battery completely lost water. They said it was a defect and they can give me a new one. The battery was only a year old at the most and I never let it sit on the car I start my car and drive at least 20 minutes every day
