electrical / starting gremlins

jmd2914 · Nov 17, 2007

only symptom is when i go to start the car it will crank once, slowly crank two more times like its going to die, then the car cranks and starts. have no idea why. no corosion on batter or anything like that. any ideas are welcome, mods are in sig.

thanks in advance

Joel

jmd2914 · Nov 17, 2007

**UPDATE**
now the car wont start at all, cranks once or twice slowly then just makes a humming sound. any ideas are welcome and very much appreciated

HISSIN50 · Nov 17, 2007

I would look for a bad battery connection or a failing battery.

It could be the starter too. I just picked up a POS that sat for a year and the starter is toast (and the battery was sulfated - I'm trying to bring it back). Even with a different battery and a running jumper battery, it would crank at 2 RPM a few times and then do nothing.

I'd clean the terminals, replace cables if needed and then make it act up (keep starting it till it does). Then put a jumper battery on and see how it does. Or add a motor ground and see how it does. You should be able to eventually isolate what the issue is by changing one variable.

If needed, get the battery load tested.

Good luck.

jmd2914 · Nov 17, 2007

the battery is a month old. cables are about six months old. could it be something in the 3g wiring? because my volt meter only sits right above the red.

skunk21 · Nov 17, 2007

have the battery load tested(could be shelf bad) or your charging system checked. sounds like the starter is getting what is called "low volt start" or the starter is getting low voltage causing it to turn over slow, in time this will kill a starter.

most of the time it's caused by poor or loose connections, corroded wires but since you just replaced the wires check those connections, especially by the starter. sometimes you can see arcing or smoke by the starter if someone else is turning it over if the connection is loose. also a bad battery, a battery that is to small or doesn't have enough cranking amps, bad starter motor.

HISSIN50 · Nov 17, 2007

Where is the voltage with the car off? 12.6 is about 100% and the percentage of being discharged drops off quick below that. Even 12.0 volts is insufficient IMHO.

If the battery voltage doesnt increase once you start the car up (and it never goes over 12.6 volts), that's a sign the alt is not getting power to the rest of the car.

In your case right now, you probably don't know since it wont start. Just charge it up and see what it reads and what it does. You can check the specific gravity in each cell if you have a 99 cent tester. Then a jumper battery can help further.

One other note: new doesnt always mean 'good'. I only say it because it's frustrating to rule out a part because it's new when in fact the new part was bad. I have brand new batteries fail load tests (before I bought them). Before I started having all new parts tested, I would have them last a couple months (being borderline) and then fail.

Good luck.

skunk21 · Nov 17, 2007

HISSIN50 said:
One other note: new doesnt always mean 'good'. I only say it because it's frustrating to rule out a part because it's new when in fact the new part was bad. I have brand new batteries fail load tests (before I bought them). Before I started having all new parts tested, I would have them last a couple months (being borderline) and then fail.

Good luck.

hehe, we think alike, new don't mean crap, get it tested. the same has happened to me with alts and starters...I learned .

jmd2914 · Nov 18, 2007

so have the alt and the battery tested and go from there?

jmd2914 · Nov 18, 2007

i went out to start the car this morning and it started so i could pull it into the garage. swapped out the starter relay cuz i had it sitting around it started about five more times and then started doing the same thing. i checked the battery before doing so and had 11.6 volts still have it taked down and bench tested?

skunk21 · Nov 18, 2007

check all your cable connections like I posted. have the battery load tested. have your charging system tested. report back.

HISSIN50 · Nov 18, 2007

Agreed with above. 11.6 volts is severely discharged.

jmd2914 · Nov 18, 2007

checked the wiring from alt to the starter relay and battery cables, they have continuity (sp?). had the battery and alt load tested, both checked out fine, battery was just dead. so does this mean i have charging issues? where do i go from here?

HISSIN50 · Nov 18, 2007

I'm not sure how a discharged battery was tested but if both the battery and alt tested ok, it should be a wiring issue.

Knowing voltage with the car off and then running could help.

Good luck.

skunk21 · Nov 19, 2007

hmmm new battery just dead but test out okay. okay. make sure you don't have some time of draw on your battery when the car is off. if the alt is good and putting out true numbers to the battery, then the wiring to the alt is good if it's making to the battery. the battery is discharging the charge therfore junk, bad cell or cells. it's a very simlpe system, the starter is a pig and likes it's high voltage anything less and no good, the weak link, poor connections, weak unhealthy battery, weak charging system causing weak battery, draw on battery causing weak battery. good luck.

jmd2914 · Nov 19, 2007

so what are possible draws on the electrical while the car is off? my fan isnt running when the car is off i cant really think of anything else. im still really new to electrical work so this is all kinda new to me.

HISSIN50 · Nov 19, 2007

jmd2914 said:
so what are possible draws on the electrical while the car is off? my fan isnt running when the car is off i cant really think of anything else. im still really new to electrical work so this is all kinda new to me.

Any number of items can cause a draw. Things like glovebox lights, vanity mirrors, trunk lights, underhood lights, etc can all wipe down a battery in short order if left on 24-7 (because a switch goes bad. It would be like if the light inside your fridge stopped turning off. Unless you could stay in the fridge, it would be tough to know).

Here's a little synopsis on checking current draw (thanks to Saleen0679 who originally posted it). If the readings dont make sense, ensure the positive meter lead is plugged into the correct DMM port. On many meters, you have to use the 3rd port.

Good luck.

jmd2914 · Nov 19, 2007

oh and about the voltage with the car off and when running. when the car is off it was at about 11.6. when it was running with the idle at about 650-700 it was at about 12-12.5 volts. when i revved the car to about 800 it jumped up to 14volts.

skunk21 · Nov 19, 2007

12-12.5 little weak 13-14 best, although one would think the voltage regulator would have the alt kicking high with a battery that low. alt is getting old , still working but again on the slow side. your battery is droppng volts though, check for draw or weak cells in battery, it very well could be the alt isn't keeping up with the battery but I'm not putting $$'s on it. did you get the same size battery? or one with right amount of cold cranking amps for your car? just asking. you got some digging to do.

HISSIN50 · Nov 19, 2007

jmd2914 said:
oh and about the voltage with the car off and when running. when the car is off it was at about 11.6. when it was running with the idle at about 650-700 it was at about 12-12.5 volts. when i revved the car to about 800 it jumped up to 14volts.

Your battery is still in bad shape. I only bring it up because it being so discharged can skew diagnostics.

The alt is definitely putting out, which is good. Voltage readings at idle are tough to interpolate IMHO because everyone's idle setting is a little different (stock tachs and even aftermarket chronograph tachs are tough to interpolate). All in all, if you can achieve 14.4+ volts at about 2K RPM, that's right in the ballpark with optimal alt output.

I still would like to see the battery or parasitic draw issue resolved, especially since your initial issue is an intermittant cranking and low battery voltage with the car off (and volts are up while running).

MHO.
Good luck.

jmd2914 · Nov 19, 2007

where is the voltage regulator on the alt? is it internal for 3g's? how can i check the cells seperately to see if theyre good?

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