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Electrical

L

LarryK 87

Guest
Ok, Lets try this one on here...

During normal ( non-liquid sunshine days), Engine generally always runs fine, occasionaly right after startup depressing the brake pedal will cause the engine to run a tad rough.
Friday driving home, It was raining, turned on the wipers, and came up to a stop light, engine running REAL rough, release brake... engine settles back to normal, Brake on... bad Idle. Wipers Off.... Depress brake, engine idles normal.

Voltage was around 12.5 or so with wipers and brake on ( possibly dropping, but could not tell). Relase brakes Voltage back up to near 13v or so.

It sounds like a moderate load seems to be pulling the ignition down. I suspect there maybe bad or marginal grounds, and was going to check them this weekend, but cannot seem to figure out how to get the battery out of the car!!! ( sounds simple enough eh!!!) without disassembling the Cruise control diaphram, and support piller that runs over the top of the Battery.

So possibilities are... ????
1. Bad Grounds G101, and 401 ( to start)
2. Altenator simply not putting out suffecient current?
 
B

boblx2a

Guest
Sounds like you may have hit on it Larry. My '85 and '86 both run over 14V with the engine running...........I regularly check the voltage with the engine running while driving and it varies depending on load but it is usually around 14.2 to 14.4 volts on both of them. It is a rare occasion that it drops to 13 volts.

Good luck with it.............
 

jeepie

Well-known member
Joined
Feb 6, 2002
Messages
162
Location
Dunmore, Pa.
Corvette
1991 Coupe Blk/Blk
I would check both battery cables and connections first, they get corroded inside the plastic covers check them and clean them good. There are two grounds right around there, one on the top of the frame on the side of the battery and one that runs from the front of the trannie housing to the frame. You can remove the battery by removing the side cover three bolts inside the wheel well and one bolt on top of cover by the door, and loosen the one bolt under the cover, its a little hard to see but there is one, don't remove it all the way just loosen it enough to slide the cover off.
Your setup should be the same as mine, if not sorry.
 
T

tom_85_vet

Guest
You need to remove the side panel to get the battery out. Since vets are made of fiberglass they seem to have problems with grounds. Check all the grounding straps especally around the engine. Also, I suggest cleaning your battery connectors (wire brush).
Go Luck!!!
 
L

LarryK 87

Guest
ok, the help on the side cover is much appreciated, Tried getting it off yesterday. I Take it with let above mentioned bolts removed, and the bottom one loose, it just slids off? Like a little slide towards the rear, then pull out to the side? Will Try that tonight, Will get a small wire brush, and some no-corrode, and go from there.
And yes i did check the Battery Terms ( Thats how i fixed some really low voltage readings initially )

Thanks all, will let ya know as soon as i get at them ( grounds)
 

jeepie

Well-known member
Joined
Feb 6, 2002
Messages
162
Location
Dunmore, Pa.
Corvette
1991 Coupe Blk/Blk
Yup, the side cover should slide right out to the side. Good luck.
 
L

LarryK 87

Guest
as mentioned above, the cover did in fact slide right off, and i was able to remove the battery, Removed and cleaned the ground on the frame and battery term's, applied a no corrode grease, and bolted every thing back down, All seems ok now, but have not had the same conditions repeat as yet, but did run fine with headlights on lastnight ( i would think that would put on a heavier load than the wipers.)

Well time to get a set of ramps, and get under the car, and chase any other grounds i can find/reach.

Thanks all

BTW voltage still only indicates 12.8 - 13.0 in normal day time driveing have seen it as low as 12.5
 
C

c4ever

Guest
Larry,
I would definitely test the alternator for proper performance. It's a simple test and could save a lot of poking and prodding time.
:w
 
L

LarryK 87

Guest
ok... well guess im gonna have to pull it and have it tested, unless there is some way to load test it on the car.

Rained all this week end ( just after i installed the new outer weather strips on the door :) )

same thing, engine runs like crap until it dries out then runs ok, step on the brake pedal, ignition is momentarily pulled down, starts popping spitting etc.

This am did one other interesting thing, when restarted ( stopped for coffee ) same thing, spitting etc the low pressure warning indicator on the dash came on ( pressure was at 55psi ) Tach was reading 2000 ( idle was much lower ) and tach was not responding to changes in rpm.

One good thing, i always thought the oil pressure was around 42 - 48, but with all the moisture in the air, more elements have "lit up" on the dash and now actually shows it to be in the 50's, guess i have some cold solder joints in the dash, will have to pull it again, and re-flow everything. at least i got my practice in by building the AKM kit.
 

Topless

Well-known member
Joined
Nov 12, 2001
Messages
444
Location
San Diego, CA
Corvette
1992 Convt w/hard top; 2004 Z06 Z16; 1962 327/300
You can get the alternator tested in the car. Some parts places have the machine. Try Schucks/Kragen/Checker (depends on where you live).

A bad diode in the alternator would give enough juice under light loads, but fade under heavy ones.

Mike

ps, have you jump started anyone with the vette?
 
L

LarryK 87

Guest
nope, have not jump started anyone, Heck sometimes im worried i will need the jump start :).
Can't complaint to much, for the shape it seems to be in, have not had to do to much yet, 400.00 on u-joints, 100.00 on a tune up(including IAC), misc. bulbs, and 6ft of vacuum hose. Still starts every day.
 

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