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Topic: HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

in Forum: C3 Electrical

HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 8:53am Message 1 of 13
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baton rouge, LA - USA
Joined: 8/12/2006
Posts: 391
Vette(s): 1981 dark metallic blue, dark doeskin leather interior, mirrored glass T Tops, 330hp/350ci GMPP crate engine, billeted aluminum serpentine system, Dewitts with dual spalls
I have an 81 that is showing 11.75 volts at the battery and under 11.75 at the choke with the key in the on position.  I did not crank the car yet!  The choke has not been properly operating at this time, see below.  I put a GM crate engine in the vehicle, cut the CCC out but kept the electric choke.
 
To make matters more confusing, I have a 600 cfm Edelbrock Carb and in the Carb users manual, it says that the choke should not be connected to the alternator.  IF you look in the 81 shop manual, apparently the electric choke is wired in the alternator loop.
 
Anyone run across this issue and what did you do to rectify?  We don't get very cold down here in the swamp and I had originally installed a manual choke set up, but the mechanic that works on our co. trucks insisted I install an electric choke on the vehicle over 2 years ago.  It has recently started acting up.
 
The issue is the choke never really fully opens when warmed up and the dude sporadically idles high at stop signs, etc.  I would think if the fuse were blown or the choke heater relay were bad, I would have no volts at the choke.  I don't think I have a vacuum problem as everything works fine and I have great braking.
 
Any suggestions would help!
 
Thanks and best wishes for the new year!
 
gurtzWink 



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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 9:33am Message 2 of 13
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Duncanville, TX - USA
Joined: 11/8/2003
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HNY yerself!!
The choke is fed 12v(or batt voltage) key on. The choke coil acts as a heating element. As it heats up, the coil expands, and opens the choke blade. To do this, the coil must provide a ground(resistance), which in turn heats the coil up.
No voltage at the coil would indeed mean a break in the power flow, such as a fuse, or bad connection. This will normally turn on the "Check Engine" light, but if you have eliminated the ECM, your's prolly won't do that.
Now...you have (system)voltage at the coil terminal, so we know there is power. That voltage should be going to ground thru the choke coil, which is what creates the heat that makes it un-coil, and open the choke blade on the car. Whut we've got heah, is, failure to terminate. Apparently, the choke coil is not fully grounding, and that is causing the problems. The coil inside the choke housing can break, or it could have just become loose enough to not fully provide a ground.
You might take the cover off of the coil, and have a peek inside. Sometimes, there is enough corrosion to cause this, too.
hth


Joel Adams
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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 10:35am Message 3 of 13
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baton rouge, LA - USA
Joined: 8/12/2006
Posts: 391
Vette(s): 1981 dark metallic blue, dark doeskin leather interior, mirrored glass T Tops, 330hp/350ci GMPP crate engine, billeted aluminum serpentine system, Dewitts with dual spalls
Joel:
 
I do have 13.85 volts at the battery with da car running and 8.75 at the choke.  I pulled the fuse and it is not blown.
 
The mechanic did wire the ground for the choke to the carburetor.  I wonder if that is the problem. 
 
Please let me know what you think.  I did pull the choke apart earlier and the coil is not broken and very clean.
 
As always, thanks for your help! 
 
g



HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 11:08am Message 4 of 13
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HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
I've used an Edelbrock 600 CFM w/electric choke on my 327  for a few years and the ground wire went right to a carb stud. That should not be a problem. As long as you've got good ground straps the engine, the carb should be just as good a ground as any other part.
 
It sounds like there's an issue with the IGN wire going to the choke. To prove it out, you could try running a wire from an open ignition port on the fuse block to the carb (first see if you're getting 12V there with the car running). If that fixes the problem, you've got a gremlin in the wiring.
 
Let us know how you make out.
 
Paul
 
 



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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 12:41pm Message 5 of 13
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baton rouge, LA - USA
Joined: 8/12/2006
Posts: 391
Vette(s): 1981 dark metallic blue, dark doeskin leather interior, mirrored glass T Tops, 330hp/350ci GMPP crate engine, billeted aluminum serpentine system, Dewitts with dual spalls
Will do and thanks for the advice.  Not getting back on it till Saturday, but will  let you know!
 
Thanks again!  



HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 2:43pm Message 6 of 13
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WEST SENECA, NY - USA
Joined: 12/3/2001
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Vette(s): 1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.
I had to run a new 12v ignition sourced wire to the choke. The original choke wire on your '81 will not provide enough voltage to operate the aftermarket choke. I believe there is a resistor within the circuit. But whatever the case is, it won't work.
Been there, done that with mine.  




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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 4:32pm Message 7 of 13
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Without looking at the wiring diagram, I believe the choke voltage was provided by the alternator feed, and the choke ground provided by the ECM...I do know a malfunction in the choke circuit, whether by the choke itself, or the radio, will turn on the Choke light.
But I digest...
The choke should have system(12v) voltage to work on pretty much any aftermarket, electrical choke.


Joel Adams
C3VR Lifetime Member #56    

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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 6:42pm Message 8 of 13
Former Member
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baton rouge, LA - USA
Joined: 8/12/2006
Posts: 391
Vette(s): 1981 dark metallic blue, dark doeskin leather interior, mirrored glass T Tops, 330hp/350ci GMPP crate engine, billeted aluminum serpentine system, Dewitts with dual spalls
What ignition source would you guys recommend and I assume from the beloved hard to get to fuse box?  


HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 7:30pm Message 9 of 13
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HOWELL, NJ - USA
Joined: 5/18/2004
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Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
If you haven't used them already, there are usually a couple of open ignition ports on the fuse box. With the key in the "Run" position, check with a test light or voltmeter to see if you have power. Then with the key in the "Off" position, if there's no longer any juice, that should be a good 12V ignition source.
 
These ports are usually towared the bottom outside edges of the fuse box.
 
Keep us posted!! Big%20smile



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HAPPY NEW YEAR Fellow c3 lovers and choke electrical question

Posted: 1/1/09 8:32pm Message 10 of 13
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CUYAHOGA FALLS, OH - USA
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Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
The best way to wire an aftermarket choke is with a relay.  An ignition signal turns on the relay which provides direct battery (better yet alternator) power to the choke itself.  And yes, the ground is important.   The common failure is the choke heater in the coil itself.
 
If it is wired directly to power without a relay to control it, it will never shut off and run the battery down, as well as never allowing the choke to close.  If it is off the ignition alone it may not have enough amperage to operate.



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