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  • April 19, 2024, 10:36:48 AM

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Author Topic: Ignition key "start" position does not always power the ignition.  (Read 6923 times)

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Offline flyamerican

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Working on someone else's Eagle and when you first try to start it, the engine cranks fine but won't fire until you let the switch spring back from "start" to "run".  When the engine has run awhile, it seems to work normally (fires while you're cranking).  I replaced the ignition switch - no help.  Then replaced the solenoid by the battery - no help.  Might try grounding the extra pin under the solenoid to see if problem still exists.  Anyone seen this condition?  Thanks.

Offline eaglebeek

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Re: Ignition key "start" position does not always power the ignition.
« Reply #1 on: December 12, 2014, 08:08:51 AM »
The extra pin under the solenoid is grounded by the neutral/backup light switch on the automatic transmission. If that ground isn't present the circuit logic "thinks" the transmission isn't in neutral or park and the starter won't crank.

As for the cold start problem, next time when it's cold turn on the ignition but don't start it. Use a voltmeter to read the voltage at the "+" terminal on the ignition coil. It should be 6 to 8 volts. Now have a helper turn the switch to start while you're still on the "+" terminal. While cranking you should have full battery voltage.

If readings are different there's a bad wire or poor connection in the harness between the switch and the coil, or the starter solenoid isn't providing the resistor bypass circuit. Post up what you find out. This is one I haven't seen in an Eagle :eagle:
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Offline Amc1320

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Re: Ignition key "start" position does not always power the ignition.
« Reply #2 on: December 12, 2014, 01:55:45 PM »
thanks for posting this flyamerican, I having the exact same issue. It only seems to happen on cold mornings during first start of the day

It turns over fine, starter works, but it will only try to "catch" just as you left the key go and it goes back to "run" position, the problem is by then the engine isn't spinning enough for it to run. There doesn't seem to be voltage to the coil in "start" position, or not enough

A couple weeks ago we cleaned up all the connections on the solenoid and it went away, I thought we were good. But this week it did it again on a cold morning. However once it starts for the day and warms up its seems to be fine after that.

I figure its in the resistor bypass somehow, looking forward to comments on this topic
Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline AMCLOVER258

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Re: Ignition key "start" position does not always power the ignition.
« Reply #3 on: December 12, 2014, 02:25:12 PM »
My eagle does that and i have to hold the shifter all the up in park and crank for drop it to neutral.. Sometimes the safety switch thingy doesn't engage.

Offline carnuck

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Re: Ignition key "start" position does not always power the ignition.
« Reply #4 on: December 12, 2014, 03:44:52 PM »
The NSS only affects cranking of the motor and backup lights. If the motor is spinning, then the NSS is doing it's job. Try this: Don't turn the key quite as far into start. Just till it barely cranks and see if it catches. The solenoid has an ignition pickup on it (contact marked "I") and you should check first to see if the wire to it has power with the key on. (it should be about 8-10 volts) If it does, then the wiring should be okay. The solenoid contact should come to life while cranking. You can check with just a test light. If you have a voltmeter (I have a digital cheapie from Harbor Freight) you can check the power from the battery when cranking. Less than 10 volts means the battery is too weak for the coil to make strong spark.
   I changed my ignition coil out (if you don't have a GM HEI dist or the TFI upgrade) for a Napa IC12 or the cheaper IC12SB which has better coil output voltage and got rid of the horseshoe connector which is a corrosion magnet and spark killer. (just make sure you have it the right way around or the sparkplugs will fire backwards, causing poor spark)
   If you still have a no-start issue, then test for spark. Bad plugwires or especially a bad coil wire can cause no-start. Crud on the coil "cone" can cause arcing, killing spark. Same with the dist cap. Corrosion inside coupled with material stuck to the outside or inside can cause arcing. I do NOT like aluminum contact caps because they don't last 1/2 as long as brass ones. The ignition rotor can also arc or track, drawing spark away.
   If the choke doesn't close almost all the way, then fuel may not be drawn in and the lean condition won't start (flooding from a too tightly closed choke can do it too) I pump the gas 3 times when it's cold out and without my foot on the gas, it fires right up. More or less pumping means no start. If the fuel filter with 3 lines is used, you have to make sure the bypass line is in the top position or gas will drain back overnight.
   That should get you started (barring other issues)
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Offline 1985amceagle

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Re: Ignition key "start" position does not always power the ignition.
« Reply #5 on: December 12, 2014, 10:12:28 PM »
I am going to have to look at the wiring diagrams, but I wonder if the ICM was what controlled voltage, as I think I remember seeing that the ICM had a start position input.
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Offline flyamerican

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Re: Ignition key "start" position does not always power the ignition.
« Reply #6 on: December 19, 2014, 11:40:45 AM »
Thanks for all the helpful replies, folks!  Here's what I found, so far.  First, someone before me had put in a wire to fire up the choke heater from the yellow coil lead.  I'd seen that before but wasn't focused on the starting problem at the time.  Now when I looked at it I thought that was surely what was sucking voltage from the ignition during start.  I reconnected the original choke wire, which had been cut and left hanging.  It works fine - probably someone didn't realize it needs oil pressure to get voltage, and thought it was open.

But that did not fix the start problem.  Later I replaced the coil and distributor cap with known good ones I had, because of an intermittent ignition miss.  I also put on new spark plug wires.  That fixed the miss and It seems like it has also solved the no-fire-in-start-position problem, but time will tell.  I'm thinking it was the old coil.  It did pass the resistance tests, but its behavior can be very temperature dependent according to the TSM.  Will update the thread if I have more trouble with this.

Offline Amc1320

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Re: Ignition key "start" position does not always power the ignition.
« Reply #7 on: December 28, 2014, 05:16:56 PM »
I'm still having this problem , no voltage in start position, or not enough anyway. Something seems to be stealing the voltage

It tries to catch just as the key goes back to run

I'm working on cleaning up and checking grounds, will try new coil tomorrow and see if that helps

Any other ideas?
Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline Mernsy

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Re: Ignition key "start" position does not always power the ignition.
« Reply #8 on: December 28, 2014, 05:33:59 PM »
Something similar happened to me when I mixed up the wires at the top of the starter solenoid...just saying...

Offline carnuck

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Re: Ignition key "start" position does not always power the ignition.
« Reply #9 on: December 29, 2014, 12:44:40 AM »
Turn the key much slower to start and see if that works.
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Offline rmick

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Re: Ignition key "start" position does not always power the ignition.
« Reply #10 on: December 29, 2014, 12:34:09 PM »
In the start position the coil gets 12 volts power from the start relay once the key is released to the run position power gets to the coil form the ignition switch Check the start solenoid for out put to the coil while cranking or run a jumper from the battery to the coil and see if it will start http://amceaglesden.com/guide/6_Cylinder_Engine_Wiring_Schematic
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Offline eaglefreek

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Re: Ignition key "start" position does not always power the ignition.
« Reply #11 on: December 29, 2014, 12:56:19 PM »
I'm still having this problem , no voltage in start position, or not enough anyway. Something seems to be stealing the voltage

It tries to catch just as the key goes back to run

I'm working on cleaning up and checking grounds, will try new coil tomorrow and see if that helps

Any other ideas?
Rob, since you have an HEI distributor, your resistor wire should have be taken out of the loop since the HEI should be fed 12v at all times. Find another wire that is 12v+ when the key is in the start and run position, run it to the distributor and see if it fixes your problem.
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Offline Amc1320

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Re: Ignition key "start" position does not always power the ignition.
« Reply #12 on: December 29, 2014, 04:37:14 PM »
This isn't on mine, with the HEI its pretty easy and I have zero issues with this

this is on the 83 wagon that is my son in laws, its bone stock 1983 version

Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline Amc1320

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Re: Ignition key "start" position does not always power the ignition.
« Reply #13 on: December 30, 2014, 10:36:43 PM »
Sorry to hijack this thread flyamerican

Today I replaced the negative battery cable, the old one looked suspect. I got one of the ones that also has a separate lead that I ran to the body for further grounding

The problem disappeared immediately and it started right up, hopefully it was a poor ground issue and it's now all fixed

Thanks as well for the help
Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

 

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