| Interesting no-start condition - HEI Ignition [message #227338] |
Mon, 28 October 2013 09:39  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Senior Member |
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Greetings !!
Here's a peculiar one...
I was messing around with my 1973 GMC 23 footer this weekend and decided to hook up the non-operating tachometer. It's and old EQUUS digital display with buttons for Water Temp, Oil Temp, Volts, RPM, Outside Temp, and Inside Temp. The voltage display worked just fine - none of the others did - I just figured things weren't connected to the sending units.
The tach was my first target - and I discovered a disconnected wire at the HEI distributor TACH connection. I couldn't really determine if the wire had broken at the connector or had been cut.
I crimped on a new connector and slid the wire (white) onto the TACH connector of the distributor. Looked perfect - correct length, correct routing...
But - with this wire connected - the engine just cranks and cranks - no starting. And when I disconnect this wire - it fires right up !!
I can see that the wire routes up to the dashboard but I haven't traced it yet.
I figured that the old digital tach display had some wierd electronics that might be affecting things - so I unplugged the display/control unit. All that is in place is the wiring harness... Still the same symptoms.
My second thought is that the wire erroneously grounded by being pinched somewhere.
So... any thoughts as to what could cause this connection to take away my spark ??
I'm expecting questions about the Equus display unit wo I'll look for info and post a picture of it later.
Thanks in advance for any ideas !!
Steve W
Southern California
Steve W
1973 : 23'
Southern California
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| Re: Interesting no-start condition - HEI Ignition [message #227392 is a reply to message #227338] |
Mon, 28 October 2013 14:49  |
GMC Cruse
Messages: 606
Registered: June 2009
Location: SE Michigan
Karma: 3
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Senior Member |
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| SteveW wrote on Mon, 28 October 2013 10:39 |
Greetings !!
Here's a peculiar one...
I was messing around with my 1973 GMC 23 footer this weekend and decided to hook up the non-operating tachometer. It's and old EQUUS digital display with buttons for Water Temp, Oil Temp, Volts, RPM, Outside Temp, and Inside Temp. The voltage display worked just fine - none of the others did - I just figured things weren't connected to the sending units.
The tach was my first target - and I discovered a disconnected wire at the HEI distributor TACH connection. I couldn't really determine if the wire had broken at the connector or had been cut.
I crimped on a new connector and slid the wire (white) onto the TACH connector of the distributor. Looked perfect - correct length, correct routing...
But - with this wire connected - the engine just cranks and cranks - no starting. And when I disconnect this wire - it fires right up !!
I can see that the wire routes up to the dashboard but I haven't traced it yet.
I figured that the old digital tach display had some wierd electronics that might be affecting things - so I unplugged the display/control unit. All that is in place is the wiring harness... Still the same symptoms.
My second thought is that the wire erroneously grounded by being pinched somewhere.
So... any thoughts as to what could cause this connection to take away my spark ??
I'm expecting questions about the Equus display unit wo I'll look for info and post a picture of it later.
Thanks in advance for any ideas !!
Steve W
Southern California
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I too would like to hear some ideas. I had a small block Chevy in a '27 ford that was starting fine with points distributor and Sun tach, replaced points with Pertronix ignition and no spark. Installed a complete Pertronix distributor still no start. Installed a HEI distributor I knew was good and it fired right up. Later I installed the Pertronix distributor again and still no spark until I disconnected the Tach and then it fired right up.
I figure the HEI must take less juice to spark than the Pertronix and for some unknown reason the tach was zapping enough to affect the Pertronix. Tach checked out as good and battery fully charged.
Mike K.
'75 PB
Southeast Michigan
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