Disconnecting 4 wire distributor stalls engine

[PirateRide]

First post here after lurking and learning for awhile while I've rebuilt my 81 from the ground up - thanks for all the help you guys have been so far!

I am somewhat stumped by my latest attempt to get my engine purring just right and have come to the conclusion that I need outside help. I know that to set the base timing I am supposed to disconnect the four wire harness on the distributor and set the timing. The problem is that as soon as the wire is disconnected, the engine cuts off completely like you turn the ignition key off. I thought maybe the time was so far off that it needed the advance provided by the computer, but swinging the dizzy far in each direction changes nothing - with the 4 wire harness unplugged, the engine just turns over and never makes the slightest attempt at starting.

I've seen plenty of posts where people's cars actually ran better with the harness pulled, but never have I seen anything on it not running at all.

Anyone run into this before or have any ideas?

~Thanks!

 

[Antz81]

As long as you are getting the right connector (which I'm sure you must be since you said it has four wires) then I would guess that the ignition module is faulty. It should take over when unplugged. Everything else would need to be working correctly for it to run with the connector plugged in and unplugged.

 

[PirateRide]

I put in a new Accel module awhile back and it seems to be running fine, but I will put another known good stock OEM module in and see what it does.

 

[toobroketoretire]

I am not familiar with the 81's but the 82's have a ONE WIRE that needs to be disconnected to set the timing. It's a brown 18 gauge wire behind the HEI that has a male/female connector and that wire controls the amount of advance. As the 81's and 82's both are ECM controlled I would think they both use that same brown 18 gauge wire. When you disconnect the 4 wire connector you kill all power to the HEI so that's not the correct one.

 

[Antz81]

I am not familiar with the 81's but the 82's have a ONE WIRE that needs to be disconnected to set the timing. It's a brown 18 gauge wire behind the HEI that has a male/female connector and that wire controls the amount of advance. As the 81's and 82's both are ECM controlled I would think they both use that same brown 18 gauge wire. When you disconnect the 4 wire connector you kill all power to the HEI so that's not the correct one.

Strange my wiring diagram show the 82 as having the same 4 wire connector coming out of the back of the distributor; with the power coming from a single pink wire that connects to the side of the distributor.

 

[toobroketoretire]

Strange my wiring diagram show the 82 as having the same 4 wire connector coming out of the back of the distributor; with the power coming from a single pink wire that connects to the side of the distributor.

What I am trying to say is the 4-wire connector is NOT the one you want to disconnect to set the initial timing. You want to disconnect the SINGLE brown wire that is also behind the HEI. It's an 18 gauge brown wire with male/female connectors and it's located down low almost laying on the top of the bell housing.

 

[Antz81]

What I am trying to say is the 4-wire connector is NOT the one you want to disconnect to set the initial timing. You want to disconnect the SINGLE brown wire that is also behind the HEI. It's an 18 gauge brown wire with male/female connectors and it's located down low almost laying on the top of the bell housing.

$10000 says this wire does not exist on an 81. The only wire there will be than resembles this will be the tan wire to the oil pressure sender. He is CORRECTLY disconnecting the FOUR WIRE CONNECTOR.

 

[toobroketoretire]

$10000 says this wire does not exist on an 81. The only wire there will be than resembles this will be the tan wire to the oil pressure sender. He is CORRECTLY disconnecting the FOUR WIRE CONNECTOR.

Okay, I just did a Google search on setting the timing on an '81 and it DOES say to disconnect the 4-pin connector. So you are right and I am wrong. As the '81's and '82's are both ECM controlled I assumed both had the single wire EST wire that had to be disconnected.

 

[toobroketoretire]

Now back to the OP's question about why his engine is stalling when he disconnects the 4-pin connector. It's possible the female spade connectors on the internal wires have opened up and aren't making a good contact. I have had to use little needle-nose pliers to squeeze those terminals together so they would plug in firmly. I have also found the black ground wire terminal was crimped on the wire's insulation and not the copper wire itself.

 

[Antz81]

It's possible the female spade connectors on the internal wires have opened up and aren't making a good contact. I have had to use little needle-nose pliers to squeeze those terminals together so they would plug in firmly.

The number of times I've found spade connectors have this problem is crazy; not come across too many on the vette though. (I also use the same solution when possible) Heat only makes the problem worse.
Crazy thing is manufacturers of heater elements still fit them to their elements.:ugh The number of elements I come across that have this problem after only a few years is just stupid.

 

[toobroketoretire]

If you happen to have a spare module try it and see if your engine will continue to run. Every HEI owner should carry a spare module anyway so it would be worth buying one. Just don't buy a Chinese cheapie because they don't last very long.