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Tearin' out the Lean Burn - Gots some questions...
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Author:  Rob Simmons [ Mon Dec 13, 2010 8:20 am ]
Post subject: 
Quote:
Rob

check to see that you have the relay wired in correctly, can you get a test lamp to light on the power out relay terminal when the key is on start?
I likely won't get a chance to get back over there to fiddle until after the new year. :( Now that it's outside and covered with snow my motivation to work on it has decreased accordingly... :oops:

I'll definitely check that when I pop the hood again!

We leave for our trip to Tucson this Saturday.
Author:  Rob Simmons [ Fri Dec 02, 2011 8:57 am ]
Post subject:  1 year later... :-)
Well, I didn't get back to it until now... :roll: :oops:

I popped the hood the other day while I was over at the garage cleaning up some stuff and re-arranging a little.

After getting the GodsRods Duster to fire up with the HEI set up I figured I could get the truck running as well...

I had the ground wire on the wrong side of the HEI module, so I thought I had found the problem...

Nope! Still no spark out of the coil. :(

I have power to the "B" terminal and Coil (+) with the key on, but still no spark out of the coil. I didn't check it with a volt meter. The "B" terminal is the only terminal that has power with the key on.

I re-verified that all of the wiring matches what I have on the Duster.

I used the proper grease that came with the HEI module and it is mounted on the HEI heat sink.

The coil is a brand new MSD Blaster 2 with all new plug wires.

The HEI is brand new as well.

The ground wire runs from the B/C side mounting screw on the HEI module to the Voltage Regulator mounting screw and I scraped the paint off underneath both mounting areas.

Next steps:

1. Test with a volt meter.

2. Use the MSD Blaster 2 coil from the Duster

3. Use the HEI module from the Duster

Questions:

1. Are the "B" terminal and Coil (+) the only locations that should have current with the key on?

2. Which HEI terminals should have current while cranking? (Holding key in the "Start" position)

3. What the heck am I missing!? :x :lol:
Author:  slantzilla [ Fri Dec 02, 2011 9:06 am ]
Post subject: 
Rob, where did you get the "key on" power? Are you sure you have voltage while cranking? Many of the "key on" circuits drop power when cranking.
Author:  SlantSixDan [ Fri Dec 02, 2011 9:12 am ]
Post subject: 
Slantzilla's got a good idea. Try turning the ignition key "on" and then going under the hood and jumping the two starter terminals to each other (carefully with a screwdriver if you haven't got a remote starter button) to crank the engine and see if it starts (or at least if you have spark).
Author:  Rob Simmons [ Fri Dec 02, 2011 9:18 am ]
Post subject: 
Hey Dennis,

I had my test light connected to the negative battery terminal for the ground and held the test light to the spade terminal on the HEI module and to the post on the Coil (+) terminal.

I did not test for power while cranking. I was alone and couldn't reach around to hold the test light and turn the key at the same time. My remote starter broke at Clay City :(

The power is coming from a big red wire from the main harness that attached to the "Hot Spider". That wire now goes only to the Coil (+) and to one of the FLDs on the alternator.

I will take one of the boys with me next time to test for power while cranking and will also test voltage.

If that wire does drop power while cranking, what is a good source to use for power?

Thanks! :D
Author:  Reed [ Fri Dec 02, 2011 9:47 am ]
Post subject: 
The red wire is the right one to use. That is the wire I have used on both of the lean-burn vehicles I have converted to HEI. I like to use the wire that used to feed the lean burn computer.
Author:  Joshie225 [ Fri Dec 02, 2011 9:51 am ]
Post subject: 
I think Reed has the right idea. Use whatever source the factory used even if you're only using it to trigger a relay.
Author:  Rob Simmons [ Fri Dec 02, 2011 9:52 am ]
Post subject: 
Quote:
The easiest way to swap in an HEI ignition on a vehicle that had lean burn is to use the existing wiring. The (-) coil wire stays the (-) coil wire,....
Just going back through everything again to see if I catch something I might have missed and re-read the part above from Reed.

The only wire going to the Coil (-) post is the one from the "C" terminal on the HEI module.

The Duster is the same, just with an additional wire going to the tach.

I don't think I need any other wires to the coil (-). Originally the coil (-) wire went to the Lean Burn (no idea where it went to inside that monster :lol: )

The power source to the coil (+) does come from what was once the "Hot Spider" as mentioned in other posts.

I'll check for power while cranking, but I have a feeling that either one of these new parts (Coil / HEI) is bad or I'm just not getting enough juice.
Author:  DadTruck [ Fri Dec 02, 2011 10:06 am ]
Post subject: 
Rob

if I understand correctly, the motor turns over but does not start, and you have found that there is no voltage at the coil with the ignition key on.

If this is the case, run a jumper wire from the battery to the coil + and turn the key and see if it starts,, if it does,,,,

on these old D trucks,, buried in that tape wrapped bundle of wires that comes from the under hood fire wall connector are a couple of fusible links,, and one of those has blown.

this is one of those,, don't ask how I know this,,

regards
DT
Author:  Rob Simmons [ Fri Dec 02, 2011 11:02 am ]
Post subject: 
Hey John,

There IS power to the coil(+) terminal with the key on. There is no spark coming from the coil wire when cranking though.

The next time I'm over there I'll see if there is still power to the coil while cranking and get some voltage readings.
Author:  Reed [ Fri Dec 02, 2011 11:13 am ]
Post subject: 
Try plugging in the three prong oil pressure idiot light sending unit. Also, verify that the pickup coil in the distributor is functioning.
Author:  DadTruck [ Fri Dec 02, 2011 6:21 pm ]
Post subject: 
well, having power to the coil with the switch on may be the best news that you will get today,,

its either the module, ground, or distributor,, any or all are easier than breaking into that wrapped bundle of wires to find the fusible link,,

sounds close to the same issue that you had a Clay City,, that one sparked once with each key on,, what fixed that one ?
Author:  Rob Simmons [ Sun Dec 04, 2011 3:53 pm ]
Post subject: 
Quote:
what fixed that one ?
A different distributor... :roll:

Shouldn't the coil send spark regardless of the distributor though? I'm not getting any spark out of the coil wire (before the distributor)

Or does the distributor complete the circuit?

I ain't much good at electrical stuff. :oops:
Author:  Reed [ Sun Dec 04, 2011 3:59 pm ]
Post subject: 
The pickup in the distributor is what sends the signal to collapse the field in the ignition coil and send the spark down the wire to the distributor cap. If the pickup in the distributor is not sending the signal, the coil field never collapses and the high voltage current is never sent to the distributor cap.
Author:  Rob Simmons [ Sun Dec 04, 2011 4:57 pm ]
Post subject: 
Thanks Reed. That makes sense.

How can I verify that the pickup coil in the distributor is functioning?

It's been a year since I was last under the hood of this thing. I seem to remember removing one of the sending units (probably the three pronged one). There is still one hooked up with a white wire I believe.

I'll try to get back over there one day this week. It was raining today, so I fiddled with the Duster instead of the truck.
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