Start, but won't run 84 L-jet (new title)
03-05-2009, 08:06 PM
#16
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03-05-2009, 10:14 PM
#17
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Thread Starter
Wow! Thanks for the replies. I will check them all out on saturday and report back my findings. You guys are tremendously helpful and I am extremely grateful.
03-05-2009, 11:17 PM
#18
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Thread Starter
You may have a bad ballast resistor. Instead of running with the starter engaged, see if you have power at the feed end of the resistor(in the pic, top terminal of 0.4Ω resistor.). This power comes from a tap between the 15 pin of the ignition control box and the 15 pin of the ignition switch. Looks like CE panel connectors A4 and A5.
I pulled the resistors to measure them.
The 0.4 Ohm should be 0.35 to 0.45 Ohms; measured at 0.7 ohms
The 0.6 Ohm should be 0.55 to 0.65 Ohms; measured at 0.9 Ohms
The wire terminals looked brittle and slightly melted.
Do you think those values are far enough off? I will check wire to coil and igniton unit also.
03-06-2009, 12:06 AM
#19
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Thread Starter
More 16V ignition values:
Coil primary resistance term 1 to term 15 should be 0.33 to 0.46; measured 0.60 ohms
Coil secondary resistance term 1 to term 4 should be 7 to 12K Ohms; measured 9K Ohms
Measured voltage at ignition coil term 15 against ground should be at least 3 V; measured 0.93V with ignition turned on.
(jump post voltage 11.78V)
I think you have pointed me in the right direction. I will trace wires and voltages to see where the voltage drop is located, but I think it is in the resistors and ignition coil.
Any thoughts?
Thanks again
Coil primary resistance term 1 to term 15 should be 0.33 to 0.46; measured 0.60 ohms
Coil secondary resistance term 1 to term 4 should be 7 to 12K Ohms; measured 9K Ohms
Measured voltage at ignition coil term 15 against ground should be at least 3 V; measured 0.93V with ignition turned on.
(jump post voltage 11.78V)
I think you have pointed me in the right direction. I will trace wires and voltages to see where the voltage drop is located, but I think it is in the resistors and ignition coil.
Any thoughts?
Thanks again
03-06-2009, 02:56 AM
#20
Rennlist Member
None of the numbers are outrageous, if your meter isn't reading high then it points to a marginal coil, but that's likely not your problem. The big problem here is the .93V at the coil. What is the voltage at the point that I initially mentioned -- the other side of the ballast resistor, and at CE panel A4 & 5? If that checks out to be battery voltage, that points to the resistors and/or coil. If it's low, then it's a problematic connection in the panel, ignition switch, or wires between.
Also, check the battery in your meter. If the battery is low, that would explain the high resistance readings across the board, especially if it's an analog meter.
Also, check the battery in your meter. If the battery is low, that would explain the high resistance readings across the board, especially if it's an analog meter.
03-06-2009, 11:22 PM
#21
Rennlist Member
Thread Starter
None of the numbers are outrageous, if your meter isn't reading high then it points to a marginal coil, but that's likely not your problem. The big problem here is the .93V at the coil. What is the voltage at the point that I initially mentioned -- the other side of the ballast resistor, and at CE panel A4 & 5? If that checks out to be battery voltage, that points to the resistors and/or coil. If it's low, then it's a problematic connection in the panel, ignition switch, or wires between.
Also, check the battery in your meter. If the battery is low, that would explain the high resistance readings across the board, especially if it's an analog meter.
Also, check the battery in your meter. If the battery is low, that would explain the high resistance readings across the board, especially if it's an analog meter.
03-06-2009, 11:45 PM
#23
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Thread Starter
03-07-2009, 03:55 AM
#24
Rennlist Member
The resistor should get warm. I have about 10.2v at that test point. The difference would not be enough to triple the voltage. If you get battery voltage at that same terminal when it's disconnected from the resistor, then the rest of the wiring is fine. You can confirm by connecting that terminal straight to the jump post to see what happens to the voltage. If no change, the problem is probably the resistors and/or coil(assuming your meter is accurate). If you get closer to 10-10.5 V, then there is a problem with a connection upstream of that point.
I would add a wire as a last resort. Chances are your wiring is fine and it's a connector or the ignition switch that's acting up.
I could lend you a working coil to test with, but it's not a good replacement -- it's leaking. Better to throw borrowed or used parts at it while troubleshooting, then buy new when you're sure what needs replacing.
I would add a wire as a last resort. Chances are your wiring is fine and it's a connector or the ignition switch that's acting up.
I could lend you a working coil to test with, but it's not a good replacement -- it's leaking. Better to throw borrowed or used parts at it while troubleshooting, then buy new when you're sure what needs replacing.
03-07-2009, 10:15 AM
#25
Rennlist Member
Thread Starter
The resistor should get warm. I have about 10.2v at that test point. The difference would not be enough to triple the voltage. If you get battery voltage at that same terminal when it's disconnected from the resistor, then the rest of the wiring is fine. You can confirm by connecting that terminal straight to the jump post to see what happens to the voltage. If no change, the problem is probably the resistors and/or coil(assuming your meter is accurate). If you get closer to 10-10.5 V, then there is a problem with a connection upstream of that point.
I would add a wire as a last resort. Chances are your wiring is fine and it's a connector or the ignition switch that's acting up.
I could lend you a working coil to test with, but it's not a good replacement -- it's leaking. Better to throw borrowed or used parts at it while troubleshooting, then buy new when you're sure what needs replacing.
I would add a wire as a last resort. Chances are your wiring is fine and it's a connector or the ignition switch that's acting up.
I could lend you a working coil to test with, but it's not a good replacement -- it's leaking. Better to throw borrowed or used parts at it while troubleshooting, then buy new when you're sure what needs replacing.
Since the resistors and coil all measure out of range( remeasured new and old meter battery same resistances), I think I'm going to replace both resistors and the coil.
Looking at the wiring diagram with my resistors giving 0.6 and 0.8 respectively, my coil sees a total resistance of 0.8 Ohms during cranking which fires the plugs, but 1.4 Ohms during "running", which drops the coil term 15 to 0.9V and prevents running.
BTW I tried a 3-way jumper for the AFC relay and got my old result of firing when cranking only. I think that means my relay is OK but I was not jumping it properly. Thanks Chris (and Jack).
03-07-2009, 01:29 PM
#26
Rennlist Member
Good call on the resistors and coil. The fact that you see a higher output voltage with a direct connection implies that there is a high-resistance connection upstream, either at the switch or the panel. This may be heat-induced from the high resistance at the resistors. Check for 10 - 10.5v at the ssame point once you have it together with new parts.
03-07-2009, 01:52 PM
#27
Rennlist Member
Thread Starter
More data:
I eliminated the 0.6 Ohm resistor leaving my 0.4 Ohm in place for the starter circuit, but went direct to the coil 15 terminal with a jumper cable from the resistor input wire. This provided 8.5V to the coil in the run position (and during starting).
Well the car STARTED AND RAN FINE. I shut it down after 10 seconds, but I definitely think we are on the right track. I should get my new resistors and coil next Thursday, so maybe I'll be back on the road by next weekend.
Thanks for the help.
I eliminated the 0.6 Ohm resistor leaving my 0.4 Ohm in place for the starter circuit, but went direct to the coil 15 terminal with a jumper cable from the resistor input wire. This provided 8.5V to the coil in the run position (and during starting).
Well the car STARTED AND RAN FINE. I shut it down after 10 seconds, but I definitely think we are on the right track. I should get my new resistors and coil next Thursday, so maybe I'll be back on the road by next weekend.
Thanks for the help.
03-07-2009, 09:45 PM
#29
Rennlist Member
Thread Starter
Because Sharkskin, the guy who wrote the book on CE panel rehab, said I might have some upstream high resistance: I pulled the Ce panel. I found one burned wire leading to the X bus. The 15 circuit was all low resistance. The ignition switch was also low resistanceA1 to A5 w/switch turned to Run. . A5 to O5 low resistance in CE panel. For now I think I have eliminated all but the harness from CE panel to ballast resistor.
I think I am convinced that ShSk was right and the new parts should put me in good shape. Thanks a lot to all.
I think I am convinced that ShSk was right and the new parts should put me in good shape. Thanks a lot to all.
