69 L71 will not fire off

[Lawrence S.]

Re: 69 L71 will not fire off

Rich,

See my reply below:

Background.....The PU coil generates a very small pulsed DC voltage to trigger the TI Amp module at each rotation of the 8 distributor poles/plug wire positions. The voltage is around 2 volts. It is VERY important that the polarity of the 2 distributor PU coil lead wires to the harness is correct. Since you've had to replace some wires, it is possible someone else before you had the connectors apart, and reversed them, or maybe you did accidentally. I CHECKED POLARITY AND IT IS CORRECT. I EVEN SWITCHED THEM NO SPARK. I SWITCHED BACK TO CORRECT POLARITY.

Additionally, certain TI module circuit board designs may be more sensitive to these low input voltages. It has not been determined which of the 3 types of boards are in your system, original Delco, M&H reproduction, or K&B reproduction. You would have to open the AMP Module case to verify. Internal module grounds to the circuit board of course are important as well. You may have to open it up to verify at some point. I HAVE NOT OPENED UP THE AMP YET.

I would check the following:

The PU coil WHITE wire connects to the harness PINK wire. This is the source power to both the PU coil AND the TI Module.
The PU coil WHITE/GREEN (or if PU was OTC replaced, the GREEN wire) connects to the harness GRAY wire. This is the PU coil output wire which is the trigger wire to the TI Amp.

If these 2 wires are reversed, it can cause intermittent/weak trigger pulses to the Amp. You may have to remove the dist cap and carefully trace the wire colors inside at the PU coil wire pair down to your repaired external connector OOPS FORGOT TO DO THIS.

If those appear correct......

At crank, the PU coil pulses are of short duration, therefore a higher voltage is required at crank as the battery supply is being reduced by the starter motor current draw. This much like a Ballast resistor bypass in a points ignition system at crank. The harness includes a small gauge PINK wire which directs full battery voltage to power the AMP AND PU coil input. This higher voltage is needed to ensure proper supply voltage at crank.

The PINK wire source is the Starter Solenoid "R" terminal. In the engine/forward harness, there is a single plastic plug wire terminal from the solenoid R which connect to the associated TI Harness plug, likely running along the upper hood ledge area. Visually check that is there and verify proper voltage at crank, below. FOUND THIS PLUG AND IT IS SNUG

Connect your - meter lead to ground, + meter lead to the distributor PU coil WHITE/ TI Harness PINK wire. Turn IGN ON, no crank. You will see a reduced battery voltage on the meter as there is a resistor wire in the harness to drop voltage to the AMP. Record voltage reading. 7.68 VOLTS WITH IGNITION ON AND NO CRANK.

Then while observing the meter, crank the engine and record voltage. It should be higher than previous reading, at or near full battery voltage during crank. As a reference, you can record the battery voltage at the +cable during crank also. DURING CRANK THE VOLTAGE DROPS TO 3.9 VOLTS. BATTERY VOLTAGE IS 12.13

SINCE THE VOLTAGE DURING CRANK IS VERY LOW WHERE SHOULD I FOCUS MY ATTENTION?

Thanks very much,

Lawrence

There of course are other possibilities causing your weak spark. These are just a few to try, but should be verified to help diagnose the fault.

[Richard M.]

Re: 69 L71 will not fire off

Lawrence, You've made good progress. 7.6v with IGN ON is a indication a high resistance through the coil or a poor ground somewhere. You added a ground to the coil-, BUT, it may not be getting to the TI module. Check that using a ohmmeter, between a good engine ground and the TI module case(not just the mount bolt or terminal). Check it at the case metal itself, even if you have to scrape a bit of the paint off.

3.9V at the R terminal PINK at crank is a failure. This could explain intermittent spark as the PU coil and TI Module are voltage deficient.

Check the PINK wire harness connection at the starter solenoid R terminal, the outer most small post on the solenoid. You may have a corroded terminal and/or solenoid stud, or possibly a bad solenoid, or a corroded harness wire.

Attach you meter directly to the stud, crank the starter and record that reading. Then pull the plug up by the hood ledge and check there also. Record that reading. If you see a different voltage, the TI harness may have a internal short.

These improper readings you're getting are really indicative of a bad ground to me.

If not, you may have to remove all TI harness plugs and connections and the check it for shorts using the ohmmeter function of your meter. If I recall from your other threads, and your explanation of the old and tattered wiring, you may be best to consider all new wiring in this car, regardless of your findings.

Rich
PS - I'm traveling back home from my vacation for the next few days but will check in when I can in the evenings. I'm sure others can help you too if I can't reply. Good luck. You're getting closer.

[Lawrence S.]

Re: 69 L71 will not fire off

Rich thanks so much. This is very helpful!

One thing I wanted to mention. The wires coming out of the distributor have the smallest conductor strands? Is this a 22 gauge wire? I have them spliced to wire and connectors I harvested from my old 67 harness, 20 gauge. I did my best to make these connections as solid as possinle. Could not solder together because no room to work.😞 Is this a potential problem since this is not soldered?

When I got the car there were several bad connections that just needed a good cleaning. Had decent success so far with good clean up. However this harness has had its fair share of cuts and splices😁. A replacement is probably a good idea. But will try to fix this in the meantime.
Thanks again Rich.

Lawrence

[Richard M.]

Re: 69 L71 will not fire off

Rich thanks so much. This is very helpful!

One thing I wanted to mention. The wires coming out of the distributor have the smallest conductor strands? Is this a 22 gauge wire? I have them spliced to wire and connectors I harvested from my old 67 harness, 20 gauge. I did my best to make these connections as solid as possinle. Could not solder together because no room to work. Is this a potential problem since this is not soldered?

When I got the car there were several bad connections that just needed a good cleaning. Had decent success so far with good clean up. However this harness has had its fair share of cuts and splices. A replacement is probably a good idea. But will try to fix this in the meantime.
Thanks again Rich.

Lawrence

Lawrence, After splicing the wires, did you do the distributor PU coil ohms test(500-700 ohms) and when testing did you simulate movement and vibration by wiggling the connector/wire assembly with meter attached? This will verify integrity of the repair.

The wire gauge you used should be fine. However, if you want the best overall connection in your repair, I'd have removed the distributor and the pickup coil and solder spliced and heat shrunk it above the distributor base/wire grommet area to prevent future connection failure.

There is nothing wrong with doing wire repairs as long as it equals or surpasses the original design. I wouldn't really trust a butt-spliced connection under the distributor. Chances are it could fail at a inopportune time.

Rich

[Lawrence S.]

Re: 69 L71 will not fire off

Lawrence, After splicing the wires, did you do the distributor PU coil ohms test(500-700 ohms) and when testing did you simulate movement and vibration by wiggling the connector/wire assembly with meter attached? This will verify integrity of the repair. I DID NOT. THAT NEEDS TO BE MY NEXT STEP.

The wire gauge you used should be fine. However, if you want the best overall connection in your repair, I'd have removed the distributor and the pickup coil and solder spliced and heat shrunk it above the distributor base/wire grommet area to prevent future connection failure. I AGREE. I WANT TO GET THE CAR RUNNING AND MOVE TO ANOTHER SHOP. I NEED THE SPACE THAT THIS CAR IS OCCUPYING FOR MY 69 Z28ONCE MOVED I WAS GOING TO PULL THE DISTRIBUTOR AND FIX FOR LONGEVITY.

There is nothing wrong with doing wire repairs as long as it equals or surpasses the original design. I wouldn't really trust a butt-spliced connection under the distributor. Chances are it could fail at a inopportune time. I AGREE WILL LET YOU ALL KNOW WHAT I FIND.

[Lawrence S.]

Re: 69 L71 will not fire off

The pick up coil resistance is .583 ohms with my meter set at 2K ohms. I checked this under the wiggle test, with my mighty vac and also static. Had the same results. This must be a failure unless the reading should be between .500 - .700 ohms or my meter is off? My meter is an old Fluke digital that I used 30 years ago in the Coast Guard.
I retested the spark using my timing light and now I get a constant pulse from the light. Apparently when I repaired the distributor wires paying closer attention this time I made a better connection.
I reconfirmed the ground to the radiator support and to the TI amp. It is all good there.
I need to put the car on the lift and check the R wire connection on the solenoid. I expect there is a problem there.
Lawrence

[Richard M.]

Re: 69 L71 will not fire off

The pick up coil resistance is .583 ohms with my meter set at 2K ohms. I checked this under the wiggle test, with my mighty vac and also static. Had the same results. This must be a failure unless the reading should be between .500 - .700 ohms or my meter is off? My meter is an old Fluke digital that I used 30 years ago in the Coast Guard.
I retested the spark using my timing light and now I get a constant pulse from the light. Apparently when I repaired the distributor wires paying closer attention this time I made a better connection.
I reconfirmed the ground to the radiator support and to the TI amp. It is all good there.
I need to put the car on the lift and check the R wire connection on the solenoid. I expect there is a problem there.
Lawrence

Lawrence, Your Fluke is likely auto ranging and readings can be deceiving. .583 ohms is nearly a dead short and I doubt that's the actual. More like 583 ohms which is typical. Verify with another meter to be sure, but if you're seeing "some spark" via timing light pulses then the PU is functional. However, it may be a weak spark and not strong enough to fire off the engine.

Got fuel?

Rich

[Lawrence S.]

Re: 69 L71 will not fire off

I have plenty of fuel. Can see it and smell it. I don't think my spark is strong enough to "light the fire". Remember my voltage at the TI plug was 3.9 volts not nearly 12 when cranking. I am going to look the red wire at the R terminal on the solenoid and see if I can improve that connection and also follow that wire. I have the car up on my lift now. The harness is a mess. I am going to buy a new harness and install that.
Keep you posted, and thinks for the help thus far.
Lawrence

[Lawrence S.]

Re: 69 L71 will not fire off

Rich,
Installed a new wiring harness and got the car started. The harness I removed was hacked on, added to was basically a mess. However, when I started the car it had a miss. When I had repaired the distributor wires I had to remove the cap resulting in spark plug wires coming off. I thought I put them back in the right place but apparently not. Now when I start the car i get a aggressive pop through the carb. I am going to pull the cap and index number 1 with the "0" on the timing tab and go from there. Eventually I need to pull the distributor and solder those wires correctly.
Thanks for all of you help. I really appreciate it.
Lawrence

[Lawrence S.]

Re: 69 L71 will not fire off

Guys,

Reviving this old thread since I have the car running now. I still need to check for a corroded solenoid stud or bad solenoid because of the low voltage coming from the pink wire. Will report back once I have it on the lift. Meanwhile I am driving the car but it still needs some sorting.

Lawrence

[Lawrence S.]

Re: 69 L71 will not fire off

I had a bad solenoid on the starter which I thought was the source of this issue. When I put the fresh starter solenoid on the car ran great...started normal. Then today back to the same old problem. I switched out the solenoid thinking it went bad, but that was not the problem. Next move is to install a new pickup coil that I have. I don't know how to install that so will be posting tons of questions...I am sure. Once I have the distributor out will be back on the board.

Thanks for all the help.
Lawrence

[Duke W.]

Re: 69 L71 will not fire off

Disassembling a TI distributor is not much different than a single point. It's simple and the procedure is in your COM. You also have the opportunity to shim up the end play to the two to seven thou spec and grease the upper bushing grease well. (I suggest Mobil 1 synthetic grease.)

Make sure you reinstall the gear with the dimple pointing the same direction as the rotor tip, which is how it should be currently oriented, but verify before you knock out the roll pin. A quarter-inch punch is what you need to remove/install the roll pin. If the shaft has essentially zero to barely perceptible side play, the bushings are okay.

Don't put any grease or oil on the centrifugal mechanism. Just clean everything thoroughly and wipe down the parts with WD-40, which will provide corrosion protection.

Duke

[Richard M.]

Re: 69 L71 will not fire off

Duke has explained well, However..........

If you are using the reproduction TI coil and magnet assembly you may have some trouble aligning the tips of the rotating pole piece to maintain proper clearance to the stationary tips of the assembly. You should be able to get aproximately the thickness of a business card sliver between each one when rotating the shaft/pole piece. Check all 8. If necessary loosen and t w e a k the 3 magnet attaching screws for proper alignment.

Before you take it apart do a test to see what the existing clearance is. Remove the stator from the magnet and match it up to the new stator to see if it's a accurate match. If it is, reassemble and test clearance again. If you are not comfortable with clearance you can use the original stator.

Assist photo....


Misc reference photos of what it'll look like when you take it out.

[Lawrence S.]

Re: 69 L71 will not fire off

Thanks Rich, plan to work on it next week.

Lawrence

[Lawrence S.]

Re: 69 L71 will not fire off

Thanks to Duke and Rich. I rebuilt the distributor and the car now runs better than it has ever run. Rich the pictures helped out a lot and the tip about the rotating tooth being the thickness of a business card from the stator helped out a lot. Sure enough when I put the distributor back together the new stator was barely hitting the rotating teeth so I used the original one and then made very slight adjustments and all fit well. Actually I think that I may had been able to make those same slight adjustments with the new stator and perhaps it would had aligned properly too. You live and learn as you go along. It really was not difficult to do this work. Just had to pay attention as you went along. The drive gear was installed correctly, but the end play was way out of spec. So I was able to shim this up and put it back to spec. I used Mobil 1 synthetic grease to grease up the upper housing and below the felt. Cleaned everything else up. I still need to map the distributor. I believe the old stiff springs are still on the distributor. I will get to that next phase. It was just nice to have the car start properly and idle so nice. I look forward to putting miles on the L71.
Thanks again!
Lawrence