Runs Fine And Now Won't Start - What Did I Do???

[Don L.]

What a day. I was able to get a nice used temp sender for my '72 L48 and got it installed and reading well yesterday. I'll finish that thread up soon.

Now my next problem/challenge - all of a sudden, after test driving it to confirm temp sender is working and accurate, the car won't start.

Here's what I have:
I turn the key and I get one click, then nothing. Courtesy lights go out, key buzzer quits, nothing electrical works. I wiggle and re-tighten the battery connections. Same thing, over and over. It'll click once then dead, until I repeat the wiggle/tighten process and try again.

I remove the battery and run jumper cables from the battery to the positive and negative cables in the car. I get the "rattling" noise like any time a battery is weak. (Battery is new and tests 12+ volts). It does this each time I turn the key.

I check the (-) connection to the frame. Good. I check the (+) connection to the starter solenoid. Good.

I tapped on the solenoid and the starter case with a small hammer, in case one of them was in a dead spot (?). Fail.

I hook up a fully charged booster instead of battery. Turn the key. Same rattling noise but no start.

Bumped the car in 3rd gear to move the flywheel in case bendix is stuck in the flywheel. Nope - same as before.

Very frustrating. Any ideas appreciated. Please!

Thanks

[John P.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hello Don, It definitely sounds like a connection problem. One of the most overlooked connection problems on a side terminal battery is the cable bolt contacts. Remove both battery cable mount bolts from the cable ends by pushing them out of the cable ends. You will probably find corrosion inside the cable boot. Clean the bolts and both the inner and outer cable contact surfaces. Hope this helps, as I have seen this problem on several side terminal cables. I have had cars with new batteries installed towed into our shop only to find this connection issue. John

[Keith W.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hello Don, It definitely sounds like a connection problem. One of the most overlooked connection problems on a side terminal battery is the cable bolt contacts. Remove both battery cable mount bolts from the cable ends by pushing them out of the cable ends. You will probably find corrosion inside the cable boot. Clean the bolts and both the inner and outer cable contact surfaces. Hope this helps, as I have seen this problem on several side terminal cables. I have had cars with new batteries installed towed into our shop only to find this connection issue. John

John what do you recommend to clean the contact surfaces with?

[John P.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hello Keith, I have always used a small wire brush to clean the bolts, cables and battery terminals. Most of your more common tool suppliers sell side terminal cleaning brushes. John

[Don L.]

[David H.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Don,

Battery load test?

Dave

[Bill B.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hi Don, I'm a retired electrical engineer and if you are still experiencing issues after the cable cleaning, try the following: With a digital or analog voltmeter, find a clean spot on the engine to attach an alligator lead to the negative (-) side of the meter. With another alligator lead on the positive (+) lead of the meter, attach it to the starter solenoid's large BATT + lead terminal. Place the meter where you can observe it when you try starting the car. If it stays pretty much indicating +12 Volts during the attempt but not cranking, then it is your starter or the starter's solenoid, or the starter solenoid's circuit at fault. This exonerates the battery and the battery cable connections, both the + and the -.

If however, the meter is fluctuating wildly during the cranking attempt, then the cables, connections, or battery is the cause.

To check the starter solenoid circuit, transfer that meter's + alligator clip from the Stater solenoid's BATT + terminal to the yellow/white/red wire's small terminal on the solenoid. If pretty much steady +12V when trying to start, then the circuit to the solenoid (including the clutch safety switch and ignition switch) are now exonerated as well, thus truly pointing to the starter/solenoid assy as root cause. If fluctuating, (but the meter was indicating steady +12 during the previous test above when connected to the big BATT + terminal at the solenoid) you must troubleshoot the connections and items between the ignition switch and the starter solenoid, including that Clutch safety switch.

Let us know how you made out.

[Don L.]

[John P.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hello Don, You are going to have to check voltage at your starter connections. You may have a voltage issue to the crank terminal on the solenoid. Assuming you have good battery voltage and ground at the starter, you can jump the solenoid at the terminals and eliminate the crank circuit. If this fails to crank the engine, your problem lies in the starter and/ or solenoid. If the engine cranks when jumped at the solenoid, you will have to back trace the wire to the solenoid. You can possibly have a bad connection at the bulkhead connector, ignition switch or neutral safety switch. I know you said the battery is new and shows 12+ volts, however I would still run a cold crank test to see what the amp output of the battery is. Also check the ground to the engine ( a jumper cable can be used as a temporary ground for testing) Have a helper hold the key in the crank position and twist or tug on the battery connections and wire connections at the bulkhead and engine harness connectors. You will probably find the faulty connection by trying this. John

[Don L.]

[Don L.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hi all. Circling back on this thread, I wanted to update the group on where I sit today.

I took the advice of several posts and tested the battery, the cables, the starter and the solenoid. I did see a 9 volt drop in voltage when the key was turned. I also pulled the starter and found it was "hammering" instead of extending and spinning as it should when tested on the bench. I sent the starter and (original) solenoid out for rebuild. The rebuilder told me he found tired brushes and other components in the starter and the solenoid. When I re-installed the rebuilt components, I still had the problem of too little voltage getting to the starter to make it spin up. When I turned the key, I'd get a "click", then all the lights, key buzzer and everything else would go out. Similarly, I discovered that if I disconnect the ground connection on the battery and re-connect, the key buzzer restarts and the courtesy lights come on. This lasts until I turn the key again and then everything goes out again. Rinse/repeat ad ad nauseam.

Thinking about the tips I received here, I took all the primary and secondary connections apart, cleaned them up and reconnected them. This included the horn relay. They all looked clean but I cleaned them anyway. The car started! I let the car sit for a few days and got back to it yesterday. Same story as before - all goes out when key is turned to START. I zeroed in on the horn relay as my suspicion took me there. It cleaned and reset the ring terminals on the horn relay and voila! Ignition!

Not being sure I have identified the root cause, I wanted to ask if it makes sense to this group that my problem could be a temperamental horn relay. Could a failed relay cause the 12 volt supply to require a "re-set" by disconnecting/reconnecting power to it?

Advice appreciated.

Thanks

[Bill B.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Hi Don,

There is the possibility that one of the two fusible links that connect to the horn relay may be intermittent (internal weak spot) rather than a bad relay. There was a very good article in the latest issue of The Corvette Restorer regarding fusible links on page 36. If the links are indeed good, then the relay itself may have an issue, but I'm more inclined to think fusible links as the issue, especially at the slice points (the cylindrical black rubber molded connection) of possible corrosion as root cause.

[Don L.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Thanks Bill. Do you think that either a fusible link (I think there are two of them @ the relay) and/or the relay itself would cause all electric to go out then restore when battery is disconnected then re-connected?

[Bill B.]

Re: Runs Fine And Now Won't Start - What Did I Do???

Yes, but I believe that the disconnection/reconnection of the Batt may be just letting the fusible link cool down before attempting again. I don't see anything internal to the Horn Relay that would affect the starter circuit. If you have someone to assist, you could have someone else trying to start the car while you gently wiggle the fusible link wires at the horn relay. If you observe the starter cutting in and out as you manipulate the link wires, you have found the problem. If I was down in NC, I'd drive over to your location lend you a hand but I've returned back to CT for awhile.

[Leonard M.]

Re: Runs Fine And Now Won't Start - What Did I Do???

The horn relay is a combination of the horn relay And a terminal post for the wires that you removed and cleaned. If you think that relay post is somehow shorting out, you could actually isolate the wires, from the relay post, by removing them and connecting them together with a bolt making sure they do not touch anything. At least you eliminate the relay from your problem.
The white colored relay is the original and very hard to find, The other 2 are service replacement.
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