Start up problems, 72-LS5
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Start up problems, 72-LS5
We've had some problems with our 72' 454 and I am not sure what to try next. It will start cold fine, but once it warms up, it doesn't like to restart sometimes. The problem doesn't happen every time on the restart.
Initially, we thought it was the starter. We have replaced it, and swapped the replacement a couple of times after the hot restart issued continued.
Then we went ahead and replaced the entire engine wiring harness. It had been spliced and cut on in the past, so we went and replaced it. Still, the problem is there.
Now, I am not sure what to try. I've had someone tell me to replace the ignition switch, and also to try and replace the ignition coil.
What would you suggest?
Initially, we thought it was the starter. We have replaced it, and swapped the replacement a couple of times after the hot restart issued continued.
Then we went ahead and replaced the entire engine wiring harness. It had been spliced and cut on in the past, so we went and replaced it. Still, the problem is there.
Now, I am not sure what to try. I've had someone tell me to replace the ignition switch, and also to try and replace the ignition coil.
What would you suggest?
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Based upon only this:
It could be anything.
How, in unambiguous terms, does it not like to restart when hot? Cranks slow, not at all, cranks fine but won't fire....
it doesn't like to restart sometimes
How, in unambiguous terms, does it not like to restart when hot? Cranks slow, not at all, cranks fine but won't fire....
Drifting
Joined: Aug 2003
Posts: 1,327
Likes: 16
From: Fl
Disconnect every ground cable on the car. Clean and rough all the surfaces. The battery cable ground to the frame, clean the frame too.
The ground cable from the engine bloack to the frame, by the starter, clean the frame area very well.
I had the same problem, and I cleaned all gounds. The problem went away for me.
Also - inspect the groud cables, straps to be sure they are still capable of providing a good ground and replace if necessary.
Bill
The ground cable from the engine bloack to the frame, by the starter, clean the frame area very well.
I had the same problem, and I cleaned all gounds. The problem went away for me.
Also - inspect the groud cables, straps to be sure they are still capable of providing a good ground and replace if necessary.
Bill
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Originally Posted by Easy Mike
Sounds like heat soak. Check to ensure all the appropriate heat shielding is protecting the starter.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Originally Posted by gerry72
Based upon only this:
It could be anything.
How, in unambiguous terms, does it not like to restart when hot? Cranks slow, not at all, cranks fine but won't fire....
It could be anything.
How, in unambiguous terms, does it not like to restart when hot? Cranks slow, not at all, cranks fine but won't fire....
The starter isn't real sluggish or cranking slow when this happens.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
67L36 and 72ls5fla, thanks for that feedback. I had started thinking about just ordering a new repro coil and trying that. The grounds also make great sense. I may try those two items and see if the issue goes away.
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Drifting
Joined: Feb 2005
Posts: 1,438
Likes: 2
From: Melrose Florida
Since you get nothing (no cranking) it must be either grounds or the ignition switch.
Changing the coil won't have any effect. Do your dash lights, interior lights, horn, headlights work during the "dead" period?
I'm thinking ignition switch -- they do go bad.
Changing the coil won't have any effect. Do your dash lights, interior lights, horn, headlights work during the "dead" period?
I'm thinking ignition switch -- they do go bad.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Originally Posted by halfmoontrail
Since you get nothing (no cranking) it must be either grounds or the ignition switch.
Changing the coil won't have any effect. Do your dash lights, interior lights, horn, headlights work during the "dead" period?
I'm thinking ignition switch -- they do go bad.
Changing the coil won't have any effect. Do your dash lights, interior lights, horn, headlights work during the "dead" period?
I'm thinking ignition switch -- they do go bad.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Originally Posted by Harps
Yes, they all seem to work during the dead periods. Does that sound like an ingnition switch then?
The switch could also be out of adjustment. Turning the key simply moves a rod up and down the column that moves the internal slide of the switch to the different positions. By loosening the screws that hold it to the column you can adjust the switch up and down so that the key position corresponds exactly to the switch position.
Good luck... GUSTO
Advanced
Joined: Sep 2005
Posts: 93
Likes: 0
On my 73 454 I used to have similar problems. It would start when cold and such, but after it was hot it would some times take a couple trys or a little more kick like a jump. After I did some engine mods like heads and cam I bumped my compresion up to around 10.3 this compounded my problems. The guys at the shop said the big blocks are just harder to turn over and if you up the compresion its even worse. I installed one of those gear reduction starters from ecklers and it totally solved my problems. Starts any time any temp. When the engine is cold the compresion has bled off and it will crank easier. When its hot the compresion on my car seemed higher and harder to crank. I cant say enough good about the gear reduction starter, its a smaller motor, lower amp draw, easier on the battery and cables/wiring. Before I couldnt even have the door open when starting because the interior lights seemed to pull just enough amps to take away from the starter. Now it seems like I could sit and crank all day with out pulling the battery down.
Race Director
Joined: Sep 1999
Posts: 11,360
Likes: 382
From: Plano TX
Another thing it could be is the neutral safety switch. 4-speeds have it near the clutch pedal. Dunno where it is on an auto, but they have them too. If it is bad you would have exactly the same symptoms as the bad ignition switch. To check, pull the connector off the switch and temporarily jumper it with a wire atleast as big as the wires going to the switch.
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Originally Posted by kb2fzq
Nobody has mentioned if it's auto or 4 speed...I'd lean towards neutral safety switch, if auto, I'd at least address it..
Thread Starter
Le Mans Master
Joined: Apr 1999
Posts: 8,638
Likes: 151
From: Raleigh NC
Gusto, and everyone else, thanks for the feedback on this.
I've never replaced, or worked on the ignition switch. Is it safe to assume the steering wheel has to come off to get access to it?
I've never replaced, or worked on the ignition switch. Is it safe to assume the steering wheel has to come off to get access to it?
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Not at all... It's attached to the top of the column about where your feet are and you will see a flat plug about 2" long that snaps into it.
It is helpful to lower the column by loosening the two bolts that attach it to the dash (beneath the trim piece held on by two screws), and the bolts at the base of the column that go through the firewall. This will drop the column a few inches and make it easier to reach the switch. You can also reach up on top of the column and feel the rod that goes to the switch as well as the switch itself first and see if anything is loose. You may even be able to move the rod a few milimeters to see if that does work.
Having said that, and in light of the fact that you have an automatic, I do think I would check out the safety neutral switch. Sometimes when it's bad and won't start, you can move the shift lever back and forth to get it to work, as well as try neutral. If you do find this works, I would zero in on that switch as the problem.
Good luck... GUSTO
It is helpful to lower the column by loosening the two bolts that attach it to the dash (beneath the trim piece held on by two screws), and the bolts at the base of the column that go through the firewall. This will drop the column a few inches and make it easier to reach the switch. You can also reach up on top of the column and feel the rod that goes to the switch as well as the switch itself first and see if anything is loose. You may even be able to move the rod a few milimeters to see if that does work.
Having said that, and in light of the fact that you have an automatic, I do think I would check out the safety neutral switch. Sometimes when it's bad and won't start, you can move the shift lever back and forth to get it to work, as well as try neutral. If you do find this works, I would zero in on that switch as the problem.
Good luck... GUSTO
Last edited by GUSTO14; Dec 16, 2005 at 10:41 AM.
Burning Brakes
Joined: Aug 2005
Posts: 1,126
Likes: 0
From: Hudson Falls, N.Y. 76 Vette Modified L-48
Try this...next time it acts up, turn the key and hold it in full ingition position with your left hand and shift the lever forward then back to neutral and all thru the gears (with your foot on the brake hard)...if the engine turns over or grunts in any gear....it's the neutral switch...try that...my auto does that every once in a while...I push it full forward into park and VROOOM...
CF Veteran
Joined: Aug 2005
Posts: 1,429
Likes: 19
From: Northern CA
St. Jude Donor '10-'12, '25
Have you verified the capacity of the battery? Check the voltage of the battery with the car off, during cranking, and once started... Batteries act up when going bad. 
