motor wont start, where shud I start?

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screeminDemon

screeminDemon

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the 360 I built last year has been starting and running like a champ, until just a few days ago... Now it wont start, intermittently, until it decides it wants to. It turns over and over but sounds like not getting any spark.

Note: it seems if I turn the key off then back on a couple times it suddenly gets juiced and fires right up. The ignition switch in my 71 demon died long time ago and I rigged up a toggle/rocker switch to actually start my car after I turn the key to ON position.

My motor is mostly stock with a few upgrades... cam, carb and intake. I put electronic ignition on it when I rebuilt it last year and it has the famous "orange box"

I dont know where to start troubleshooting this. Can someone tell me the first few things I should check? Thanks!
 
i would first try re-grounding the ECU to the body. i would second try a different ECU to see if it fires.
 
screeminDemon said:
the 360 I built last year has been starting and running like a champ, until just a few days ago... Now it wont start, intermittently, until it decides it wants to. It turns over and over but sounds like not getting any spark.

Note: it seems if I turn the key off then back on a couple times it suddenly gets juiced and fires right up. The ignition switch in my 71 demon died long time ago and I rigged up a toggle/rocker switch to actually start my car after I turn the key to ON position.

My motor is mostly stock with a few upgrades... cam, carb and intake. I put electronic ignition on it when I rebuilt it last year and it has the famous "orange box"

I dont know where to start troubleshooting this. Can someone tell me the first few things I should check? Thanks!
Click to expand...
So it is getting spark cause it starts after fiddling with the key ? Sounds like a new ignition switch might help . Check wires to coil , make sure ECU is well grounded to body .
 
It does sound like an ignition switch. Do yourself a favor and find a NOS switch. The aftermarket ones I have found are usually imported from Asia.
 
73AbodEE said:
i would first try re-grounding the ECU to the body. i would second try a different ECU to see if it fires.
Click to expand...

Thanks. I will check the grounding of my orange box. When I put it on last year I sanded the paint off the rear firewall and screwed it directly onto the bare metal. But maybe it has loosened or something...

Also - I do have a spare ECU (regular old metal/chrome box) that I can try.
 
screeminDemon said:
Thanks. I will check the grounding of my orange box. When I put it on last year I sanded the paint off the rear firewall and screwed it directly onto the bare metal. But maybe it has loosened or something...

Also - I do have a spare ECU (regular old metal/chrome box) that I can try.
Click to expand...

i recently had the same problem develop. i would turn the key and it would not fire until the key was on its way back to the start position. i would crank it a few times , then it would start. i was thinking it was a fuel problem. it gradually got worse until it would not start at all. i pulled the ECU box off, stuck a new one on there, it fired and ran immediately. then a couple days later, it happened again. im thinking WTH? i pulled the ECU off, took a flap disc to the box mounting tabs and the fender apron where the ECU mounts and sanded all the surfaces to bare metal. i re-mounted the box, it has been working flawlessly for 2 weeks now.

it was a combination of the ECU going bad coupled with a bad ground
 
AHamilton said:
It does sound like an ignition switch. Do yourself a favor and find a NOS switch. The aftermarket ones I have found are usually imported from Asia.
Click to expand...

Yes the ignition switch concerns me... ever since it stopped turning over the engine several years ago and then I bypassed it. But I still need to turn the key to the on position before hitting my bypass rocker switch to start the engine.

But it seemed like a really difficult intricate job to swap out the ignition switch (hence the reason I just bypassed it when it failed originally). Is there a way I can bypass it totally... eliminating the need for a key to start it?
 
I think that when it doesn't start you should chk it for spark.
It probably doesn't, but just to be sure what you are dealing with.
 
screeminDemon said:
Yes the ignition switch concerns me... ever since it stopped turning over the engine several years ago and then I bypassed it. But I still need to turn the key to the on position before hitting my bypass rocker switch to start the engine.

But it seemed like a really difficult intricate job to swap out the ignition switch (hence the reason I just bypassed it when it failed originally). Is there a way I can bypass it totally... eliminating the need for a key to start it?
Click to expand...

if you had to install a seperate start button thingy, try unplugging the NSS at the firewall and put jumper wire across it. chances are good the NSS is bad, the starter relay is bad, or the shifter linkage needs adjusting. have you tried putting it in neutral and starting it with the key?
 
Does your 71 have the ignition switch in the column or on the dash? If the later, it is simple to swap (especially w/ special collar nut tool) and a new switch is $11. If former, you can find detailed instructions w/ photos on FABO. Saw them a few months ago.
 
BillGrissom said:
Does your 71 have the ignition switch in the column or on the dash? If the later, it is simple to swap (especially w/ special collar nut tool) and a new switch is $11. If former, you can find detailed instructions w/ photos on FABO. Saw them a few months ago.
Click to expand...
?
I thought 70 up were all on the column ?
 
73AbodEE said:
i recently had the same problem develop. i would turn the key and it would not fire until the key was on its way back to the start position. i would crank it a few times , then it would start. i was thinking it was a fuel problem. it gradually got worse until it would not start at all. i pulled the ECU box off, stuck a new one on there, it fired and ran immediately. then a couple days later, it happened again. im thinking WTH? i pulled the ECU off, took a flap disc to the box mounting tabs and the fender apron where the ECU mounts and sanded all the surfaces to bare metal. i re-mounted the box, it has been working flawlessly for 2 weeks now.

it was a combination of the ECU going bad coupled with a bad ground
Click to expand...

Excellent! that sounds exactly like what I'm dealing with... I noticed a couple times that it seemed to fire when I was giving up and turning the key back to OFF position. Thanks for your input!
 
73AbodEE said:
if you had to install a seperate start button thingy, try unplugging the NSS at the firewall and put jumper wire across it. chances are good the NSS is bad, the starter relay is bad, or the shifter linkage needs adjusting. have you tried putting it in neutral and starting it with the key?
Click to expand...

Thanks for your input. My car is a 4 speed so I dont have to worry about shifter linkage or neutral switch. But yes - I was wondering if I should check the starter relay or solenoid or something like that...
 
BillGrissom said:
Does your 71 have the ignition switch in the column or on the dash? If the later, it is simple to swap (especially w/ special collar nut tool) and a new switch is $11. If former, you can find detailed instructions w/ photos on FABO. Saw them a few months ago.
Click to expand...

Column. So not easy to swap out. I may check out the detailed instructions you mention, especially if there is photos. Thats what i would need. Lets face it - I really need to change out that switch anyways. I've got half the **** on this car MacGuyverd... but my jerry rig stuff usually works pretty good
 
TrailBeast said:
I think that when it doesn't start you should chk it for spark.
It probably doesn't, but just to be sure what you are dealing with.
Click to expand...

thanks for your input. I'm positv that when it not starting, it not getting spark. I know the sound of my engine really well... and when it gets any spark at all it fires up instantly
 
Yea column ignitions aren't the funnest to swap. I am not the best when it comes to electrical issues, but I always go back to the basics...If it starts when cold but not hot it is an electrical resistance issue, make sure all connections are clean and use a test light to see is power is getting to that point. Outside of that...your on your own pal. Hey this might be a good reason to go out and buy a new tool, YEA!!!
 
You can access the column connector under the column, pull the little trim off. You can backprobe the connector with a light or meter and see where you are at.

Colors are all pretty standard

Big red -- battery coming to switch

Big black -- switched ACC power to fuse buss

Dark blue --ignition run, or IGN 1

Brown resistor bypass, or IGN 2

yellow start which fires start relay
 
A basic test lamp wont be adequate in this case. There is enough current to enegize and run the starter. We know that much. We dont know we have adequate voltage on the brown ign.2 or blue ign.1 without a volt meter.
Just the addition of an electric choke can rob the voltage needed if the voltage was already border line low.
I would replace an ignition switch that is already known bad, then see if another problem exists.
 
Didnt read all of the posts, just because im tired, but on my SuperBee (383), It does this every once in a while. For me, my problem is just a bad connection at the switch.. If i press on the wires going into the key switch, it fires right up.
 
Check the ignition switch for sure, I don't if already stated but check the ballast on the ignition, mine went bad and cause the alternator to stop charging the battery. I'd crank the thing over and over but wouldn't start, seemed like no spark at the time. I'd get it to start and then it would do it again a few days later haha.
 
RedFish said:
A basic test lamp wont be adequate in this case. There is enough current to enegize and run the starter. We know that much. We dont know we have adequate voltage on the brown ign.2 or blue ign.1 without a volt meter.
Just the addition of an electric choke can rob the voltage needed if the voltage was already border line low.
I would replace an ignition switch that is already known bad, then see if another problem exists.
Click to expand...


Great input. You're right, I need to replace the bloody switch and stop whining about it. I think thats the most logical starting place. Last night I checked a few things and I believe my orange box is grounded nicely still.
 
67Dart273 said:
You can access the column connector under the column, pull the little trim off. You can backprobe the connector with a light or meter and see where you are at.

Colors are all pretty standard

Big red -- battery coming to switch

Big black -- switched ACC power to fuse buss

Dark blue --ignition run, or IGN 1

Brown resistor bypass, or IGN 2

yellow start which fires start relay
Click to expand...

Excellent! I've printed this out to help with my troubleshooting. I love this website. Thanks again!
 
67 273 said:
Didnt read all of the posts, just because im tired, but on my SuperBee (383), It does this every once in a while. For me, my problem is just a bad connection at the switch.. If i press on the wires going into the key switch, it fires right up.
Click to expand...

YOur another one that has convinced me to go after the ignition switch first, thanks for your input!
 
7dswinger said:
Check the ignition switch for sure, I don't if already stated but check the ballast on the ignition, mine went bad and cause the alternator to stop charging the battery. I'd crank the thing over and over but wouldn't start, seemed like no spark at the time. I'd get it to start and then it would do it again a few days later haha.
Click to expand...

Ignition is where I'm attacking first. Your right - the resister could be a culprit too, I've noticed that little bastard gets really hot. I value your input, thank-you!
 
put the key in on position and jump the solonoid relay...if it starts, your toggle is junk
 
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