1969 mustang won't start, and backfires

[Jake69]

Background info
I have a 1969 mustang with a 302 2v, mallory unilite mechanical advance electronic distributor, blaster 2 coil, 9mm ford racing plugwires, autolite 42c spark plugs, stock exhaust.

What's happening
When I turn the key to the crank position, the car sounds perfectly fine, as if it should start, but never does. When I let off of the key and it falls back into the on position, the car stops cranking, and nothing else happens. Now the interesting thing is when I turn the key from the ON to the OFF position, when the car is NOT running, I experience a backfire that can be heard over a mile. The amount of time I wait before turning the key from the on to the off position after cranking doesn't seem to affect the severity of the backfire. Just to make sure I'm as clear as I can be, the car does not do anything unusual (other than not starting) until the key is returned to the off position. The instant the key returns to the off position, it backfires.

If there is any more information I can give you, please let me know. Thank you very much for your help.

 

[PoppyMod]

Background info
I have a 1969 mustang with a 302 2v, mallory unilite mechanical advance electronic distributor, blaster 2 coil, 9mm ford racing plugwires, autolite 42c spark plugs, stock exhaust.

What's happening
When I turn the key to the crank position, the car sounds perfectly fine, as if it should start, but never does. When I let off of the key and it falls back into the on position, the car stops cranking, and nothing else happens. Now the interesting thing is when I turn the key from the ON to the OFF position, when the car is NOT running, I experience a backfire that can be heard over a mile. The amount of time I wait before turning the key from the on to the off position after cranking doesn't seem to affect the severity of the backfire. Just to make sure I'm as clear as I can be, the car does not do anything unusual (other than not starting) until the key is returned to the off position. The instant the key returns to the off position, it backfires.

If there is any more information I can give you, please let me know. Thank you very much for your help.

Hi,
What is the history prior to this problem? That is, was this a case of one day it's all fine, the next this occurs?

 

[Realmongo]

With the key in the ON position, do you have volatage to the coil?

 

[2+2GT]

Turn the engine to TDC. Remove the distributor cap. Observe where the rotor is pointed.

 

[Loup-garou]

Check the Unilite module in that distributor - I think there are diagnostic instructions on the Mallory / Mr. Gasket website. IIRC, the Unilite design is sensitive to stuff like voltage spikes and poor grounds.

 

[Jake69]

It could be an issue of timing or a bad ground. The problem occurred when I was replacing the ignition system. I ensured the engine was at top dead center, removed the distributor, coil, wires, and plugs, and installed a new distributor, coil, plugs, and wires. I know for a fact all of the new components are fully functional, as they have worked before. Everything has voltage when the key is on, coil, distributor, etc. The mallory distributor has a pertronix magnetic pickup, I forgot to mention that in the first post.

 

[Ogre]

Sounds like a timing issue to me. It's possible the new distributor was installed 180 degrees out. Pull the distributor, make sure your number one cylinder is on top dead center on the compression stroke and reinstall all components. Hope this helps.

 

[rbohm]

Turn the engine to TDC. Remove the distributor cap. Observe where the rotor is pointed.

Sounds like a timing issue to me. It's possible the new distributor was installed 180 degrees out. Pull the distributor, make sure your number one cylinder is on top dead center on the compression stroke and reinstall all components. Hope this helps.

we have winners here. it sounds like the timing is way off, might not be 180 out, but it is going to be far enough off to cause the issues you are having. you are going to have to make sure the number one cylinder is at TDC, and then make sure that the rotor is pointing at the right terminal, and that the cap is wired properly.

 

[Jake69]

The distributor was a tooth off, and my Pertronix magnetic pickup went bad. Problem should be fixed once I get the new one in.

 

[StangDreamin']

How about the cam timing? Has the timing set (especially the nylon dipped cam gear) ever been changed? If not, you may be a tooth or 2 or 7 off. I've seen 40-yr-old engines like this; little chunks of the nylon coating dropping out of the pan on an oil change. Can't be seen but the timing chain is all stretched out from x00,000 miles of use. Couple of "powershifts" making the RPMs bounce around wildly, and the chain starts jumping teeth.

If you can't come up with an electrical solution and the engine to your knowledge has never been open......