Electrical issue.

[Coupe66]

Hi All.
I have an issue with my 66 Mustang with 347 engine.
Recently I noticed a slight miss fire when first cruising around 2-3000rpm . Once engine warmed up it seemed to go away and ran fine even at higher revs.
Now the car will not start at all. ??
I have good spark , fuel and compression, but will not start. Distributor has not been moved from when it was running perfectly.
 I will list the things I have done to date.
- tried 3 different MSD boxes
- tried 3 different coils
- replaced msd distributor cap and rotor.
- replaced magnetic trigger in distributor
- replaced all spark plugs
- checked all msd plug leads
- checked all wiring and connections.
- done compression test and 175-180psi on all cylinders.
Note : few times when checking for spark at the distributor with an air gap from the coil lead to the distributor, the engine started and idled fine??
 ( large spark jumping across gap. )
When I reconnected the coil lead engine would not start. ?
If I check for spark at the spark plug , again has good spark. Reconnect plug lead and still no start.
Starting to run out of ideas.
Any help appreciated.
Cheers
Wes.

[unilec5544]

How old is your fuel?

[Coupe66]

Fuel pressure is good, but I didn’t even think of the possibility of bad Batch of fuel.
Will check that tomorrow for sure.
Thanks  👍

[Clubman7]

Pink wire from ignition switch has been bypassed?
Can cause spark issues as it drops voltage the coil. 
Depends how MSD box is wired in.

[Coupe66]

Thanks Clubman7
I will check that also.
 My thoughts also. It could be something to do with ignition switch.

Cheers.

[GEOFF289]

I guess its turning over on the starter OK if you've been able to test for spark. That would seem to rule out the ignition switch I think.

It can really only be spark or fuel and you seem to have ruled out spark as the issue with all the checking and component replacement you've undertaken. It would seem that it ran OK before so doubt the pink resistor wire is still in the system. In any event, in my experience of that the engine should start anyway as it gets 12 volts on cranking but won't idle.

A fuel quality issue would have to be pretty dire for it to not run at all. You say you have checked fuel pressure - at what point in the system? Have you checked for blocked fuel filters, including the little mesh screen where the fuel line enters the carby? When you operate the throttle linkage does fuel spray into the carby bowls. Is your float level properly set? A blown power valve or crap in the needle and seat can make it so rich its very hard to start it but it should still go with enough cranking and the pedal on the floor.

That's the things I can think of.

[Coupe66]

Hi Geoff,
Agree with your comments on ignition.
The fuel from the pump shooters squirt into carby no problems.
The fuel line is clean and not blocked and good fuel pressure to bowls.
Float levels are spot on.
Would have to check power valve.
Will keep you posted with further checks.
Cheers.

[pmb0186]

I would check you are getting 12v with ignition on, as the pink wire is bypassed when cranking hence spark when cranking
I would also check your distributor cap for cranks, cracks can send spark down the wrong hole.

[Coupe66]

Finally found the problem. !!
Tried a different dissy rotor and it fired up.
The only thing I hadn’t tried as mine looked like it was brand new , but must have a fault somewhere.
Tried a mates crappy old one and started first go.
I will get a new one tomorrow.
Thanks for the help guys. 👍

[GEOFF289]

Glad you got it sorted but weird that you had spark at the plug with the old distributor.