Hi all. Just bought my first classic mustang and of course i have my first problem.
The car starts and idles fine, no problems for the first 4-5 miles. After that i start to get misses, then a few minutes later it gets very close to stalling if i give it any gas at all. it seems to only be a problem after the engine has warmed up.
I am thinking that the coil may be on the way out. any thoughts

 

Welcome to the Forum. You can search old thread for loss of power.

 

Take the aircleaner cover off when it's cold and see if the choke is closed, then after warm up take off the cover with the car running and see if it's fully open, may need adjustment. Next thing I would suspect is vacuum leak. Check all the small vacuum hoses for cracks, etc. and replace all vacuum hoses if condition is unknown.
You can test the coil with a voltage meter but I'd have to look up the readings you are supposed to get between the + and - .
Jon

 

fuel pump?

 

The symptoms sound exactly like a bad converter. What year is the car? I would also check everything that Jon said.

 

thanks for the advice guys. coil resistances were out of spec. changed that out. engine starts easier but still hasnt solved the problem.
fuel pressure is about 5 psi. next gonna check the fuel filter in the tank and the condition of the advance diaphragm in the distributer. the carb is original and looks a bit tired after strip down, got a new 1 arriving today. have had a strobe on the spark plug leads and there is a consistent flash.

 

Vacuum adv. on dist. is easy to check and could be source of vacuum leak. Pop off the dist. cap so you can see the lever that goes into the vac adv. pull the hose from the carb and suck on it as hard as you can. You should see the lever pull into the vac adv, if not the diaphagm is shot in the adv. You will need the casting #'s off the dist to get the right replacement, I got mine from O'Reilly's. Casting #is on the large part of the dist facing the intake nomally.

After you check the vacuum hoses you can spray starting fluid (ether) around the intake edges with the car idleing to see if it changes the speed at idle, if it does you have a vacuum leak at the intake gaskets.
Jon

 

Check the spark plug wires. After the motor heats up, one of the wires could be resting on a header causing the wire to ground out and causing a cylinder to miss after the car is warm.

James

 

well finally tracked down the problem. Fuel pump is on its way out. new one gets fitted this evening and hopefully the problems are over.
thanks everyone for your advice.

 

i had a replacement fuel pump go bad on my 289 years ago while i was drag racing. it would start fine, then about 1/2 way down the track it would die. Then it would start working again after coasting back to the pits and cranking for a while...