My 67 mustang is a daily driver. It's all original and has 136,000 orig. miles on the 289 2V. It started running rough about a week ago. If I accel. too much, which doesn't take much, the car shakes and hesitates bad. If I accel. slowly, it gets up to speed, but takes awhile. I found it works best shifting the automatic tranny from 1, 2, then drive. Any ideas on a probable cause?

 

You probably need a tune up. I'd start there. Sparkplugs, wires, cap and rotor, points. PCV, gas and air filters. Change the oil too. Install items, set dwell and timing, adjust the carburetor and see where you stand. If you aren't able to do it yourself ask around local clubs to find someone who knows how to tune an old car.

 

Carb may need some attention. Or be a vacume leak

 

Carb may need some attention. Or a vavume leak?

 

If none of the above provide a desirable outcome it could be your fuel pump is no longer providing enough fuel to accelerate the engine so it drains the fuel from the floats then falls on its face once the bowls are near empty and it attempts to run off of the inadequate incoming supply.

Carter makes a nice 120 GPH pump that is built well.

If it comes to the point of wanting to test the pump you can remove the fuel line from the carb and place it in a glass jar. Crank the engine over for about 3 or 4 seconds. There should be more than a cup of fuel in the jar.

If not replace fuel filter and try again....If not replace pump.

-Gun