I have a 91 ford mustang with approx. 93,000 miles on it 4 cyl auto, while driving down the road the car just stops running. No warning, like you turned off the key. When hooked to a computer it comes up with a code secondary fuel system failure according to the haynes manaul which also says beyond the repair of a home mechanic. The car will also shut off sitting in the yard at an idle no specific tme limit sometimes 10 minutes, sometime an hour any help would be appreciated. I have replaced the fuel pump and the air idle solenoid by recomendation of a friend which didnt help thanx NOTE: the car starts right back up. What is the secondary fuel circuit? And what can cause this problem?
Put a fuel pressure guage on it. You should have 29 to32 psi. While you have it running watch the guage. When it dies notice the pressure. If it falls you could have a bad regulator. You should hear the pump running. If the pump isnt running could be a bad relay.