Cadillac Repair: 1993 4.9L, fuel pressure gage, decent gas mileage

Question
I have a 1993 4.9 L Deville about 108,000 mi. Always had a slight hard starting problem imediately after shut off. Last week it would not pass the NOx test. Kind of reminds me of a vapor lock on an old Ford. Car runs great decent gas mileage first shift is a little hard. Driven only by my wife much too slowly. Really enjoy your answers.
Marty

Answer
Hi Marty, Thanks...its always nice to hear a good compliments. Sounds like you might have 3 issues going on here. With the hard starting you will need to hook up a fuel pressure gage to the shrader valve near the throttlebody and see what the pressure running. should be 40 to 50psi with the key on for 2 seconds or with the engine running 35psi and would go up to the 40-50 range with the vacuum hose unplugged from the pressure regulator. If the pressre leaks down it might come out the vacuum hose fitting so be careful. Otherwise look for a leaky injector or bad checkvalve inside the fuel pump. After the pump turns off pinch the RUBBER fuel return hose section with vicegrip pliers with very small teeth and that will test the pump. Pinch both fuel and return and that will test the injectors. If it doesn't leak now then the regulator is the problem. Remember to remove the pliers before turning on the fuel pump or damage can result. Then once the pump turns off pinch off the hoses again...NOx could be due to a faulty EGR valve or EGR solinoid. It might not be able to hold vacuum or it might have no vacuum to the valve...Hard shifting problems could be due to bad engine or trans mounts, low trans fluid, too high an idle speed, late shift because of a bad vacuum modulator, incorrect throttle valve cable adjustment or a mechanical failure inside the trans. Only you will know what you can put up with. If all gears are late then any one of those suggestions could cause it. If it is 1st gear only then probably a mechanical issue inside the trans. Hope that helps. Bill