97 tahoe running rough/hard start

[GoTeam]

I have a 97 tahoe that has run great up to a month or so ago (158000 miles). It started running a bit rough and the SES light had come on. I checked it with scan tool and it said multiple misfire. I replaced the plugs (NGK V Power), the spark plug wire (Bosch), and the cap/rotor (Standard Ignition). When it is cold it starts right up and idles smooth until the engine gets warm. When it is warm the engine runs very rough. It never cuts off but just idles rough and even seems to be rough when accelerating and cruising at times. Also when it is warm the gas pedal must be depressed a bit for the engine to start without cranking for an extended period. I have no SES light on now and no codes. I sprayed carb cleaner around the intake while running and no change in engine speed. If anyone has had this problem I would sure appreciate a e-mail or an answer to this thread. It drives me nuts driving it like this!!!!

[jonnik]

Originally Posted by GoTeam

I have a 97 tahoe that has run great up to a month or so ago (158000 miles). It started running a bit rough and the SES light had come on. I checked it with scan tool and it said multiple misfire. I replaced the plugs (NGK V Power), the spark plug wire (Bosch), and the cap/rotor (Standard Ignition). When it is cold it starts right up and idles smooth until the engine gets warm. When it is warm the engine runs very rough. It never cuts off but just idles rough and even seems to be rough when accelerating and cruising at times. Also when it is warm the gas pedal must be depressed a bit for the engine to start without cranking for an extended period. I have no SES light on now and no codes. I sprayed carb cleaner around the intake while running and no change in engine speed. If anyone has had this problem I would sure appreciate a e-mail or an answer to this thread. It drives me nuts driving it like this!!!!

My wife's Tahoe was doing the same thing-I changed intake manifols gaskets to no avail. It turned out to be the fuel pressure regulator. It is inside the intake manifold (on VIN R) and a bit of a bear to get to. The diaphram was leaking and dumping fuel into the manifold, hence the "rich mixture" code. Get this replaced soon, because I took too long to figure it out(DUH) and cooked my catylist.

[010175]

I have a 1999 suburban that was hard to start when warm. I the tail pipe was soot black. It would start right up when cold. It turned out to be the fuel presser regulator was leaking. It took about 6 hours to change but fixed the problem. To test the regulator you need to hook up a fuel presser gage and see if it will HOLD 57 to 62 PSI. Mine would have the presser (62 psi) and then when I turned off the power it would drop to 20 PSI within seconds. Do a search in suburban for fuel presser regulator for more help. Dave