So my 91 TA 5.0TPI 700r4 car has been giving me headaches this last month. First the fuel pressure regulator failed. Mechanic replaced that then fuel pump failed. Mechanic says fuel pump was probably failing all along, and it killed the regulator on its way out. Ok, so those being new, tonite after a 45 min drive in rush hour, the car began stalling. First at a redlight, then while cruising thru my neighborhood. Was running about 200 degrees, has over half a tank of fuel, volts look fine on the gauge. When I got home, i checked it out. Vacuum lines and plugs all look in place. I start the car and let it idle. after 30sec or so, it stalls and the fuel pump runs for a sec and it shuts off too. Then the fans came on. Did this 4 times in a row, fans only came on 2 of those times. Any thoughts???

 

Does the engine start right up after stalling? It may just be an idle control issue. Does the idle seem low? Does the idle increase when you turn the AC on? If not, you may have an Idle Air Control or IAC circuit problem.

 

yes, it will start back up pretty easily. the idle does get low right before it dies while driving it but while just running in the driveway its smooth right up until it dies. thanx alot for the insight and ill definitely be investigating that tomorrow....

 

Ok so i couldnt wait, and i just went out and played with the car for a bit. It didnt stall, and the idle didnt go up when the ac came on but it did drop for a second once the ac was engaged but almost immediately it righted itself. is it possible that the Idle air control valve could malfunction after a long drive, or when its warm?

 

It's very possible that the IAC could suffer a heat related failure. In fact that's not unusual. I would like to see you connect a scan tool and watch desired idle vs. actual idle. Also use a two channel lab scope to view the control signal to each of the two IAC coils simultaneously. I have seen the IAC drivers in the ECM fail. If you could view the control pattern, you should see clean on/off 12V signals to each coil. If you see noise or a rapid cycling signal, you have a bad driver. You could very well also have a bad IAC. It is a fairly complex little mechanism and I have replaced several of them.

Assuming you don't have ready access to a lab scope, you might try at least finding a scan tool. The older OBDI scanners are fairly cheap used. I hate to promote replacing parts without verifying failure, but you might just try replacing the IAC. Be sure to perform the minimum idle adjust afterward. Otherwise it may take some time for the idle to stabilize.