HELP!!! 2 bonnevilles down

[trab]

First time on.... I have 2 of my family's Bonneville's down.2000 and 2002 SE They both have stalled while at 55mph. they would start but not run more than a second. Start and die 20-30 times. next day start up on one , the other not always.the fuel pressure is there and a new pump was installed on the other. No codes except IAC motor stuck on one which is probably unrelated. The start/stall seems like a security fault which wont let the fuel rail do its thing,but the security system wont stall the car out. They both stall sudden with no hesitation,like the key is turned off.they both start at the turn of the key. Is there something that will stall a 3800 and also activate the security system to not let the fuel rail activate. they both run fine now but cant be trusted to drive to work, or college. Tx

[J Wikoff]

The IAC is pretty important to starting and idleing. It's the path for air intake when you don't have your foot on the gas. Though wouldn't cause a stall if you do have your foot on the gas.

If the security light isn't blinking at you, I'd suspect the crankshaft position sensor.

[trab]

its possible that the stalls occurred when the peddle was let off with normal driving .Could it stall when you just let off the pedal with IAC problems and start / stall?? One is at a garage with a friend Mechanic . I could just start replacing things but it would be a guess

[crash93ssei]

I would also suspect crank position sensor. They often will fail but not completely die and not give a code, they will warm up and die then literally be fine again as soon as you hit the key or won't start again for an hour or more.

[PopaTim]

Having been there myself, I'm in with the CPS crowd if its still does it after you replace the IAC. At least swap it with the one that isn't getting the iac code.

[trab]

both stalled when warm driving at 55-65 mph both would fire up at the turn of the key but only run to a rpm ,maybe 1000 and die immediately. I have read that a different module controls the start to about 400 rpm then another mod takes over. Would a cps stall a car and prevent a fuel rail operation but let the initial startup to happen?

[bobgto65]

CPS problems can be intermitted so yes.