1989 GMC Sierra Engine Stalling and not restarting

BOBBY WITT

MEMBER
1989 GMC SIERRA
V8
4WD
AUTOMATIC
5,000 MILES

OK here goes I had the trucks computer read for a code because it keeps stalling while in drive the codes that showed were one for the O2 sensor and GM Code 42 in which I have no idea on where to start with this code because it has a newly rebuilt engine and transmission also I just recently had this truck in the garage again because of this problem and the mechanic had told me that the distributor had went out and he replaced it I got it out yesterday and drove it last night and it drove fine for a while till it reached normal opperating temp then started doing the same problem as before now it wont start at all

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Hi Bobby Witt, Welcome to 2carpros and TY for the donation

now it wont start at all

Lets do below to determine if its fuel or spark issue and get back with some testing results we start here.

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, cap and rotor, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing