My 1996 chevy blazer starts right up, runs and idles fine, then cuts out after about 30 seconds, as if someone turned the key off. It will instantly start up and sometimes do the same thing again. Then, once again it will start (sometimes briefly at high idle)and run without problems for an extended period of time. Then, after the car is turned off and I restart it, the event repeats itself. Occassionally it will start and run all day with no problem. When it is running , it does not hesitate or run rough. I have replaced the ignition control module, ignition coil, air filter, egr valve and cleaned the maf sensor. I have run techron through the system. There are no codes. It has been doing this for weeks with no change, any ideas? Thanks

 

a friend of mine had a late 80's blazer with a similar problem. it would start right up, then about 45 seconds later it would choke out. long story short it turned out to be something with his EGR system. Id start looking there even though you replaced the EGR valve id test it and make sure you didn't get a bad part.

or maybe try a fuel filter and fuel psi. maybe the pump is going bad and will slowly leak down psi.

 

I suspect an ignition switch issue...I had it happen to my 97 Jimmy. Good luck!

 

Thanks for the suggestions, I will try checking those issues.

 

Do you have a tach? If it's ignition, the tach will drop straight to zero while engine is still turning.

Did you have the codes read?... could be something there that hints at it. EGR problem would show.

Has it died, lately, at a stop sign on exit ramp?

 

I had a similar problem on my 01 blazer. It happened after we replaced the intake manifold gasket. It would start and idle high then it would run fine then die. It turned out to be that I broke the PCV valve elbow. I replaced it and now I don't have that problem. The only problem I have now is I am coding P0122 then p0341 which is throttle position sensor and camshaft position sensor. The only thing I haven't done is check the timing with the distributor. Truck runs fine except it stalls when I come to a stop in reverse.

 

Try turning the key on/off 3-4 times BUT never all the way to the start position until the last time.

 

follow this

96+ Fuel System Diagnosis - Blazer Forum - Chevy Blazer Forums

dont start guessing like others are doing

 

Awesome details.