I have 1998 Chevy Blazer 4.3L V6 Vortec 4dr 4wd.


A couple of months ago I had bad fuel pump. I replaced it ( Delco, of Course ), fuel filter, plugs, wire, cap and rotor. I was going over steep hill and gunned it and that SES light started to blink and stayed on until I arrived to work. I went to lunch and the SES light was still on. When I left for the day I noticed that the SES light was off. The next day the same thing happen, gunned it and the SES blinked and stayed on.


The SES goes on and off periodically. The error code I keep getting is P0300.


Multiple Cylinder Misfire Detected. I cleaned the MASS, Throttle Body and EGR. And the SES went away but turned as I gain speed and my RPM's go up.
Any suggestions

 

Have you looked through The dreaded P0300 CAUTION LONG POST?

 

P0300 is most commonly caused by a fault in secondary igniton, low fuel pressure or volume, incorrect camshaft retard adjustment, or a worn distributor gear. Are your distributor cap, rotor, & plugs all AC Delco? If not, that would be the place to start looking for a problem.

 

Yes. All AC Delco

 

I realize you've replaced the fuel pump, but checking the entire fuel delivery system would confirm or eliminate the possibility of other problems with it. This link will help. Post all 4 readings and we can analyze them: https://blazerforum.com/forum/2nd-ge...eakdown-88305/


There are other things to check as well, and we can get into them if necessary, but checking fuel delivery is something you can do yourself.