Got the P300 code, multiple misfire. 2002 Blazer, not just a code as it is actually misfiring. Sometimes I don't think I'll even make it home. Has mostly been sitting for 6 months since this started happening.

New:
Distributor Cap and Rotor
Plugs
Wires
Fuel Pump
Spider Injector

Local shop said it was the Fuel pump, which it wasn't.
Other local ship said they don't know.

Getting to witts end. Any suggestions?

 

The best thing to have next is a look at live misfire data to see if its random cylinders or if its only one cylinder and how bad is the misfire. Also we need any stored codes. If you don't have a scanner with live data/misfire capability there are a few cost effective solutions using a BT dongle and inexpensive android software. The next step up are a number of dedicated scanners that can do a lot.

This targeted approach made very quick work of a misfire on my Toyota SUV last year. It was one cylinder on live data. I swapped coil packs (10 min) since thats a common problem with this engine and the misfire followed the coil pack. New coil pack to replace the known bad component and we were done. No guessing or shot in the dark parts swapping. Now they are not all that easy and obvious but that's where we start.

What brand is the fuel pump? Have you done the fuel pressure sticky test?

George

 

No coil packs on the blazer.

Don't know what brand pump. The shop put it in.
What's the fuel pressure sticky test, but really, putting in a new fuel filter, fuel pump, and fuel spider injector, what's left to fix as far as fuel pressure goes?

And thank you for the reply.

 

I know that the Blazer has no coil packs and uses an old school single coil and distributor. I was just using my most recent example of using diagnostics to quickly asses and fix a misfire to encourage you to take that route. I strongly encourage you to get live misfire counter capability and report back. Absent this data you can look at spark at the plug ends of the ignition wires to see if you have 1" of strong blue spark as a first order test of your ignition circuit.

These engines are very picky about the brand of some of the components. AC Delco or Delphi is almost always best in these cases. This is true of ignition components and its really true for fuel pumps. Some members report having to replace some aftermarket fuel pump brands multiple times where a given pump lasts for a week. There is a test at the top of this forum for testing fuel pressure. If your problem is not found in the ignition circuit, verifying proper fuel pressure function can verify a proper and durable repair. Also there can be wiring/ground problems even if the pump itself is OK.

George

 

Thanks, I'll look for the fuel pressure test.