Hi, I am completely at a loss. I have this blazer that we fixed up and drove it for 4 months. We replaced the fuel injector, the fuel pump, part of the fuel line, the coil & ignition module, the distributer cap and rotor, plugs and wires, and most of the sensors on the engine.

Now we can crank it cold and it runs for about 10 to 15 minutes and start spitting and sputtering and quits. We have stripped down the wiring harness to look for shorts. Running it at night we can see a blue flash at the back by the fire wall behind the right head. Then the ignition module melts.

I thought we fixed the short but it still does the same thing. I think I need to find a aftermarket wire harness.

 

There is a ground connection on the back of both heads. Most of the bolts are metric; but mine where standard, I think 5/8's. Perhaps for a check would be to take your jumper cables and go to the negative on your battery and connect to the engine.
L

 

So just an update we took all the grounds loose on the engine (I found a diagram of where they were) and cleaned them even the ground points on the chassis and under the battery. It still runs for about 10 to 15 minutes and starts spitting and sputtering and dies. I have no idea what it could be. I'm looking at replacing the wiring harness.

 

So start by putting a fuel pressure gauge on it (go do the loaner thing at your local parts store) and running it until it dies. Report the pressures. If nothing found there we will move on to the next thing. Don't care if it has a new pump on it, just please do the test.

 

The sparking is worrisome but yes, try the fuel pump test first. The sparks might be independent of the real issue. Aftermarket pumps are notorious for failing.