1994 S-10 Blazer 4WD Fuel Problem--Help

[seanfriddle]

Check for 12 volts @ pcm pin #E16 that will be the blue plug, orange wire. That is the battery power to pcm and it is always hot. If you have intermittant power at that pinout or there is no power at all, it is more than likely that there is a bad splice in that circuit. If you have 12 volts @ fuel pump relay but no pwr @ pcm check the big wire loom behind the ac pump going to firewall (passenger side). There is a splice there that connects fuel pump relay and oil pressure sending unit and then goes to the pcm. Oil pressure sender and fuel pump are on this circuit and that splice gets corroded causing intermittant power or total loss of power. Haynes or chilton manual won't inform you of that. Remember, orange wire, big loom. If you find the problem to be something else, keep in mind what I have described for future reference. Hope this can be of help now or later. By the way, fuel pump relay along with horn relay is behind dash right above the transfer case shifter. The door and light buzzer is there too.

[Fireplug]

Oil pressure switch could be bad in 1994 the power goes to the oil pressure switch and if the switch is bad it will cut power to the pump

[dreamweaverzink]

Have you checked the coil, modulator, and pickup? My 94 Blazer 4.3 Vortec had similar symptoms. After replacing many parts (all new fuel related components) I found the defective part to be a bad pickup. Once replaced the problem disapeared. Mine would start and run until it got hot, then shut off until it cooled, at which point it would start right up. Not sure if there is any way to actually test the pickup, but you can test the coil with a voltmeter, and the modulator can be tested at O'Reilly's once you remove it. That would be something worth checking if you haven't already.