electrical problem straight from purgatory

[pointman03]

Hey there folks, i have a 90 full size blazer that seems to be a srange bird.... the electrical side of the fuel delivery system wont work. It has a new computer, fuel pump, relay, oil pressure switch, and now an ignition switch.

no matter what i do, I cant figure out why the relay will not power the pump..... I dont seem to be getting voltage to the relay..... the fuses are good, the fusible links are good..... theres something called a fuel module thats under the dash, but its a circuit card and the chiltons manual i have only shows it in one schematic, and does not discuss its function. Haynes manuals do not even acknowlege it.... I may be missing ground somewhere, but where to start?????? if i apply power directly to the fuel pump, it will run, but i cannot get the injectors to fire into the throttle body... once again, no voltage to that part of the system...... Anyone got any ideas??? I'm about ready to pull my hair out.....

[pointman03]

ok, after a lot of wirechasing yesterday, the game has changed a bit. on ECM B in fuse panel, if i read across the socket, i get 12 volts to the computer. if i put a fuse in place, it drops to 2 volts. if i disconnect the computer, voltage jumps back up to 12. this is a strange one indeed..... the fuse checks good, as a matter of fact they all still read good.... anyone got any ideas on how to tackle this one????

better yet, anyone know the easiest way to rip the darned computer and TBI out and replace it with a carbeurator without killing the ole pocketbook????

[vman357]

I have the same problem (in the c/k thread)all i did was change my engine and tranny....I also don't have headlights either,acc's work,replaced a ton of parts too.
I sure hope someone can help us lol

Happy Hunting,
doug

[vman357]

I found the cure to my problem, I ran a new wire from the batt to the alt....That solved my problem!!!
Hope this helps you in your quest for answers !!

Good Luck,
doug

[amac209]

look for a voltage drop between the ignition switch ignition wire and the fuse box. i bet theres a bad connection somewhere causing extra resistance which is why your voltage drops to 2V when the circuits powered up. i assume the battery's good as well as all the block and body grounds as well as fusable links. try jumping 12V directly to the computer side of the fuse. I bet it will fire right up. check the wiring conection where it enters the fuse block. make sure all connections at the ignition switch are solid. good luck!!!