Small Block & Big Block Chevy Specific - TBI Injection Gurus?

We picked up an '89 GMC Sierra a couple weeks ago and have been doing the routine maintenance that was neglected. Yesterday it up and quit running. It got to the point where it'd stumble if given gas in idle, but not when put into gear and under load.



Of course, my first thought was an empty tank. We ruled that out. Next, I thought it was the pump, so we pulled the line and found flow. Then, we figured maybe it's the rotor on the dizzy. Replaced that, to no avail.


There's something up with the injectors. It'll run if you dump gas or spray carb cleaner into the throttle body. The injectors weren't engaging, so we straight wired one to the battery. It gets fuel and squirts pretty well when hotwired. This leads me to believe it's a relay or fuse related problem. When I get off work, I'm going to run a test light and see if it's getting a pulse. Any thoughts?

Fuel pump is weak. Had it happen to me anyway.

Thought the same, myself. However, the injectors pulled fuel when straight wired.

Yep, mine did too, was just weak and not enough to keep the engine running for long.

Gotcha gotcha. It did kind of dribble on idle and flowed half-assed under throttle. It wasn't that conical-shaped shower you'd normally get. When I get the chance, I'll run a test light on the things to see if they're even getting a pulse. I appreciate the input.

Pressure should be about 15 or so if i remember correct.