Hi all,
I need some help troubleshooting the TBI-injected 454 in my J-4000.
Last summer I parked it next to the house while I worked on my diesel Wagoneer; it was running, albeit a bit roughly, when I parked it.
Now that I'm dd-ing the Wag, it's time to freshen the J-truck up. Now it won't start, and it's obvious why: the injectors aren't spraying gas.
Here's what I've done so far, in order:
1. Siphoned all the gas out of the fuel cell.
2. Changed the fuel filter.
3. Purged the fuel lines by running the fuel pump, from a clean container of new gas into another container. The TBI return system just dumps it back into the container after a round trip. Refilled the fuel cell with 5 gallons of nice new clean gas.
4. Changed the engine oil and filter.
5. Removed the TBI unit, disassembled, and cleaned it. Note: Since I don't know Jack about them, I did not do anything with the injectors.
6. Reassembled the TBI unit (old gaskets) and put it back on.
7. Used all new vacuum fittings where I could, including the caps on unused ports.
8. Removed old distributor cap and rotor. Marked spark plug wires with 1-8, in order. Got a new distributor cap and rotor.
9. Removed the distributor and spun the oil pump for about one minute.
10. Reinstalled the distributor, realized I hadn't marked it properly as to the position of the rotor.
11. Turned the engine by hand (breaker bar on crank bolt) to 10 degrees BTDC
12. Installed new rotor. Reinstalled distributor, aiming the rotor at #1 on the distributor cap.
13. Installed cap and spark plug wires, following timing 1 8 4 3 6 5 7 2 as marked on intake manifold.
14. Used Optima battery from the Wagoneer; 454 spins happily, not any indication that it's trying to fire.
15. Put the hood back on (my weightlifting workout for the day).
Whew, ok. That was last weekend.
This week, got a new battery.
1. Installed battery.
2. Jumpered fuel pump, watched pressure gauge. Steady at 13psi.
3. Removed the hood, 'cuz I knew I'd need to address the distributor. Curse those GM engineers: distributor in the back. What were they thinking!
4. Checked every connection to the TBI, coil, distributor, sensors. Everything is tight and clean.
5. Checked connector to CPU (under dash, no exposure to the elements).
6. Dropped some gas directly onto the butterfly valves.
7. Engine started for a moment, actually runs pretty smooth, and then ran out of gas.
7a. output port of injectors are bone-dry.
8. Have GF turn the key while I check voltage at injectors. Steady 9-10 volts. I thought at firing time they are supposed to pull to ground?
9. Try priming a couple more times while fiddling with distributor (timing). I think I'm close enough for it to start if it wanted to try.
9a. I thought I might have installed the distributor 180 degrees out, but if I'd done that, it wouldn't run at all, would it?
So what's happening? Is there some reason the CPU wouldn't allow the injectors to spray - a sensor is bad, or disconnected, or fuel pressure is low, or? What else can I check? I'm thinking of getting a rebuild kit and two new (not reman) injectors today.
I'm pretty much grasping at straws here now. Help!