eaglescout526

So unless the ECU isn't switching the injector fully, or the injector isn't wanting to operate correctly, it just won't fire or at least it tries to.

I don't think the orientation matters for the injector, at least I haven't seen anything that denotes orientation for it.

Lol lets not do that again shall we? No blockage in the fuel line so that's good, pretty cool to learn that it just pours right out during crank. So I'm not sure how the ECU controls the injector, my guess is the ECU has a switch or control chip inside that switches on/off for the ground of the injector to pulse. Other than checking for the Ωhms resistance, I am not sure how else to test it. I mean it was tough to tell if the ECU was truly switching the injector with the noid. I might have to take a test light and see if I can see what this dimming looks like.

Have you tested your CPS for Volts AC? Should put out above 3.5VAC. Huh, I mustve not submitted my reply when I typed what to check.

Ah good, you caught the keeping it plugged into the harness. I thought about mentioning that. Well when it does the prime, fuel will come out of the hole in the TB for the injector for a second. When you go to crank or apply voltage to the pump it should just come out, we aren't looking for pressure, more or less seeing if fuel flow is obstructed or not and seeing if maybe the injector could be at fault.

Hold off on that for a moment. I remembered something from when I rebuild my throttle body. If you were to remove the injector there are two holes, one for input and the other for return. I am wondering if we can observe how the fuel comes out from there.

Basically like fuel was just trickling down the TB. Or kinda like when you have fuel in a carb and enough comes out and the engine kinda catches but its not enough to keep going?

Very well could've been. Still need to figure out this fuel problem. So pump constantly running with 12V applied and relay in place, it kinda wants to start but it acts like its not getting enough fuel to meet the demand of starting. Sound right? So I wonder if power loss is at that bulk head met with resistance from the tar inside. Just a working theory for now.

Heyyyyy the ISA works!! I know that sound after shut down anywhere. I think we are moving away from the bad ECU idea.

Yes and no, I would hold off on the pump thing until we get this fuel injector thing figured out but it could be the pump, but 3-4 volts still doesn't sound right unless that's all it really needs but if that was the case then why would they have put a ballast on the later years?

That just doesn't sound like enough voltage for anything. But even applying 12V directly to the pump itself yielded near firing of the engine.

I still wonder if the fuel pump can put out but not enough pressure to keep up with the demand of the ECU and engine. Like yes we saw the pump can build the pressure but can it maintain that pressure when fuel is needed?

You snagged that one? Nice, looks good!

What Ωhm said.

On the pump itself should be two prongs. If the clips are attached wrong, the pump will blow bubbles and if they are clipped on the other way, it pump the fuel. But one of the wires going to the pump should be black indicating ground.

No little baby alligator clips laying around? Something like this makes me want to get a bunch of the weatherpak connectors and just make test connectors for power and ground like for the sending unit.

Oh ok. Makes me wonder if the fuel pump runs, but its not putting out enough pressure weather it is resistance in the wiring and connectors or the pump genuinely failing. But that's good that it primes, that takes care of that wonder.

Alright we are getting somewhere. Now we just need the fuel to get to the TB and keep the engine running. Pressure at the rail with this new development?

Relay or jumper in? Cranking or key on?

Just short of a miracle worker lol.

Good thing I got that Jeep/Eagle bolts bolts book. PN J0273573 is 5/16th in diameter, 18 in thread distance from tip to tip, 0.620 in shaft length and its made of steel.

Neither TBI or electrical book says. Let me go look at the 2.5L and FSM.

Maybe, just maybe. I'm crossing mine too.

So I wonder if that ground and the one that goes to the ICM come back to the dipstick ground. The one with the four splices is ground splice "D" that probably goes to the dipstick. On that second splice is a 20, 2 18's and 2 14 guage wires with a 14 going to the grounding point. Meanwhile the ICM ground and O2 sensor come together on probably the same eyelet at the dipstick.

Well with key on, I don't suspect there to be any voltage going through 87 until crank sequence. So O.L. would make sense to not be seen there as the relay isn't energized. I wonder what the second splice feeds then. Most if not all black wires in the harness are ground. But why would there be voltage there?