Stumped & at a dead end

[1990DangerRanger4X4]

1990 Ford Ranger 2.3L. As I said in my earlier post, I have spark but no fuel. I have replaced the fuel injection relay, ignition relay, and the ICM module. I located the ECM in the passanger side kick panel and replaced both the grounds for it. I am worried the ECM itself is bad because of corrosion caused by moisture from a hole in the floor board. As you can see in the attached pictures, it looks pretty corroded. I removed the fuel injector wiring harness to make sure all the wires are fine, which they are. The only other 2 things I can think of to replace which I havent already are the crankshaft position sensor and the idle air control valve (IAC) but if the IAC was bad it should start just not run right. If anyone can give me some guidance I would greatly appreciate it. I only have another month to fix it as I am PCS'ing back to the states from over seas.

 

[black_demon69]

inertia switch, fuel pump, wiring in between fuel pump and relay. just a few suggestions....

 

[1990DangerRanger4X4]

The inertia switch is good, brand new fuel pump. I have fuel pressure at the test port, but the injectors don't pulse.

 

[black_demon69]

verify injector wiring is where i would start but going by pics ecm is probably the culprit.. i would in any case fix hole in floor board though.

 

[1990DangerRanger4X4]

As far as I can tell all the wiring looks fine. When it died going down the road, all the gauges went hay-wire malfunctioned then turned back on and the fuel and spark cut out. Now that I have spark after fixing the ICM and fuel pressure by hot wiring a toggle switch to the fuel pump all that's left is to figure out why the dang injectors wont pulse. As far as I can tell its got to be the ECM which ties into what the gauges did I believe.

 

[Spott]

Fuel injector pulse is tough to verify without some fancy equipment. Most people don't have an oscilloscope at home.

If you have a college nearby with an automotive program, I'd go talk to the dept head. They have all the tools needed for full- (or over-) diagnosis, and won't charge for labor if you show up during lab time and let the students under the hood. It might save you a lot, if you can verify that the computer is or is not the problem.

 

[adsm08]

Injector pulse isn't that hard to check. Get a small light bulb in a socket, plug it in in place of an injector, and then crank the engine. The light should light up dimly.

If it doesn't, first check for power, then use a test light from the battery to the injector plug to check for ground when cranking.

 

[snake]

Crank angle isnt bad if you have spark. Send that pcm to ecmtogo.com they can test and fix it in a day. The website has their number

 

[Spott]

Injector pulse isn't that hard to check. Get a small light bulb in a socket, plug it in in place of an injector, and then crank the engine. The light should light up dimly.

If it doesn't, first check for power, then use a test light from the battery to the injector plug to check for ground when cranking.

Oh, you techs and your nifty tricks. I'm gonna have to write that one down, for the days I don't want to dig the O-scope out from under the mess on my electronics bench.

 

[RonD]

Just to confirm, the engine will start/fire if you add fuel manually, i.e. spray gas or ether(starting fluid) into the intake and then crank the engine.
This would mean CPK sensor and ICM are working.

The Crank(CKP) sensor connects only to the ICM(ignition control module) and '90 doesn't have a CPS(cam position sensor), so computer(PCM) only knows to start the fuel injectors when it gets the "timing" signal from the ICM.

But with fuel pump relay not working(controlled by PCM grounding it)
And with fuel injectors not working(also controlled by PCM grounding them)

I would suspect PCM fault

Pins 58(tan wire) and 59(white wire) on the PCM are the ground pins for the fuel injectors, '90 is Batch Fire so only 2 ground wires are needed for 4 injectors.
If you were to ground wire 58 or 59 with key on you should hear 2 injectors click open, but be careful, you don't want to dump too much fuel into a cylinder and hydrolock it.


Pin 22(light blue/orange wire) is the fuel pump relay ground, if key was on and you grounded that wire, fuel pump should come on.

Pin numbering for Ford EEC-IV CONNECTOR here:
http://www.auto-diagnostics.info/ford_eec_iv

Connector pin numbers not PCM pin numbers
You could also check ground pins 16, 20, 40, 46, 60, just to be sure they are good grounds.

 

[4x4player]

If my brain looked like that, I would replace it. (stop laughing)
Do your testing after you have a brain installed that isn't corroded.
C'mon, would you test sensors if your battery terminals looked that bad?
Just sayin'