I've got a '90 Dakota that won't start. When I crank the motor, I'm only getting millivolts to the coil. The battery is at 12.5 v or so. All of the other electrical works fine. I'm pretty sure the ASD relay is working because I still have fuel pressure. I'm not sure what to test next. Could it be a bad pickup sensor in the distributor? How can I test the hall effect pickup sensor?

I appreciate any help. Thanks

I don't think it's related but had a 32 code as well. Says it's an open or shorted condition detected in the EGR solenoid circuit or a mechanical problem found in EGR system.

 

Ordered a factory service manual. My Haynes wasn't cutting it. I'm hoping the FSM will have a more compete diagnostic instruction. I'll post up after I fix it.

 

You say you have fuel pressure, if you used a gauge to check, you should be able to bleed off pressure and see it rise again to about 31 psi at the next crank (just so we know we're not looking at residual pressure).
If you had an o'scope, you could visualize the output of the pick-up. The signal goes to the PCM on pin 44 of the PCM connector. Eight Volt power for the pick-up is shared with the crankshaft sensor. This power comes from pin 7 of the PCM and ends up at pin 1 of the pickup connector on an orange wire. With key on, you should see a solid 8 V there. Failure of either sensor can affect the other.
You may test the output of the coil by applying 12 V intermittently and checking for spark to ground across an eighth inch (or so) gap at the output of the coil (be careful not to jolt yourself ).
EGR failure can cause issues with the vacuum system, good practice is to at least test for vacuum leaks. Better is to pull it and visually inspect it as well. Hot exhaust gas can melt a hole in the barb on the plastic body of the vacuum transducer (part of the EGR). Anybody who sez the EGR doesn't affect drive-ability, I beg to differ.
It should go without saying, but I'm saying it anyway, check "The Splice".
Great move getting a FSM, you won't regret it. That said, diagnostics are generally covered in a separate volume titled Powertrain Diagnostic Procedures. Often the steps therein require a DRB II tool, but there is still lots of additional guidance that makes the book a great tool in itself.

 

I didn't test the fuel pressure with a gauge. I loosened the fuel line coming out of the fuel filter. It drained out fuel and lost all the pressure. Then when I turn the key on, fuel sprays everywhere.

I did the failure to start test in my FSM. I didn't see a spark after grounding Pin 19 of the SBEC. So I suppose that means my computer is good. I can get a spark from the coil if I jumper the battery directly to it. According to my manual, that indicates faulty wiring. I noticed the ground strap that's bolted to the back firewall looks pretty rough. Where it hangs down and touches the bundle of wires by the coil, it's burned through all the plastic and I can see a bunch of wires. None of them looked burned or worn through the insulation, but I'm sure that's my issue. It shouldn't be getting that hot and melting stuff.

Also, when I hook 12 volts up directly to the positive end of the coil, I can hear my fuel pump kick on and stay on the entire time there's power at the coil. I don't know if that's normal or not. To me that could mean I've got a short in my wiring and it's energizing my fuel pump when I put voltage to the coil. I'm not much of an electrician but I think that's the most logical place to start. How should I go about running this down?

Thanks

 

Yeah, tracing the path from the coil to the pump takes us thru the ASD and fuel pump relays. These are only energized, I believe, when, at start-up, the ignition switch furnishes juice to both via Splice and wire A21 (Dark Blue wire) and the PCM provides ground to the coils for one or two seconds only, unless it detects the distributor pick up signal indicating a running engine, in which case, the relays remain energized. If the pump is running with juice at the coil, Key Off or Key On Engine Off, this leads me to conclude the relays must be getting ground via a short. The ground for the relay coils is pin 51 (Dark Blue/Yellow) of the PCM.
Real good troubleshooting, by the way.

 

 

Well, since 2013 I hope so. 😊

 

[QUOTE=1982kz750n1;3063805]I've got a '90 Dakota that won't start. When I crank the motor, I'm only getting millivolts to the coil. The battery is at 12.5 v or so. All of the other electrical works fine. I'm pretty sure the ASD relay is working because I still have fuel pressure. I'm not sure what to test next. Could it be a bad pickup sensor in the distributor? How can I test the hall effect pickup sensor?

I appreciate any help. Thanks

I don't think it's related but had a 32 code as well. Says it's an open or shorted condition detected in the EGR solenoid circuit or a mechanical problem found in EGR system.[/QUOTE

 

1990 Dakota crank no start, no power to coil. (Truck had periodically stalled/restarted in the past). Tapped on ASD relay, it started. I plan on buying new ASD relay. I tried replacing alternator and coil before doing research on the matter. ASD relay was mentioned, so I tried "technical tap" on it...Bada Bing!

 

Take your neg batt cable off turn your key to on put your finger on the asd connect the cable if you feel it click and you hear the fuel pump time out this circuit is not your issue.