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Discussion Starter #1
I have an 89 W150, 318 automatic. There is no spark, and no fuel. The check engine light never came on. Would the Hall effect cause this and or the starter relay ? I have no voltage at coil, checked primary lead and read around 5 ohms. Bought new coil, and checked it before I installed it and it read the same ohms. Is that what they are supposed to be?
 

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Welcome to Allpar. The Starter Relay would not cause a 'no (+) power' situation at the ignition coil. The Hall effect possibly, read on.
The starter relay controls the starter solenoid only and your engine does crank over with the starter OK but won't fire up, correct?
The Hall effect provides the cylinder firing signal to the PCM which will then switch the ground side of the coil and injectors to provide the spark and fuel pulses.
If you are not getting 12 volts (+) at the coil Gy wire, then trace that wire over to the ASD (automatic shutdown) relay. It becomes a Dk Gn/Bk wire at a splice along the way.
Be forewarned that if the engine is not cranking over or running, the ASD relay will stay off and you won't have (+) power at the coil or injectors. The PCM will ground and turn on the relay through the Dk Bu/Yl wire when it sees firing pulses from the Hall effect, unless the PCM has a defect.
The old coil probably isn't the problem if you have the same symptoms with a new one. Some diagnosis may help to determine what needs to be done first.
Using this wiring diagram below as a guide, check the ASD's Rd wire for battery power all the time and Dk Bu wire for ignition power with the key-on. The ASD Dk Gn/Bk wire should have power with the engine cranking over.
All powers and grounds must be present at the PCM.
Do some preliminary checks and let us know what you do or don't find.
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My '89 had the factory engine control module, as yours probably has. It is mounted to the driver side inner fender. It could be toast. Can you see any fuel pressure at all?
 

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Discussion Starter #4
Thanks, guys. Taz, I thought of that also and I'm not getting any pressure at all. Imperial, I will check the I asd today. Thanks again
 

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Discussion Starter #5
roadkingdave said:
I have an 89 W150, 318 automatic. There is no spark, and no fuel. The check engine light never came on. Would the Hall effect cause this and or the starter relay ? I have no voltage at coil, checked primary lead and read around 5 ohms. Bought new coil, and checked it before I installed it and it read the same ohms. Is that what they are supposed to be?
Every thing checks out and points to the engine control module. Ordered one from auto zone and I'll let you know how I make out with it.
Thanks guys for your help.
 

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Discussion Starter #6
tazdevil said:
My '89 had the factory engine control module, as yours probably has. It is mounted to the driver side inner fender. It could be toast. Can you see any fuel pressure at all?
I am not getting any fuel pressure at all. Can't hear the pump, and I know that as soon as you turn the key to start the engine, your supposed to get 2 squirts from the injectors, but not getting that. Also, no power on the positive side of coil when cranking engine, put new asd in and same thing. From what I've read online, and in the repair manual, it looks like it's the engine control module. They are a little hard to find, but I found one at auto zone, special order. I'll let you know how I make out when the new module comes in. Thanks.
 

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Primary coil resistance should be between about 0.9 ohms and 1.3 ohms. 5 ohms is way off. I'm concerned that you haven't done complete diagnostics, and that the new ECM will not fix the problem. These very rarely fail. You should have jumpered around the ASD relay and the fuel relay first to see if the fuel pump runs and if you can get spark.
 
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Discussion Starter #8
Bob Lincoln said:
Primary coil resistance should be between about 0.9 ohms and 1.3 ohms. 5 ohms is way off. I'm concerned that you haven't done complete diagnostics, and that the new ECM will not fix the problem. These very rarely fail. You should have jumpered around the ASD relay and the fuel relay first to see if the fuel pump runs and if you can get spark.
I bought another coil, primary resistance is now at 1ohm. How do I jump the asd? I also spent 3 days searching for the pump relay and could not find it. I pulled the ecm and checked the condition of the circuit board. Found that some of the rubber insulator that protects the board was melted around one of the heat sinks was actually coming off the board. It may be a rectifier, not a heat sink, not positive, but either way it is not soldered to the board so that area of the ECM would not be working.
 

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I'd recommend trying the new coil with the existing ECM now. It's not at all unusual that after 24 years, some of the potting compound would deteriorate.
 

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Just as soon as the new computer gets here I'll let let you know how it does. Looked for the fuel pump relay again today, still could not find it. But I did jump a hot wire to the green/blk wire and the I heard the pump start running.
 

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Some vehicles share one relay for ASD and fuel pump.
 

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Bob Lincoln said:
Some vehicles share one relay for ASD and fuel pump.
That's what I thought. Is it the ecm causing s very low voltage at the coil positive wire (Grey) and a very low voltage at the Green/black wire. Voltage at Red on relay is battery voltage, but its only about a quarter over a volt at the wires I mentioned. When I crank the engine, iseither getting no voltage or the same .25 voltsat the coil positive and the green/black wire, which if followed it runs the pump. I put battery voltage to the green/black wire, and the pump ran. Is the asd bad? Or is it the ecm?
 
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