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Discussion Starter · #1 ·
I need some help from the experts I bought this 90 w150 guy said they parked it one morning then the next it wouldn’t start it’s been sitting a few years I’m not getting any spark and the fuel pump is not coming on I’ve got power on 2 of the wires on the asd relay If I jumper the blue/yellow wire to ground the fuel pump will run and power to the coil but no spark the coil and ecm were replaced a few years ago when it did the same thing Will the coil pick up keep the ecm from triggering the fuel pump relay
 

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ASD powers both fuel pump and hot side of coil. The computer based on seeing input from the Hall effect in the distributor grounds the coil to control timing. You first need to find out why the coil side of the ASD is not getting power from the Ecm. Is the computer getting ignition power from the ignition switch?
 

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computers do not like switching positive wires on/off SO they use relays , and switch the grounds for the relays on/off ( no voltage spikes into computer )  ,, So your asd has 2 power IN leads , one from your key for "ON " one from battery for "heavy" load ( coil + and many other things like injector + ) the computer "sees" crank from dizzy pick-up , then puts GROUND to the asd which connects the power from battery ( charging system battery lead)  TO the coil etc , the computer then switches the coil's GROUND - negative side ON/OFF to fire the coil ... follow the coil + wire back to asd , follow the asd "key switch ON" lead back to key , opposite it is the ground for the asd , it runs to computer ( pcm) photo enlarges on a P/C , from a 1990 factory book .  the things that often fail are the pick up under the distributor cap and the relay itself , both "cheap enough" to replace as a TEST .
 

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you can do whats called a "scratch" test on the coil / while you have the ASD jumped you use a test light hooked to the NEG battery terminal and touch[scratch= quick tap] the Neg side of coil with the test light , if the coil is good it will fire a spark [ either use a spark tester or position coil wire a 1/8'' from metal ground]

if you email me [its below] l,ll send you the diagnostics to test the Dist pickup, include ALL info from this post
 

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they have a timer on them , when ya turn to "ON" it'll run 3 or 4 seconds then quit , UNLESS the pcm gets a crank signal . fuel pump itsself has a ground near the tank , that bad or pump bad , no run... so there is a coupla why elsis ...  plus bad connections somewhere , e mail dodgeboys ......
 

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Is the Ecm getting power from the ignition switch? Somebody post the Ecm connector I can’t remember the pin....
 

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power your test lite , look for ground FROM the pcm TO the asd . the pcm does not supply power to the relay .
 

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Discussion Starter · #11 ·
dodge82273 said:
power your test lite , look for ground FROM the pcm TO the asd . the pcm does not supply power to the relay .
If I jump the blue/yellow wire on the asd relay to ground then the fuel pump turns on and I get 12volt to coil but still no spark
 

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sounds like the pcm is notgiving the asd ground , now why ?  you need to remember it will only give ground for a FEW seconds , while it "LOOKS" for a signal from the cam sensor ( pick up in dizzy) . so the wiring from the cam sensor TO the pcm , the wiring from the pcm TO the asd , and the pcm are suspect . (as well as the replaced cam sensor ) unless you have another pcm to "TRY" I would not just replace that , I'd test the sensors and wiring from them  pins 4 24 and 7 tell the pcm what the cam sensor see's , you need a wire diagram e mail dodgeboys include info and see if he has one , or do a search of this site .. 
 

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Did you test the coil by any chance?
 

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Discussion Starter · #14 ·
Really thinking ecm because im not getting any thing to the asd even when you first turn the key on and All the wiring checked good coil primary and secondary checked good
 

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get a pin out for PCM connector , one you can read , mine was bad ( sorry , but I tried ) , check for power/grounds INTO pcm with out 1 of them it can't send signal TO asd ...  there are both keyed and battery power shown TO pcm , and a coupla grounds as well ...
 

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Discussion Starter · #18 ·
Ecm pin out was good I replaced the ecm now the asd relay cycles fuel pump runs but still no spark I checked the 3 prongs on the coil pick up plug with the asd jumped I hade 8volts on one and 4 on the other is the 3rd a ground
 
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