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Discussion Starter · #1 ·
77 RC-360-sniper efi-msd 6a-msd blaster 2 coil-magnetic pickup dizzy...been running just fine..tried to start this am and have non start.
I swapped 12v coils with an off brand out of my 48 CJ2A..still no spark..when jumping the mag pickup from the msd box I get coil spark so MSD says the box is good. When I check the coil or a plug wire..no spark. I'm confuzzeled. I have 6k psi of fuel pressure with key on and perfect flow at the EFI inlet..could it still be a coil issue? At 200k on the multi meter I have 5.1 and 200 I have .08. not sure if that helps..I think the magnetic pickup was around 230. Thanks all-James
 

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If you don't have a RPM reading on the Sniper it's a bad pickup or connection to the MSD unit.
 

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Number one cause of a no start with a Holley Sniper is loss of power during cranking followed by loss of RPM reference, easy way to test is plug in the handheld and then turn the engine over, if the power is interrupted the unit will restart or go blank, if there's no RPM shown during cranking then there's a problem with either the wiring or distributor.
 

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Discussion Starter · #6 ·
I think the sniper is fine...no interruptions..just tested the coil per Dodgeboys diagram and nothing...what's wierd is I tried a different coil yesterday (non MSD) and still no fire but that coil is fine as I reinstalled it in the Willy's and drive around this am..it's a 50000v coil..and I have spark via the msd coil when I jump the mag pickup..I don't get it..is there that much difference between coils? Happy Thanksgiving everyone and thanks
 

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Discussion Starter · #9 ·
Maybe it's bypassed somewhere in the loom..I didn't install the original msd..but it's still on the fender wired up..new coil installed for the heck of it and I have spark but no start still..I've dumped fuel into the EFI and not so much as a cough out of her. I did notice that my fuel pressure drops as soon as the pump cycles off upon initial crank..I don't think that is normal..I feel like it should stay pressurized. I already checked filter and flow at the carb and it seemed fine.
 

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Discussion Starter · #10 ·
Whoa..she just fired!!! Ok so if this ballast resistor is somehow still hooked up will it cause coil failure..this is the second time I've had to deal with this. Thanks
 

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Well..update..she only fires when I jump the solenoid...cranks fine with the key but no fire..jump the solenoid and it fires up😖
Which solenoid? I don't know your system. If you describe how a spark is triggered we may be able help you with the diagnostic
 

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Well..update..she only fires when I jump the solenoid...cranks fine with the key but no fire..jump the solenoid and it fires up😖
So the ignition is losing power when cranking, both the MSD and Sniper have to remain powdered during cranking, if the Sniper isn't losing power I'd see where it's power-on wire is and attach the MSD to the same wire, actual power for both units must come directly from the battery.

Font Rectangle Parallel Engineering Drawing


For whatever reason it sounds like the MSD is turning off during cranking, could be the ignition switch, ballast resistor or the ignition bypass circuit which I'm not sure of on a '77 model.
 

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Discussion Starter · #14 ·
The starter solenoid on the fender..pic attached..MSD tech said the box is fine as the led is on as it's supposed to be and I get spark when I jump the mag pickup pigtail from the ign box. So wierd that it starts when I jump the solenoid but not from the key..I wonder if the key switch is bad and not letting the signal go to the coil..I'll have to look into that now
 

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Discussion Starter · #15 ·
With a test light I have power at Run and Start at the ballast resistor (J9 pink) but not at the coil..still no start...with key on and I jump the solenoid I get power to the coil and it fires up. (I replaced the ballast resistor today) I start to think it's the ign switch but how could it only fail when key is turned to Start but doesn't fail in Run (it stays running)..seems like if the ign switch was bad it wouldn't power the coil via the ballast resistor at all.
 

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the FREE 1975 dodge truck factory wiring diagrams are on my site

 

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I start to think it's the ign switch but how could it only fail when key is turned to Start but doesn't fail in Run (it stays running)..seems like if the ign switch was bad it wouldn't power the coil via the ballast resistor at all.
The 70's switches did not power the run circuit in start. In theory, the ign got power from the start circuit Via the ballast bypass wire. Then when the key was released, it got power from the run circuit. I believe they did it that way so the alternator did not turn on until the engine was running, to prevent voltage spikes when turning at slower speeds.

You cannot just tie the two circuits together, or the starter will get power from the run circuit, and keep cranking, or just have lower voltage trying to actuate the solenoid on the starter. Later years got around that by having a separate terminal at the starter relay, that gives power for the ballast bypass, but is not tied to the start circuit.

There is no easy circuit that gives power in both start, and run. I just swapped over to the 80's starter relay, and used that bypass circuit to power the ignition in start.

.
 
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