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Old 04-05-2012, 08:39 PM
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weirdest electrical problem ive ever seen need ideas

so i have a professional products tbi fuel injection system on my sbc and im running a msd e curve distributor i have it all wired up the way they intend it to be
on the fuel injection
rred wire- 12v constant
orange wire- fuel pump
black wire- neg of coil
yellow wire- keyed 12v

and on the distributor
red wire- coil pos and switched 12v
orange wire- coil neg
black wire ground


well first off i tried starting the car and had no luck and i noticed i had no spark so when i started checking into it i found that i had power on both sides of the coil(not sure if thats supposed to be)
now the weird part is that when i pulled the distributor to spin it and check the trigger and at first i got nothing but after a second i began getting spark kinda intermittently but at least i was getting something the i n oticed that when i did get a spark the fuel pump would come back on

so in other words when i trun the key to on the pump would come on build pressure and turn off and then when i started spinning the distributor by hand the pump would kick on every time i got a spark

if anyone has any idea what the hell is going on please fill me in lol
anyway i decided to wire the professional products using the existing green wire which means i had to run my ignition box in conjuction wire the distributor but that enables me to use the tach out put from the box as my reference to the throttle body instead of the coil neg

what do you guys think?

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Old 04-21-2012, 07:13 PM
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I saw this post before, and the one thing that struck me right away was you said the black wire goes to the coil negative.
Where does the EFI unit get ITS ground from?
Maybe you could post the schematics for the efi and dizzy, that may help sort things out.

Last edited by LATECH; 04-21-2012 at 07:14 PM. Reason: spelling
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Old 04-21-2012, 08:14 PM
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From HERE:

The EMS grounds through the mounting of the throttle body.

Black Wire - Negative side of coil if using a ready-to-run two wire distributor. No amplifier box.

The connections should be soldered, be sure the TB is grounded, be sure there are no pins bent in any of the connectors.
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Old 04-22-2012, 08:51 AM
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Quote:
Originally Posted by Pupsvette76
so i have a professional products tbi fuel injection system on my sbc and im running a msd e curve distributor i have it all wired up the way they intend it to be
on the fuel injection
rred wire- 12v constant
orange wire- fuel pump
black wire- neg of coil
yellow wire- keyed 12v

and on the distributor
red wire- coil pos and switched 12v
orange wire- coil neg
black wire ground


well first off i tried starting the car and had no luck and i noticed i had no spark so when i started checking into it i found that i had power on both sides of the coil(not sure if thats supposed to be)
now the weird part is that when i pulled the distributor to spin it and check the trigger and at first i got nothing but after a second i began getting spark kinda intermittently but at least i was getting something the i n oticed that when i did get a spark the fuel pump would come back on

so in other words when i trun the key to on the pump would come on build pressure and turn off and then when i started spinning the distributor by hand the pump would kick on every time i got a spark

if anyone has any idea what the hell is going on please fill me in lol
anyway i decided to wire the professional products using the existing green wire which means i had to run my ignition box in conjuction wire the distributor but that enables me to use the tach out put from the box as my reference to the throttle body instead of the coil neg

what do you guys think?
If the negative side of the coil is not pulsing while cranking the distributor is not working. This is basics of the basics. If you put a test light on the neg coil terminal and crank the engine it needs to flash. It wont run if it doesnt.
I am not familiar with your FI system be I am guessing they are grabbing the same pulse off the negative coil wire. Seems kind of hokey to me.

Check the distributor, make sure the distributor is grounded.
MSD stuff usually has a decent troubleshooting section in the instructions.
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