Electrial Gremlins: New Ram-Jet

[paulmoon]

First off, Thanks to all those who have knowingly and unknowingly helped me with this project! Many searches through the forum archives have answered many questions for me.
Here's a problem I couldn't find an answer to. I installed a new 350 ram-jet in my 73 blazer. Upgraded the alternator, added electrial fan, updated single pole starter, wiring harness for EFI ,and replaced old damaged wires in engine compartment. The engine will turn over but no spark at the plugs, unless I run a wire from the battery to the fuse box ( I'm attaching it to the same fuse as the air pump and the EFI wiring harness). Then, the engine will start and run well. To stop the engine I need to remove the wire or it won't stop running even with the key off. If I leave that wire connected to the fuse box, the fuse box remains "hot" with some accessories left on. Is this a wiring problem between the key and the fuse box or between the battery and the fuse box? I'm not very good with electrial. Clearly, I've miss wired something or removed a neccessary wire.
Again, thanks for the help. Shouts to Dontoe, and Poohbair. PICs of the progect are on my website.

 

[TWISTEDJACK]

Sounds like that wire needs to go to the ignition source.

 

[paulmoon]

"ignition source"? Like from the large wire on the starter? (then to the fuse box)
BTW what's Boise like? My daughter is moving there tomorrow. I'm driving her there and leaving her with the old subraru. Job market? Apartments? Cost of living?

 

[TWISTEDJACK]

What I mean it switched source. Get a test light and find a source on the fuse block that is only hot when the key is on. The weather is good raining on and off this week. 4 wheeling rocks only 30 minutes away. Well what they say when the Cailfornians move in they never leave. No offence just mean that people like it here.

 

[dyeager535]

So do you have 12V to the coil with the key in "run" and no "additional" battery wire hooked up? It sounds like that's your issue, but I'm not familiar how those older (assuming this is the 1973) glass fuse panels are wired. Sounds like your coil isn't getting power...would explain why it runs with the key off.

One thing I'd do for sure is seperate your power leads from each other. You can get power from the same source (battery, fuse panel, however) but IMO you really should fuse them seperately. In this case, you wouldn't even consider the other wiring, fuse, etc., to be a possible culprit. Now if you blow that fuse, you'll lose everything connected to that fuse, and in the future, that will make any diagnosis necessary (short in air pump wiring? How will you narrow it down?) much easier.

 

[paulmoon]

No power to the coil with the key on is the problem. I think I need to wire it differently that's for sure. I have to find a wire off the ignition to tap into. Hopefully that will do it. Thanks.
Boise sounds OK. Hope she likes it there. Thanks.

 

[paulmoon]

What I mean it switched source. Get a test light and find a source on the fuse block that is only hot when the key is on. The weather is good raining on and off this week. 4 wheeling rocks only 30 minutes away. Well what they say when the Cailfornians move in they never leave. No offence just mean that people like it here.

Hey Keven, actually I think my daughter is nuts to leave Truckee! Lots a good stuff to do here, she justs wants to leave the "home" town. Get away from the parents and all. Idiaho is nice though. We looked at it years ago before deciding to move to Truckee. I might still end up there. (another Californian )

 

[ramjet gmc]

i read your post and do not understand a dam thing you have dun

but on your old wire harnes ther is a wire (purple i think) that went to the dis you will need that for your new harnes -- that is like the werst part of the install the other 3 are simple -- but i mixed up the fuel line feed / return but fixed it

 

[Ryan B.]

No power to the coil with the key on is the problem. I think I need to wire it differently that's for sure. I have to find a wire off the ignition to tap into. Hopefully that will do it. Thanks.
Boise sounds OK. Hope she likes it there. Thanks.

yep sounds like your figuring it out.
I used my old HEI hot wire for the 12v coil wire when i swapped over to TPI.

i also found a single prong that was hot when the key was in the RUN and START position, and doesn't drop much voltage when you're cranking the starter... that goes to the ecm.

 

[paulmoon]

That's what I need to find. A prong that's hot with the ignition on and while cranking too. I was afraid that this post would sound confusing!
Explaining wiring problems when you don't really understand electrial well is just plain hard! But, It sounds like the advice I've received will clarify the situation here. The new engine sounds great and runs strong out of the box! I've got 4:88's with 37" MTR's. Just have to work out a few bugs.