Only Runs While Starter is Engaged??? In need of some HELP

[CobraJetKid]

Got a 1970 Ford Bronco with a 302 from a 1974 Bronco. It all started when I lost spark after replacing the plugs, wires, cap and rotor. In troubleshooting I also replaced the coil and points/condenser with a Pertronix ignition module to find out later that the new rotor I got was no good. This is where I'm at now. As stated, the motor will only run while the starter is engaged. It fires first click of the key. You can rev it up so long as the starter is engaged then it dies as soon as power gets cut to the starter. I cannot figure it out. I've tried everything I can think of. First thought was ignition switch but I disconnected it and hooked the coil and module straight to the battery. Same thing. Replaced the coil and starter solenoid. Same thing. Jumping the starter solenoid. Still dies as soon as you remove the screwdriver. Anybody know what's going on here because I am now completely lost.

 

[tinmanxx]

Sounds like you are only getting power to the coil through the bypass at the solenoid. If you were running points ignition power was run thru a resistor and the starter solenoid bypasses the resistor during cranking.
Check for ignition power at the positive side of coil, it should be 12 volts. The resistor is no longer needed with the electronic ignition so by pass it for full voltage to the coil.

 

[CobraJetKid]

Yeah my first thought was something in the ignition circuit but it still dies as soon as the starter stops even with the coil and ignition module hooked straight to the battery.

 

[Joe473]

When you release key solenoid and ignition terminal on solenoid that bypasses resistor wire drops out.

Pretty sure pertronix module and coil will not run through resistor. 70 may not have ballast resistor may use resistor wire under dash and is not obvious. Eliminate resistor wire or try temp wiring pertronix module and coil direct to battery with fuse jumper as test.

 

[oleguy74]

When you release key solenoid and ignition terminal on solenoid that bypasses resistor wire drops out.

Pretty sure pertronix module and coil will not run through resistor. 70 may not have ballast resistor may use resistor wire under dash and is not obvious. Eliminate resistor wire or try temp wiring pertronix module and coil direct to battery with fuse jumper as test.

pertronix will run just fine with ballist res.mine has for 10 years.ign sw is most likely the culprit.

 

[bwyman]

The Pertronix electronic conversion needs at least 8.5 volts to run where points run on 3 volts. You may need to step up the voltage to the red wire on the Pertronix. The best way to install the kit is to connect the red wire to keyed 12v,black wire negative coil. keyed 9v to 10v to + side of coil.

 

[CobraJetKid]

It's not the ignition circuit. I've hooked up the module and coil straight to the battery and disconnected the wires from the starter solenoid. Even with the ignition hot wired to the battery and jumping the starter solenoid it still dies

 

[KBUCK1]

Ignition switch

 

[englewoodcowboy]

As stated earlier, when you are cranking you are getting power to the coil via the i terminal on the starter solenoid and it bypasses the ballast resistor. I would check to see if you have power on each side of the ballast resistor in run. I suspect your ballast resistor is bad or you have a break in the line between the switch and coil.

 

[DirtDonk]

Ok guys, he's said at least three times that he's tried BYPASSING ALL THAT STOCK WIRING by connecting his module and his coil directly to the battery. So none of that old stuff is even in the equation at that point.

Yes, he's got a resistor wire. All EB's did from the factory as far as I know. Maybe some very early ones didn't, but I've never seen a separate ballast resistor that wasn't owner installed.
And yes, under normal circumstances, it's an easy diagnosis to say it's the ignition switch and only the starter relay is supplying power. But he's bypassed all that and it's still not working.
Which we gotta admit CobraKid, is very strange. So this might take some time.;D

Got any pics of the wiring under the hood you could post up?
Are you sure you have the jumper wires good and tight when testing?
Are you re-using any of the old noise suppressor choke/capacitor/condenser thingies? If so, unhook them first.

pertronix will run just fine with ballist res.mine has for 10 years.ign sw is most likely the culprit.

For once I disagree with your wording oleguy! Yes, some run their Ignitors just fine on low voltage. But most can't. Pertronix specifically says it should have the full 12v available, and that it might not run correctly with less. And we've diagnosed many times here poorly running Ignitors from the power supply being too low.
So while you're technically correct for yours and some others, it's not a universal truth.

Can you show us just how you're connecting all this stuff CobraKid?

Thanks. And good luck.

Paul

 

[abn373]

I had this exact same issue 2 months ago when I switched to a GM HEI distributor. I am trying to think how I fixed it. It was all about the wiring (improper routing not failure), not failed parts.

I will try and look when I get home later if its not solved on here by then.

FWIW, I ran a ballast resistor with the pertronix set up I had on prior to replacing the distributor. It is now removed, along with the coil, now that I have HEI. Talk about a much simpler set up.

 

[DirtDonk]

Simpler is right! But what about clearance? Did you have to do any mods to make it fit?
Sorry to get sidetracked off the OP's question, but I was curious.

Paul

 

[abn373]

I didn't really have to do much. I got one of those already converted to fit a Ford style GM HEI modified distributors. It even came with a new set of Accel 8mm wires precut cut with correct ends and sized for a 302.

It was a tight fit with that intake manifold vacuum port T fitting. I had to just slightly file the exterior bottom ring of the plastic cap. (just a little) but that may be because I have an Edelbrock Performer 289 intake manifold so the fitting location may vary with other manifolds.

My hood is the standard fiberglass hood with the center "bubble" There was no height clearance issues. The install would have went easier except I failed to mark the location before pulling the old distributor so I managed to put it together 180 deg out like a dumbass. After that was fixed and I figured out the wiring issue that was causing the same problem the OP is having, it timed up very easily.

Best $100 project I have done.

 

[DirtDonk]

The install would have went easier except I failed to mark the location before pulling the old distributor so I managed to put it together 180 deg out...

It's funny how a job with only two choices, so basically a 50/50 chance of getting it right, and it seems like 90% of the time it's wrong!

Paul

 

[broncnaz]

Definetly a wierd problem. Try cleaning the grounds. Might want to pull the dizzy and make sure the block and the base of the dizzy are clean. It might be having some wierd grounding issue.
About the only other thing I can think of is you have some other issue. maybe the alternator is bad and back feeding power. Might try unhooking it and see if it makes a differance. On the same note if that dont work try unhooking the sending units for water temp and oil pressure maybe one of them is gounding out causing a issue.

 

[Slowleak]

I think I would be giving Pertronix a call.......

 

[broncnaz]

Another option would be to reinstall the points and see if it runs. Then you it would directly point to the pertronix having a issue.

 

[DirtDonk]

Probably something obvious we're missing.

I would also (from past experience) ground the distributor body to the engine.
Yes, it's "supposed" to ground through it's own contact, but with rust and oil as possible insulators between the two, a separate ground is often a fix.

We fixed a no-start situation once by spinning the dizzy in the block for a couple of minutes to clean off and improve the contact. Went from a non-starter to an instant vroom just from doing that.
Been grounding them myself ever since.

Worth a shot anyway.

Paul

 

[Dbarnes72]

I know you've ruled this out but I just had a very similar problem. GM HEI module, Duraspark knockoff dizzy. Would fire while cranking and not run in"run". Mine is a Centech harness. I had it wired with the white "coil +" to the coil. Changed that over to the blue "ignition" wire. Problem solved.

 

[brianstrange]

Are we missing something important? Is there a Duraspark module in the truck, or just a points distributor? It could be the wiring to your Duraspark. If no duraspark, try to connect the coil directly to the battery again. Maybe something odd happened the first try? If no Duraspark, and it's starting during crank, but not run, it either a switch or resistance wire. If there's a second resistor on there, that could be your issue as well.