Won't start till cranking stops?

[vikingsandpintos]

Hi all, finishing up some stuff on my daughters truck so we can get plates and insurance going!

Got the new automatic trans in it, started it last night, and have an odd problem. The truck will only start when you stop cranking it. While it is cranking, it won't fire, but as soon as you stop cranking and the key goes to the run position, it fires up. it is a 67 C10 2wd, the previous owner switched the distrib to an HEI. It was a manual trans, I just changed it to automatic. In the process of that, I took the old starter off that had 3 wires, the big one from the battery and 2 smaller ones that went to the 2 small terminals. The new starter only has 1 small terminal, I thought I put the correct small wire on it and left the other unhooked as per another post, but maybe I did something wrong?

I'm not sure where or what to check, seems like there was something I read about distrib wiring about this, but can't seem to find it now, of course! lol Any direction or suggestions would be great, thanks! Earl

[NaturalSnapple]

Sounds like your coil is only getting power in the run position. Double-check your wiring and make sure power is applied to the coil in the crank position.

[davepl]

Sounds like no power in crank. HEI needs to be powered by a circuit that is hot both during crank AND run.

IGN_UNFUSED is likely a good place to start.

[bigrigpardo]

the issue that you are having is that in these trucks the small wire that you left unhooked is what sends power to the coil in the crank position. right now you have no spark while cranking but the coil gets power the minute the key hits the run position. so you can either get a different starter or find a new terminal on the fuse box that is hot in the start and run position and run a new power feed to the hei. I vote for the second option.

[HO455]

Most likely the second wire you left off is the yellow wire which is supposed to go to the IGN post on the starter solenoid. That post would supply 12 volt positive to your coil when the engine is cranking from the starter power. Hooking the yellow to the same post as the purple wire should give you power to the coil when cranking. The problem is that you are adding the load of the coil and ignition circuit to the solenoid circuit which can cause other starting problems. Ideally you want a starter solenoid with the two small posts. And hooking the yellow lead to the battery lead will fix the starting problem but now you can't shut the engine off. So that's not an option either. Here is a link with a lot of information on the starting circuits.

http://67-72chevytrucks.com/vboard/s...d.php?t=454737

Why did you swap starters? You should be able to put your old solenoid on your new starter. Or obtain the correct solenoid. They are not hard to get.

[HO455]

Why did you swap starters? I would obtain the correct solenoid or swap the old one on to the starter. The correct solenoids are not hard to get.

[VetteVet]

This is a common problem with the one terminal mini starters. You are only applying power to the coil in the run position from the key switch. The 67 switches are different from other later years as they have no accessory position.

Your two small wires to the starter are the purple 12 gauge and a smaller 16 gauge yellow wire. The purple wire is the starter solenoid wire and the yellow wire is the ignition resistor bypass wire which sends voltage to the OEM coil for starting with a full 12 volts, but only while cranking.

Since the PO has installed the HEI distributor, he has probably disconnected the small yellow wire since the HEI requires a full 12 volts at all times. This is probably the reason you don't have voltage to the distributor during crankiing.

The solution is pretty simple, but first you need to establish where you are powering the HEI from. As was said if it's from the IGN-UNfused terminal on the fuse panel and it has power while cranking you are good. It seems that you are not getting power there while cranking or you are powering the HEI from another source. Possibly the firewall block where the original resistance wire was located which the PO might have eliminated to run the ignition to the HEI.

If you find that the IGN-UNfused terminal has power in the cranking position with the key switch then all you have to do is switch your distributor ignition source wire to that.

You can't just run a jumper wire from the purple cranking wire to the distributor because you would continue to feed the solenoid when the truck starts and the key is returned to the run position. You have to cut the power to the distributor as soon as you release the key to run or the starter would continue to turn.

Here's a couple of easy fixes.
1. Run a wire from the purple wire to the distributor and tap it into the ignition power wire say it's a 12 gauge red or pink wire. This gives you ignition voltage while cranking.
But remember I said that would feed the solenoid in the run position. To prevent that all you need to do is solder in a small diode in the jumper wire and you would get the cranking voltage but the diode would stop the feedback.

2. Install a Bosch relay in the ignition wire and run a wire from a hot source, battery positive to terminal 30 on the relay and run another wire from terminal 87 to the distributor wire feed. Then run a small gauge wire to the relay from the purple wire to terminal 86. Then run a ground wire to terminal 85 on the relay and the relay will send
ignition voltage to the distributor whenever you hit the starter. when you release the key
the ignition voltage will run to the distributor.

Even if you replace the starter you will still have to run the small wire to the distributor.

[vikingsandpintos]

I will have to look at it this weekend. The reason I changed starters was because the original one was for the manual trans bellhousing on the truck that had 3 bolts.. When I changed to the automatic trans, I had to put the starter on it that bolts to the block with 2 bolts. And of course, couldn't be easy and have 2 small terminals, it only had one. I had posted a question about the wiring a while back when I did this, and someone replied to just hook up 1 small wire and leave the other unhooked. (I don't remember the colors offhand) . I need to look that thread back up, I guess either I read it wrong or had some incorrect info... Prob my fault though!! lol