Ignition Issue

[67ChevNut]

Hey guys, looking for some help.

My C10 won't start, won't even do a click when I turn the key. I have replaced the starter, the ignition switch, the battery, all is new. The wiring that goes to the starter is not that old either, bought it new at some point. My truck has a 350 tbi engine, the fuel relay won't click and the fuel pump is not working either.

I have replaced the ecm too yesterday, from a working suburban. Still not even clicking when I turn the key, lights do work though, but not the signal lights, I don't know if that matters or not. I tested the purple wire with a light tester, there is not voltage apparently in it with the key turned. I checked for bad fuses, the fuse going to the starter is good, and the fuses inside the cab. I should add that I also added an extra ground wire from the frame to the battery. I spliced it together with the one from the engine to the battery.

Truck starts if I jump wire the selenoid, directly from the starter. It would only start for a second or two since there is no fuel supply, I have to use starting fluid just before jump wiring it.

What else should I check? I have not checked the junction box wiring that is by the fender next to the battery. What should I check there? I am hoping the fuel pump is not working because it isn't getting voltage due to a wiring issue, not sure at this point if the fuel pump is bad yet.

I am sure feeling frustrated with this truck right now. I hope you guys can help me, I will certainly appreciate it.

[Sheepdip]

Check/prove your battery connections first, then the ignition switch to make sure it's good, if all is good take on and prove 1 issue at a time to pin point your problem.

90% of electrical problems are grounding issues, not saying that's your problem but keep it in mind

[RustyPile]

ECM?? Fuel pump relay?? What are we working on here??? LS swap?? 86+ square body??

In any case, I'd look at the fusible links first.

[67 twins]

I'm just completely baffled by the title of your thread. You have a starter problem not an ignition issue.

[A1971Blazer]

If it starts by jumping at the solenoid then it's not the starter.

You mentioned that there is no voltage to the purple wire, are you checking it at the starter? The purple wire is the hot wire that engages the starter, it passes through the neutral safety switch on the column near the firewall. unplug it there and jump across the connector to see if that fixes it. The starting circuit is independent of the LS harness, or should be in most cases.

The fact that your fuel pump doesn't come on,, also indicates that there is no voltage going to the relay that triggers the fuel pump.

If it's an LS then you should get a 12v signal to the ignition relay as well as the fuel pump relay when you turn the key to the run position. If not there are a couple of fuses or relays in your swap harness that could be faulty.
Did you do the swap yourself?

[68 C10 Driver]

67ChevNut, I am with SheepDip, all the things you listed should only be active (receive 12vdc) when the ignition switch is on, I would definitely do a quick checkout the ignition switch.

[truckster]

Start simple. As SheepDip said, start with battery connections. Use a test light to check for 12v at the starter switch. Verify that the "run" position is energized. Verify 12v when you turn to the "start" position. Make sure you get 12v at your fuel relay when the key is initially turned to the "run" position.

In other words, perform a trace from where you know you have voltage (the battery) to where you lose voltage. That's going to be where you problem is.

[Wrenchbender Ret]

Like the guys say, take the test light & trace the circuits. A wire diagram will be a great help. First thing to look at is in back of the ign. switch. These are notorious for the connector in back of the switch to get hot & burn the connector & terminal.

George

[67ChevNut]

Great advice, I'll try to get my truck to work tomorrow and post my results.

My truck is actually a 69 with a 67 front clip, has a 350 TBI engine. Installed that engine in it several years ago. Doing a LS swap soon, but like to fix this issue before getting started on that.

Thank you so much

[Minkota]

try bypassing the Neutral Safety Switch.

[4x4 k1500]

Are you sure you did not get the small wires to the solonoid reversed I mention this because when I removed the starter on my K1500 to rebuild it some time lapsed and I reversed the wires. Took the starter back off switched the wires,and presto--fired right up

[67ChevNut]

I checked the fuel relay connector by the firewall, there is no power when I turn the key in it, it does have a constant hot connection, but all the other pins don't work when I turn the key.
I also removed the wire harness connection to the fuse box by the firewall, I checked the purple wire connection with the test light with the key turned on, nothing, no power.
I checked the junction connection near the battery, on the fender, there is voltage, that connection is good.
I strongly suspect the problem is inside the cab, between the ignition switch and the fuse box, guess I should check all wiring going or coming from the ignition switch. Is there anything in particular I should be checking under the cab, what wires come and go to the ignition switch?
I will check the selenoid wiring to make sure, and I will try a jump wire at the neutral switch.

[Sheepdip]

See Post #2

[RustyPile]

Originally Posted by 67ChevNut

I checked the fuel relay connector by the firewall, there is no power when I turn the key in it, it does have a constant hot connection, but all the other pins don't work when I turn the key.
I also removed the wire harness connection to the fuse box by the firewall, I checked the purple wire connection with the test light with the key turned on, nothing, no power.
I checked the junction connection near the battery, on the fender, there is voltage, that connection is good.
I strongly suspect the problem is inside the cab, between the ignition switch and the fuse box, guess I should check all wiring going or coming from the ignition switch. Is there anything in particular I should be checking under the cab, what wires come and go to the ignition switch?
I will check the selenoid wiring to make sure, and I will try a jump wire at the neutral switch.

Make note of the sentence in bold in the above quote.. The purple wire is not hot with ignition in the ON position --- only in the start position. It energizes the starter solenoid. The purple wire comes off the ignition switch and goes to the neutral safety switch, and on to the starter.

Here's how I check that circuit.. Disconnect the purple wire at the starter in order to deactivate the starter and attach a test light to the wire.. Turn the ignition to the START position and the light should come on. If it does, you have starter problems. If it does not come on, Move the light to the Neutral safety switch. Ignition switch to START again. Probe both terminals, should have voltage on both terminals.. If so, there is a break or disconnect in the wire going to the starter. Suspect #1 would be the firewall junction box. If voltage only on one terminal, check for misadjusted or bad NS switch.. If no voltage on either terminal, move test light to the purple wire at the ignition switch.. Turn it to START again.. If no voltage, either ignition switch is bad or wire(s) are loose at the terminals.. If there is voltage, you have a break or disconnect on the purple wire between the NS switch and Ignition switch.

[67ChevNut]

Rustypile, thank you.

I found a break on the purple wire near the starter. Also, another one at the constant hot red wire going to the ignition switch.
I had installed one of those quick disconnect connectors by the starter, but the connection was too weak and came loose. Same thing happened by the ignition switch when I replaced it.
Engine turns over with the key on now! It doesn't start though, it appears that I do have a fuel pump problem. I'll be checking the fuel realy and the fuel pump today. Truck is been parked for about a year now, I guess in-tank fuel pumps go bad when not used. Any advice on checking for issues with the fuel pump?