Intermittent stalling

[slow72]

**I've also posted this in the electrical section i just thought it would get more traffic here. Move/delete if necessary.

For starters i've got a 72 GMC with a 250 in it. The PO added an HEI distributor and did away with the resistor wire for the points setup. The problem i'm having is the truck starts and runs fine, then after a few minutes of running the idle becomes very choppy and then it eventually stalls. It will restart after a few minutes but acts the same way.

I've replaced the module and it didn't help at all. However when checking for power at the distributor when it was running i was only getting 6 volts and when it begins to run rough it bounces between 6 and 0 until finally stalling at 0 volts. The power wire runs from the distributor to the ignition terminal on the solenoid. With the engine not running i get 12 volts at the ignition terminal and at the distributor. But when running, only 6 volts.

What's going on!? Thanks in advance!

[Shyguy]

Try hooking the wire for the distributor to the positive teminal of the battery and see what happens. If it works when you do this you will know that the problem is in the ignition switch, associated wiring or coil.

I did not have a key for my truck so I hooked up to the positive terminal with a toggle switch and it works great.

My truck has a '70 250 l6 with a later year HEI also.

Danny

[tomtuna1978]

when you say the power wire is run from the solinoid ... what do you mean by that ? ... the starter solinoid on the starter? if thats the case ... i would run the ignition wire directly from the ignition switch to the distributer.

[Longhorn Man]

the dist should not be run to the starter solenoid. There shouldn't even be any power there when the engine is running.
Run the wire to the ignition unfuses terminal on the fuse block in the cab and see what it does.

[PanelDeland]

Try reading this thread and it should help with any wiring issues.I used it and had my HEI done and driving in about 30 min. with zero problems.It contains part #'s and exact wiring changes.

http://67-72chevytrucks.com/vboard/s...d.php?t=148346

[slow72]

Thanks guys. I'll try hooking it to another power source and trying that tomorrow.

Longhornman - The solenoid has two terminals besides the large one for the positive wire from the battery. They are labelled 'S' and 'I'. The S terminal is only energized when cranking and the I terminal should have 12 volts when the key is on (which it does, but not when running). I'm thinking something went wrong inside the solenoid since it's been running fine for the 3 years i've had it and who knows how long for the previous owner.

[john]

I think the I terminal supplies 12V only when key is in the start position. Follow longhornmans directions and it should work.

[Camper Power]

the I terminal should only have power during engine cranking, the purpose of it is to supply enough power to the points style ignition for it to fire the engine, without it the starter would draw all the power and the igntion wouldnt be working properly. but an HEI ignition doenst need the I terminal.

[Longhorn Man]

neither of those two terminals should be powered unless you are twisting the key to the start position. If it's been working fine like that, then it is an act of god, becouse there is no way it can physicly happen.

[ERASER5]

"If" the original white wire is gone, then it was replaced with another one. The new wire still has the "Y" split going to both the coil and the "R" terminal on the solenoid. The power at the "R" terminal on the solenoid is coming from the coil power wire, not the other way around. This the way the original wiring is. For an HEI, ALL of the original coil wiring should be yanked both yellow and white. Only the purple wire should be left on the start solenoid. A new wire should be installed from an ignition source to the coil.

[slow72]

Well everyone here was correct about that terminal. For some reason i thought it was the other way. Sorry Longhorn Man! Anyways the problem is now solved. After peeling away old crusty electrical tape and looming i discovered that the old resistor wire was still in fact there as well as about 5 wires spliced into it that went to nowhere with barely taped up ends that i'm assuming were shorting out causing the stalling.

I got rid of the resistor wire and useless wires and ran a new wire from the connector on the firewall following the HEI thread posted earlier. Now it runs like a top! Thanks everyone!