The Stovebolt Site Forums The Shop Area Engine Shop My engine cut out, then ran fine?

So how do,you test a well running truck?
If it stayed dead I could follow protocol.
Stock pretty fresh full pressure 235/rochester/langdon Hei/power supply thru relay for hei, this engine starts darn near first tick every time…WAG which is not how I like to roll but…. is the hei module getting too warm in the dizzy? The dizzy only feels warm to the hand…. I have seen Jerry’s discussion on using electrical multimeter test lead wire to relocate module out of the distributor, do I just do that or ???? I just hate guessing….

I think this is the second time it has done this, the first time I was low on fuel so that one was a maybe. That time was just a short drive.
This time/ today I was driving the truck back into San Francisco from up north (San Rafael) where it usually resides.
Today 40 minutes into the drive I get into the city just a few blocks from destination, was after 15 minutes of stop/go stoplights urban stuff I’m stopped on a slight grade and engine shuts off like I turned off the key. Turn the key (key starter) and starter/engine spins fine but acting like no spark ( ie: r r r not even trying to start).
Look under the hood, glass filter at carb shows full of fuel, fuel pump glass shows full of fuel. Check that plug on square coil is attached, good..
Jump in the truck and let the grade roll her backwards 500ft (against 4 o’clock traffic, always fun) back into a bus stop.
Here’s the hard part….hit the key/starter and she fires up on first tick and drive 5 minutes to my garage, she’s running like nothing happened.
I thought the first time I might have fuel delivery issues as I was low on fuel, so I reviewed the piping from tank to carb, since it looked sketchy with old plastic inline filter, old line to pump and copper from pump to carb, so drained the tank, pulled out/replaced tank fitting and replaced all with nice cartridge filter, formed all new lines etc to pump and carb.

Chuck

sounds electrical if it just shut off.

Also look at your ignition switch and related wires as in the process of restarting you may have moved things enough that the power to the ignition was restored.

The original HEI distributors had one green and yellow wire going to the center pickup coil. As the vacuum advanced worked back and forth, the two wires were always moving and over time could break. This would shut down the engine pretty fast, but most of the time-out restart.

What brand of ignition module do you have?

Example of how to wire HEI,
12 gauge wire off battery terminal to connector #30 on a 40/50 amp Bosch style relay, 12 gauge wire from connector #87 to HEI.
Key switch ( + ) wire to relay connector 85, relay connector 86 to a solid chassis ground connection.

You can use the power feed off the amp gauge if it's easier to get to get to for the 12 gauge feed wire, but the Amp gauge wires must be 12 gauge or bigger.

The location of the ignition module does not make them hot, it's the amp draw. The Aluminum housings were heat-sinks used to pull heat away from the modules along with special thermally-conductive-grease.

Yes, my hei module is about 4 years old, maybe 3000 miles on it, was a NOS ACDelco, D-1959 if I recall, installed with the provided grease. I do have a spare.
I have the 50a relay fed #10 wire from starter terminal & #10 to square coil.
I will pop the dizzy cap and survey the internal wires, and review all wires which were new when installed 4 years ago. My truck lives indoors so wiring has an easier life. On edit: my reluctor died a bout 1.5 yrs ago so that is relatively new.
When I first installed the Langdon I had a stumble i could not cure, putting the old dist back in no stumble, so I changed out the module and all was fine, until now. If I am going to change the module (which I will) I’m inclined to follow Jerry’s lead and relocate it to the cab.
He recommended multimeter probe type wire, curious if 18awg is appropriate, bigger is not always better.

Chuck

Looks to have plenty of wire to it, and those bigger amp relays don't go out very often, so thats good. Changing the module if already have one is a bet, keep the other as spare just to get off the road if need be. If you relocate the module, make sure its on a heat-sink of some kind and protect the wires good. Probe type wire is very flexible and can take more vibrations easier. These guys are good to deal with and can help you out, https://ceautoelectricsupply.com/products/

These kind of problems are really hard to fix, sometimes you need it to stay dead long enough find out why.

I’m tempted to wire a temporary bypass switch on the relay to basically Hotwire the truck, if it dies I can then flip the switch manually to see if key or relay are the fault.

Chuck

I just bought some extra flexible wire for another project from Amazon. That might be something you might look into if you find issues with the wires flexing. LINK

I was looking at that specific wire yesterday, along with this heat sink which has closely spaced fins.

https://www.amazon.com/Awxlumv-Heatsink-Amplifier-Transistor-Semiconductor/dp/B07THL4LYN?th=1

There is an old school electronics store in San Rafael I want to visit, especially want to find the male/female crimp ends that fit the module correctly.

Chuck

Here is a HEI voltage supply question:
The engine cut out after a series of stop/go city traffic and after a especially few long idle/ move 100’ long idle sequences.. Is a possible drop in voltage to the HEI might cause above referenced cutout scenario?
I ask this because in hindsight last week I felt the engine kind of miss a tick at idle and my foot applied the gas pedal enough to “catch” the stumble.

My generator and battery came to me with the truck which I have had 7+ years now. The truck typically does show a + on the stock dash Guage right after starting and as stated the 12v battery is strong enough at the cutout situ to spin the 6 v starter over seemingly like normal.
Me and the truck are not near my shop for a few weeks and I will run up there to grab my meters today and start taking readings and monitoring outputs and settings.
But this is a don’t know what I don’t know situation, and while I can take readings I don’t necessarily expect to see anything unusual.

Chuck

My suggestion on using high flex wire was intended to apply to the point type distributor, to replace the wire from the coil to the distributor housing- - - - -the one that's constantly being flexed when the vacuum advance moves the housing all the time. The only wires in a HEI system that do that are the ones between the pickup coil and the module, and GM has already used the right kind of wire there.

My suggestion about relocating the module to a heat sink inside the cab applies to conversion jobs that put the reluctor and pickup coil into an original equipment stovebolt distributor housing. It would be a good idea to extend the pickup coil leads with high flex wire to a junction box mounted near the distributor housing, since the original style vacuum advance would still be used in that application.
Jerry

You said your battery is 7 years old. I would have that load tested. Sometimes they'll show full charge but there could still be a problem inside. Do you keep your battery on a battery tender all the time when not in use? Because it's very rare for a battery to last that long these days unless it is on a tender most of the time

Thanks Jerry, that saves me much effort for no gain.

As for the battery, minimum 7 years….never been on a tender, and the truck does sit a lot in wetter months (winter, we don’t have winter, just shorter days and some rain) sometimes 2 months and it has always just been there.
It is a situation where I would just say thank you for your service when I replace it. I will follow up on a load test.

Chuck