Trouble shooting motor just died

[duke46]

I thought I would ask you guys for a little help even though I am working on my 72 Corvette stock 350 with direct tach drive. And only 120,000 miles on her.

Was having a small aggregating miss and saw it today fire jumping the insulator on one plug.

But here is what happened. We got in the car after I took it for a test drive. We made it out of our drive and coasted into the next one and it would not start back up. Riding mower and chain and a friend then down to my shop. Thought the fuel pump had quite, It is the org one. Disconnected the gas line and it filled a bottle up ASAP. Connected the line back and it fired right up. The little brass filter also looked fine. So just drove it to my garage a parked it.

Today I wanted to see if I could find a reason for the cause. It has been in my garage for 5 months but fired up like is always has. That is when I saw the arc on the one plug.

The tach drive dist is an oem one but I used the electronic ign kit to replace the points. Best thing I have ever done because it could set for a year before starting and you know what has to be done to points 99% of the time before you can fire up.

All the wires to the coil look fine and from it to the dist look good and all is tight.

So what just made it shut down and not restart till a couple of days latter?

Sure hard to fix something that is not broke GRRRRRRRR It is like something shorted out and killed the fire. These motors come with the chrome wire covers along with the chrome dist cover and that cover is off right now. Was the cause in that area maybe? I know they do not come on trucks but thought I would just ask for maybe a little trouble shooting help on here and see what some of you might advise.
Thanks

[Sicklajoie]

Did you replace the ignition module? It doesn't hurt to try something simple first.

[WorkinLonghorn]

I agree ^^^.

I had one of those ignition kits and left the ignition in the "run" position by mistake while I was on a short job. When I returned the unit was toast. I heard they ( Pertronix) fixed that weakness in later models though.

I would take a wire off a plug and put it on a spare plug and hold it to a ground and crank the motor and watch the plug for a crisp blue spark.

"saw it today fire jumping the insulator on one plug."

If you are seeing spark jumping around then I think your wires are crap or you need to clean and inspect the plugs and area around them.

If your spark is sub-par you need to find the reason, ie. low voltage into the Distrib, bad or dirty connections, crappy oil soaked, burnt, cracked wires, bad module, cap, rotor etc. -WL

Also replace that old fuel filter.

[duke46]

Talk about being slow to fix something then I guess that would be me.

And old friend dropped in to see us on the 4th and I was showing him the cars and told him what happened to the Vette. He looked at the carb and ask me if it had the brass filter in it and I said yep. He then told me that over the years of running that type of carb with the brass filter that on more than one occasion his motor had just shut off. He then told me that just one drop of moisture would just stop gas from going through it.

I told that to another older vette guy and he said yep it sure would. And he had told guys in the past to always keep the tanks full and then you would not have to worry about condensation all that much. Also keeps you tank from rusting and is what I tell all the motorcycle guys.

When my car cut off and would not fire back up we took it to my shop and a few days latter after I had bought a new pump my friend and I started checking it out. I didn't try to start it up but now wish I had. What we did was remove the fuel line and check for gas flow and had plenty and then I took the brass filter out and blew it out good even though it was clean as a pin. One all was put back together the car fired right up and then I just put it back in my garage.

I am guessing that if I had an external paper filter or even the paper one that would replace the brass oem type that if water was the cause then they would have not caused this type of problem. I will put in some dryer in my tank or some 99/100 alc just in case this was the problem. My car stays in a wood garage and have never seen any moisture form in my 24x50 space as long as I keep the doors close. But try to keep at least 1/2 or more gas in it. Might only drive it a couple of times a year but it has never let me down and never had a problem like this even when it was keep in my shop that is a steel building and every thing in it when the weather is just right will sweat and even seen it so bad that you thought it was raining in there with so much water dripping off the metal roof. But never had any problems before and for sure under those conditions that should have happened before is water was the cause.

It is starting up just fine and did find one plug that was arching and some of the others were gummed up a little so now to test drive it and see how it does.

Have any of you heard about the water and the brass filter before?

[Mrturner1]

Originally Posted by WorkinLonghorn

Also replace that old fuel filter.

Good call 👍

[68gmsee]

Originally Posted by duke46

...
Have any of you heard about the water and the brass filter before?

I never have. However, moisture in the alcohol/gasoline is a problem and even though you don't see any condensation inside your garage there is still moisture in the air. Ethanol/gasoline is almost like a sponge in attracting water molecules.

Here's a demo video I saw. It's a little exaggerated but it gives you an idea.
https://www.youtube.com/watch?v=YeCyFxoWPpo

[duke46]

Thanks 68 that was interesting and also now I know why most all marine places that sale gas have the one that does not have that crap in it but really hits your pocket for sure. We have a couple of stations here that also sales it. I use it in my late sons custom Shovelhead motorcycle.

What I found yesterday that really has be confused when I looked in the gas tank I saw like a clear film around the neck and it was all wrinkled up. I managed to get most of it out of the neck. I will use one of my vacuums to get any of what is left but makes me wonder if there is also some in the top of the tank? Gas looked fine and the sock strainer looked okay and noting laying around it. I did see something I didn't like on the back wall around the seam of the tank. I will let my old friend look at it today and see what he has to say.

You would almost think I used a sealer in it but if I did it was so many years ago that I have forgot about it. I just don't remember dropping the tank when I did the restoration on it. It set for many years and had the old good type gas in it but when I went to fire it up it had none. Yep a small rust hole in the bottom corner had drained it. That was kind of good because I didn't have to deal with any old gas. I fixed the hole is about all I remember but didn't remove the tank. It looked nice an clean. I have used sealers on a couple of tanks in the past but years after I finished it. Looks like I may be removing the tank and giving it a good cleaning job. But then what do I do???? Could fill it up with the ethanol free gas I guess? Almost makes me wish I could just drain the tank when I know it would not be driven for a while. At least they do not hold a lot of gas. Even if I did seal the tank then I still would not want the crap gas in it like we have today but could use the stabilizers and That I do use.

Got any good ideas guys?