HELP !! 72 gs 350 shuts off abruptly

[Guest]

My 72 gs 350 will be running down the road great when all of a sudden it feels like someone has reached over and shutoff the key...the car shuts off suddenly (no sputtering) . The gen light comes on and dashlights stay on if turned on during this event. If I immediately turn the key back off to on- the car will restart and run fine before doing it again. If its cooler out or at night it seems like it doesnt do it. I replaced the coil today and it still did it. I have an ignitor hei kit in the car that I am suspecting next ? Is the ignition fused somehow...is there a chance I may have an intermittent fuse ??? My inline glass fuel filter shows plenty of fuel in the line,carb runs great and is only two years old plus the car shuts off so abruptly with no sputtering that it feels like electrical / ignition problem. Any ideas would be greatly appreciated. Thanks John.

[Guest]

I had a similar problem with a Wildcat - it ended up being an intermittant contact in the ignition switch. You might check that

[Guest]

If this was my car, I would hitch up a temporary light inside car , + wired to the main feed AT the distributor/ other side of wire grounded anywhere..and go for a ride. <BR>With the car running, that light will be on. If the light remains on after the motor quits, you know the problem is in the distributor/ coil area and nowhere else.That should not be hard to find at that point. If the light shuts off, you know you have a supply problem.Then you'll have to trace it back. Jim

[Guest Teamsterdug]

I,ve never been much of a mechanic but after reading these neat little tricks offered up on this forum from time to time I'm getting so smart I may have to re-evaluate my opinion of myself. I may, some day, graduate from just a "rust picker" to a full fledged "shade tree mechanic". This sharing of knowledge is great.

[Reatta Man]

Sik GS,<P>If you are sure the problem is not in your distributor, you may want to look to the ignition contacts located on the steering column. On a '72, the electrical contacts are in a box mounted on top of the steering column, about half-way between the bottom of the dash and where the column goes through the firewall. The actual switch on the column, which takes the key, has no electrical contacts in it. When you move the switch, all it does is move a steel rod that goes into that box to close the electrical circuit and engage the starter. <P>I would check the two small bolts that hold the box to the column. Either the contacts could be dirty, the wiring harness has become partially loose or the entire box is loose. You might want to try to 'force' the problem by setting the emergency brake, starting the car and putting it in drive, reaching up and grabbing the box and harness and trying to move it with your hand. If the engine dies, you've found your problem. <P>If you DO put the car in drive (to simulate driving down the road) be careful not to nudge the accelerator pedal with your elbow. If you do, you could end up with a new doorway in your garage where you didn't plan on having one. If the contacts are dirty, try removing the harness, cleaning the harness and the contacts in the box with WD-40 or an electrical contact cleaner from Radio Shack. <P>Good luck. <P>Joe

[Guest]

Also, check the vacuum hose leading from the PVC valve to the carb base, It can look OK, but if colapses under low idle, the engine will stall.

[Guest]

my 65 gs did that !!turned out to be the ignition switch!

[Guest]

You have received some good ideas on trouble shooting here but unless you are looking right at the fuel filter when the engine quits I still wouldn’t rule out fuel. A fuel pressure gage temporarily installed is a good diagnostic idea. Also I have found debris under the needle and seat that was large enough to cause temporary blockages of the fuel path into the carburetor.<P>The bulkhead connection is another place to look for corrosion on the ignition wiring feed thru. <P><BR>Rare but possible.<BR>I have had a similar problem caused by a missing solenoid plunger return spring in the starter solenoid, it caused primary ignition grounding when the copper disc vibrated forward and shorted the 12 volt ignition bypass circuit to ground via the starters internal windings. Also check the engine wiring harness as runs along the front of the engine and down near the motor mount. If there is any chaffing of the harness wiring near the motor mount and the engine itself you could have a temporary grounding condition in that same circuit. When the engine is restarted there is enough movement to disturb the ground until it gradually works into a short again.<P>That’s probably plenty for now to look at.

[Guest]

One more place I forgot to mention is the harness connector that plugs into the ignition switch, sometimes the if we work under the dash we disturb that connector enough to become partially unplugged. At any rate if you replace the ignition switch look carefully at that connector for heat damage, you may have replace the spades inside the connector. <P>Rule 1:<BR>Don't burn down the house! Negative battery cable disconnected when working under the dash. Use a thin wire with alligator clamps as a fusible link if you need low current for trouble shooting. An inline fuse holder with clamps on each end is even better. I use a twenty amp circuit breaker installed in series for electrical trouble shooting. I also use a key warning buzzer upstream of the circuit breaker tied back to ground for an audible warning should the circuit breaker trip while tugging on wires and alike. When the buzzer stops I know the breaker has tripped.<P>Bill<P>82 455 Stage1 Skyhawk<BR>73 455 Four Speed Gran Sport<BR>70 Skylark 350<BR>64 327ci / 365hp Four Speed Corvette Convertible

[NTX5467]

My '68 LeSabre had a similar problem. It was highly intermittent too. The engine would just "die away" but I could sometimes catch it by pumping the throttle. Start times would be extended too, until it finally fired off--sometimes longer times than others. Sometimes, it ran ok, other times it took multiple times to get it to stay running.<P>There might be fuel in your inline filter, but if it isn't being pumped, it's just sitting there.<P>When I put on a new fuel pump, the engine sounded better than it ever had. I suspect the problem plagued the previous owner as the fuel line was sliced near the carb (like where a pressure gauge might be inserted).<P>It could be a chaffed wire or similar, but don't automatically rule out the fuel pump performance (flow, pressure, and volume)either.<P>Just some thoughts . . .<P>NTX5467