Engine dies while driving / restart...drive, repeat

[7T1240]

This past Saturday I got to drive my Z (1971 240-Z) a fair bit. During the winter I try and pick a clear day with dry roads to give the car some exercise about once a month. I drove about 30 miles at highway speeds, then another 5 in city traffic.

I shut the car down for about 15 minutes, then went back to it to resume errands. It started just fine, I pulled into traffic in first, then second...than a loss of power. I coasted into a parking lot, popped the hood and checked for loose wires (didn't see any). Got back in and turned it over, and it started. Drove about 2 more miles and the same thing happened again, and again I pulled to a stop, hit the starter, and off it went again.

About 1/2 mile farther down the road, at about 30 mph, it died again. This time, I took the car out of gear, pressed in the clutch, and hit the ignition. It started, but it also gave a loud backfire.

I'm not the greatest at troubleshooting and diagnosis. My first inclination is to suspect something electrical. I have done the 280ZX / E12-80 dist. swap, and I thought maybe the module was unhappy, or one of my heat shrink solder connections for the distributor wiring is loose.

This is probably the longest time I have driven the car in the past 4 months or so, and it was up to full operating temp.

Anyone have a direction to point me in for troubleshooting?

Thanks, Gary S.

[FastWoman]

Was it a backfire (out the intake) or an afterfire (out the exhaust)? If it was a backfire, you might be having fuel starvation issues. Does the engine die very suddenly, or does it sputter briefly before dying?

If it was an afterfire, you might have ignition problems. If the engine is running, and the ignition very briefly drops out, the exhaust will fill with raw gas fumes and oxygen. Then when the ignition kicks back in with the engine still spinning, the first load of hot exhaust gas (and flames) ejected into the exhaust will ignite the raw fuel and air.

[Bruce Palmer]

I would guess "unhappy" module. Take it off the disrtributor and clean behind it so is isn't contacting the distributor body. Don't recall where I heard that but it was on the internet so it must be the pure quill....

I had a Maxima that had an "unhappy" module that was very sensitive to heat but by the time I'd pull into a lot and raise the hood it would have cooled down enough to start again.

Just for grins, you might pull the float bowl lids and see if you have any accumulated beads of water rolling around on the bottoms of your float bowls. Another old wives tale that a bead of water can plug the outlet.

[7T1240]

Sarah and Bruce, thanks for your replies.

Was it a backfire (out the intake) or an afterfire (out the exhaust)? If it was a backfire, you might be having fuel starvation issues.

Don't know for sure. I do remember it sounding like it came from the engine bay as opposed to the exhaust, and thinking "ouch, that can't be good for the rings on that cylinder".

Does the engine die very suddenly, or does it sputter briefly before dying?

Suddenly, no sputtering.

I would guess "unhappy" module. Take it off the disrtributor and clean behind it so is isn't contacting the distributor body. Don't recall where I heard that but it was on the internet so it must be the pure quill....

Should be clean back there, recently installed and not too many miles since. But worth a check.

I had a Maxima that had an "unhappy" module that was very sensitive to heat but by the time I'd pull into a lot and raise the hood it would have cooled down enough to start again.

Wow, that really is sensitive...and frustrating!

Gary S.