'79 SC dies at road speed

[rds]

Driving along at 55 and the engine stops. It doesn't sputter like out of gas it stops. I put the clutch in and restart and off we go another mile and does it again. 3 times till I come to a stop. Then it cuts out and doesn't restart. 10 times I turn the key and it vroom and doesn't start.
I wait 20 mins and it starts like normal.
I changed the fuel filter and accumulator. What next?
It feels electrical...? Everything seems tight? Is there something obvious I'm overlooking

[Bob Kontak]

Do you have an old Permatune rather than a Bosch Capacitive discharge box?

I can post a picture of one of my two dead ones if needed.

20 minutes is about right for it to cool down.

[rds]

All I see at Pelican is Plasma tronics. Can you post a picture please? thanks

[Targalid]

Next time this happens verify that you do not have spark by placing a good spark plug into one of your spark plug wires, ground it against the case and have your assistant turn the key. If you verify no spark as the cause of engine failure, work back from the spark plug to the distributor, the coil and the CDI.

[Mark Salvetti]

Sounds a lot like the intermittent cutout of my '79 SC when the rev limiter relay failed. The SC prevents over-reving by shutting down the fuel pump. I had found a cut wire in the fuel pump relay circuit at the fuse box. I soldered it back together and everything seemed fine at first, but then it started to intermittently quit running and not restart until it sat for a while.

When the car fails to restart, does the fuel pump run? If not, the rev limiter relay is a small black box bolted to the body behind the fuel gauge. Try disconnecting the wire connector to it.

Mark

[rds]

Thanks Mark, I smell fuel when I'm turning the key and was worried about flooding it. It feels like the CD box or coil?

[Bob Kontak]

Originally Posted by rds

All I see at Pelican is Plasma tronics. Can you post a picture please? thanks

This is old Permatune. Do you know where your CDI is?

[wwest]

This is a common system of battery overcharging....

If so then you have to turn the key COMPLETELY OFF for a slow count of 10 to restart.

In my case a bump in the road would cause the tach to jump, rev limiter would shut down the fuel and hold that way until power is removed from the rev limiter for ~10 seconds.

Another symptom is e-brake light remaining on.

Secondary effect is CDI overheating and needing to be cooled to restart.

Garden hose fine spray to cool the CDI works as a diagnostic.

[wwest]

Originally Posted by Mark Salvetti

Sounds a lot like the intermittent cutout of my '79 SC when the rev limiter relay failed. The SC prevents over-reving by shutting down the fuel pump. I had found a cut wire in the fuel pump relay circuit at the fuse box. I soldered it back together and everything seemed fine at first, but then it started to intermittently quit running and not restart until it sat for a while.

When the car fails to restart, does the fuel pump run? If not, the rev limiter relay is a small black box bolted to the body behind the fuel gauge. Try disconnecting the wire connector to it.

Mark

The rev limiter is HIGHLY subject to latch up due to battery overcharge, tach jumps, rev limiter sees a few sparks to close together, opens fuel pump relay.....

[4flyboy]

Years ago on a road trip to Las Vegas I had similar symptoms .....at speed the engine would cut out as if someone were throwing a light switch.

Limped into Baker at 5 pm on a Friday afternoon, everything closing down. An old guy with a garage and a junked VW bug behind his shop took one listen to my plight....muttered coil wire and disappeared behind his garage.

I was less than enthusiastic.

He plugged in a ratty old coil wire from the bug and it ran faultlessly....... $5 and 10 minutes

[rds]

Yes, mine is a Bosch

[Bob Kontak]

Originally Posted by rds

Yes, mine is a Bosch

See wwest post on spraying the CD box with water. Bring a spritz bottle with you to see if the turnaround time is shorter.

[Bob Kontak]

Originally Posted by 4flyboy

He plugged in a ratty old coil wire from the bug and it ran faultlessly....... $5 and 10 minutes

Good input.

To test, you can buy an el-cheap-o 1967 camaro coil for under $20 and the shortest e-cheap-o coil wire for $6 and put those variables to bed.

Then put decent stuff on.

[stormcrow]

I had a similar problem with my P-car - would be driving down the highway and it would just cut off. Turned the ignition off engaged the clutch turned the ignition back on to start it - loud bang out the exhaust.

What I found out was that the terminal posts on the distributor was just touching the edge of the posts on the distributor cap.

Pulled the distributor and installed new shims put everything back together and never had a problem since.

What was interesting is it wouldn't happen all the time - when on a trip to Pa it cut off about 15 miles down the road and not again to around 200 miles. Annoying and always in the back of my mind waiting for it to happen again.

Since the fix problem solved.

[rds]

Still having issues.
I replaced the accumulator and fuel filter. Runs fine then 3 minutes later at idle speed it just stops.
Im wondering if its the fuel pump now.
"It just stops, then restarts right up"??????????
What else could it be?

[Hoss911sc]

It's possible it's worn contacts in the ignition switch if it restarts after turning key off/on. Had a similar intermittent stall like a clean cut-off because it was actually switching off the ignition randomly. The electronic part of the switch is annoying to replace but not too bad - just difficult to get to if you're not flexible any more ..

[tirwin]

Originally Posted by rds

Still having issues.
I replaced the accumulator and fuel filter. Runs fine then 3 minutes later at idle speed it just stops.
Im wondering if its the fuel pump now.
"It just stops, then restarts right up"??????????
What else could it be?

Did you verify the battery is not overcharging?

What you are describing is a classic symptom of a CDI box on it's last legs. It dies when hot and then works again once cooled off.

[rds]

Thanks everyone who contributed.
After all was said and done, I had the car taken to the dealer who , after 2 hrs of tech time, diagnosed the issue as a fuel pump relay. As expected, the relay was intermittent and wasn't doing it all the time so the fuel pump cut out.
After all that, I now have a new CD box, fuel pump, filter and accumulator. all's good, funning like a champ. Happy Shiftin'!!

[ItzaMe]

Originally Posted by rds

Thanks everyone who contributed.
After all was said and done, I had the car taken to the dealer who , after 2 hrs of tech time, diagnosed the issue as a fuel pump relay. As expected, the relay was intermittent and wasn't doing it all the time so the fuel pump cut out.
After all that, I now have a new CD box, fuel pump, filter and accumulator. all's good, funning like a champ. Happy Shiftin'!!

I have this exact same issue happening with my car right now. I was driving down the road and it cut off and isn't starting anymore, only cranking. When you turned your key to the 'on' position do you here the fuel pump make any noise? My fuel pump area makes a vibrating noise, it doesn't seem to be filling with fuel in the filter but it seems to be working correctly. I had my electrician check the CD box and said there is power running through it but its not igniting the coils. Don't want to buy a new CD box if my current permatune is alright.

[MattTHEpainter]

Originally Posted by ItzaMe

I have this exact same issue happening with my car right now. I was driving down the road and it cut off and isn't starting anymore, only cranking. When you turned your key to the 'on' position do you here the fuel pump make any noise? My fuel pump area makes a vibrating noise, it doesn't seem to be filling with fuel in the filter but it seems to be working correctly. I had my electrician check the CD box and said there is power running through it but its not igniting the coils. Don't want to buy a new CD box if my current permatune is alright.

What year car?