78 sc stopped while driving?
 

Was out and about, car had been running very well. Started her up this afternoon and was out for a ride and she cut out all of the sudden.

The fuel pump has been noises, but was tested last week and pulled 8.8 amps.

While driving this afternoon I heard what can best be described as electronic interference, not terribly loud, but there. It ran for about 20 minutes before cutting off.

I could get it to start again after a few minutes, but as soon as it dropped to a steady idle it stalled.

Ince I got it started again I kept revs above 3500 and had it running for about 10 seconds until it cut off again.

Any ideas? Fuel pump?

Sounds like a lack of fuel. You could use a can of starter fluid to see if you can keep it running by adding fuel.

If it sputters at all before it dies I buy into fuel. Kill this variable. Find the round relay closest to the driver in the front trunk. Should be red. Pull it out and spread the male pins a wee bit with a single edged razor blade or even a small sharp wood chisel. Has to be sharp enough for the tip to enter the gaps. Don't go nuts - just a few thousandths of an inch will do it. Push it in and out of the socket a few times to "rough" it up.

If it's a hard shut down then maybe the CD unit. Is it and old (silver box) Permatune? They can fail, cool down then run.

8.8 is ok on the fuel pump. Believe 6 is brand new. 10-12 is pretty tired.

No sputter at all. Just a shut down. Ill check fuses. Was running perfect up until it cut out.

Blown fuses will not allow a restart.

When my Permatune(s) went bad it was instant engine death.

Do you have a Bosch CDI, a Permatune or other?

Just asking - not sure it is your problem.

A sudden cut off makes me think electrical over fuel.

When my Permatune died the car wouldn't start again after sitting parked for about an hour. Thought it was FP relay so I swapped it with the spare. It started so I thought I fixed it. About 2-3 miles down the road it died again for good. Just cut off completely.

Hey Tim,

FWIW - When mine died it was in the 20 minutes to an hour range before re-start.

Cd or coil.

8 amps is about right but volume and pressure are important.
my fuel pump made noises the entire 10yrs i owned my 911.

if it does it again check for spark.
when it goets hot and cuts off, then cools and will run that is ignition.
i would start with a $50 MSD coil from advance.

My Permatune went just as Bob's did. It worked then it didn't. Just like that.

Quick update- I can get it started for about 2-3 seconds then it just stops. No sputtering, just a stop. its starting quicker this am then last night when it was warm. Its in the garage, so there is a strong smell of gas. Unburnt gas.

Im a basic mechanic at best, so i'm not understanding that I can get a spark, but not hold one. maybe distributor issue? perhaps replace the cap?

make sure you have gas. when it is out of gas, it will do that.

when it will not start:
if you have a timing light you can connect it to any one of the plugs wires and while someone cranks it, check to see if it flashes.
or connect a spark plug to on eof the wires and ground the plug to metal and start it.

with the key on, remove the air filter and lift the sensor plate. you should hear the injectors squeal as fuel is injected. try to start it. this dumps fuel into the cylinder so do not do it too long befors starting.

Make sure you have fuel.

Read the post above from T77911S, VERY good information!



Open the hood in back. On the driver's side (left) firewall above and near the rear of the car will be your electronic ignition. It is near the fuse panel.

Look at the box. Note the color of the unit.

Does the box say Bosch, Permatune, MSD, or something else?

This is a VERY likely culprit of your symptoms. IF you have a Permatune (better known as Perm-A-Junk) and it is SILVER you will want to look into replacing it. Bench test your coil. My Perm-A-Junk fried two coils before I was able to replace it. The unit tested and STILL bench tests as good but I will NOT trust it.


It is also good to check out your distributor cap and rotor. Are they in good repair? You can take a good felt tip highlighter (I like using the big chisel points) and run it on the inside of your distributor cap. If there is a crack the tip will get slightly stuck and the ink will start filling in the crack. Do not use a permanent marker, the highlighter will just wipe away. If cracked, replace the distributor cap. You can do the same with the rotor. Clean/polish the terminals inside with emory paper if they are dirty. Not trying to remove material just the corrosion from the electrical current.


The relay for the fuel pump is a round one and should be RED in colour. It is in the trunk (front of the car) on the driver's side near the brake fluid reservoir. There should be a cover on it, it is long and thin. In a pinch you can use the A/C or other non-essential relay in the place of your fuel relay. If you do not have a RED one in place, please get it and put it in.

Got her running again....Thanks for all the help.

Here's the final diagnosis: Probably fuel- Although the gauge read a half of a tank, I now know I have a gauge problem.

Stangely though, the plug to the ignition coil was nearly off as well. That may have contributed to it. There was some corrosion on the distributor cap as well. Luckily I got a new cap from Pelican a few weeks ago in anticipation of having to replace (this car is only a month old to me...)

So in addition to some not so great ignition parts, or dirty ones at least, fuel seems to be the most likely culprit.

On a bright side, I did most of the tests listed here and found out a good bit about my ignition system! Thank you all for all the information. I was sweating this one!

was the light on on the fuel guage ? trust the light not the guage..

Sounds like if it happens again you have a good base knowledge to work with ..

My initial question would have been " what colour is your coil ? "

The light was on- I was on my way to get the 90 rec fuel that doesn't contain ethanol. Its some ways away. I thought I had plenty of gas at half a tank.....in fact I usually top it off once it gets to half. It shows full but does't go below half evidently.

lol a common issue .. you need a sender ..

in hindsight im sure when you saw the light come on you went hmmm.. i wonder if i really do have half a tank ... then when the car stops .....

You don't need a new sender.
Just remember half means empty.

The fuel senders are crap.
I just replaced mine and it said I used 1/4 tank of gas in 20-30 miles.

Artificially cool the CDI, garden hose water trickle, see if that works.

Component heating in the CDI resulting from past/current alternator/VR intermittent overvoltage.

DO NOT pour water on your CDI.
If you want to artificially cool something use freeze spray, available at most electronics stores.

I like a compromise. Maybe just spritz water on it with a spray bottle.

A little silicone spray near the connector would minimize risk of water creeping in.

Never did it. Just talking.