81 SC dying at speed

[Bob Ashlock]

Sorry to hi-jack, but just to give a little more insight about what was described in the post above by Tony, there are 6 flat beryllium copper "tabs" that connect the actual connector to the pc-board. One of those provides the ground signal 31/1, marked on the board. From years of use, and fast 60A discharge current pulses, and of course depending on humidity, electrolysis and erosion of the metal occurs. Eventually the 'tab' becomes so thin that it develops a small crack and eventually separates at mid-point. When the unit is cold, or vibration allows, electrical contact can still be there, but with any change, usually heat, the gap widens a little and continuity is lost. So a unit "can" work, sometimes, and other times not. This is one of the common failures of the 6-pin unit, a somewhat easy fix in itself, but while in there a complete service makes good sense. The green arrow in the upper right area of the photo shows the 31/1 connection 'tab'. This particular tab is in very good shape. I did not have a good photo of an eroded one handy. But imagine that tab looking all crusty with a little crack right across the middle and you will get the idea.

[timmy2]

Originally Posted by hughc

I am experiencing a problem somewhat similar to mzavada and I eliminated the possiblity of the fuel pump by removing the FP relay and using a jumper wire to keep it energized.
When the vehicle quit at speed I just coasted to a stop and did not touch the key.
I checked and the FP was still operating which would leave me to believe my problem is electrical (ignition).
But I've yet to find the solution.

Hugh, I know you said your CDI was rebuilt by Bob Ashlock a few years ago. Have you reached out to him to see if he can loan you a test unit to confirm the CDI is not the problem?
Your post about the CDI:
How to test rev limiter on SC (CIS)

[hughc]

I've corresponded with Bob but only because I tried using the 2nd CDI box I have ( his loaner, which I purchased from him after he had repaired mine) and the car wouldn't even start.
Bob reminded me that the loaner WAS working fine when I used it untill mine was returned to me.
At the time I didn't mess with it any more and just re-installed my current one.
So I'm back to square one.
I will re-try my loaner but I'm at the moment trying to get the timing set to spec.
Hopefully by tomorrow I'll have the timing set as I want it.
( My friend has a proper timing light so I am at his mercy as to when he can spare the time to do it).
While we're at it I must explain that I tugged at the green coax very close to the distributor and the engine quit. That prompted me to pull the distributor to have a closer look at the connector. Hence the reason why I'm messing with the timming.
Nothing obvious there unless there's a somewhat week connection at the two pins inside the distributor. Not sure what I have to do to check that out completely.
There may be something there to consider as the engine quitting problem was there before I renewed the green wire and of course its still there.
So my current plan ( since I'm running out of ideas) is to get the timing right then try once more tugging at the green wire, close to the distributor to see once more if the engine will quit.
At some point I'll also try my spare CDI box, again, to see what sort of results I get.
Very frustrating and discouraging.

[timmy2]

Is your new green wire made by Bosch or URO?
The early URO ones had a loose female connector “shoe” problem where they go into the dizzy.
Solved by pinching the female terminals tighter on the sides and a little on top.

[hughc]

It is a URO and at the time I did look at what you are suggesting but since both female connectors are in the plastic housing I couldn't see how to do it without mashing every thing up.
I can be somewhat ham fisted at times.
I thought of removing both female connectors from the plastic housing but I'm not well equipped to do that either

[timmy2]

A small jeweler’s screwdriver will fit in on the sides and can apply enough force to adjust the shoe width and height. Or just pay $72 for an original one...

[hughc]

Thx Dennis, I tried with a small jeweler's screw driver but was afraid of fracturing the plastic holder.
I'll try pulling on it again and if it causes the engine to quit then I'll have to deal with it one way or the other.
I'll get the timing sorted first before I do anything.

[hughc]

Well guys, some good news and bad news. I went for a 800 mi drive last weekend and the car ran flawlessly. It didn't quit once. I really enjoyed the ride even if I was always concerned that it might quit at any time.
The bad news? I have no idea why it ran without quitting as it had been, and that's a mistery. There was nothing done since my last post other than re-installing the green wire plug into the distributor, adding a few drops of oil on the distributor felt (and since it was freshly rebuilt last fall it should have been ok but it looked dry) and re-installed the distributor. I didn't even take the time to check the timing but I knew I was very close. I will check it to see what I have and make a note of it for reference.
I had the jumper wire in place all week-end and have since added the FP relay but I've pretty well concluded that the FP was not the problem.
Sorry I can't tell you what has change to make better and I probably just shot myself in the foot for talking about it.
We'll see how it goes from here on in.

[timmy2]

Maybe the green wire is better seated. Just pushing a little on the contacts may have done the trick.

[hughc]

Originally Posted by timmy2

Maybe the green wire is better seated. Just pushing a little on the contacts may have done the trick.

I certainly hope you are right on that one
Time will tell.

[timmy2]

Definitely a good heat soak on the 800 mile trip. Should have moved the metal contacts around enough to cause the problem if they weren’t seated well.
As you said “Time will tell”

[hughc]

I want to thank all those that assisted with suggestions while troubleshooting that quitting problem. (Dennis Tim, Tony etc )

No doubt I'll be back with more questions

Hugh

[Iceguy]

I was having mzavada's problem a year ago with my '80 SC. It would cut out -- just shut down -- as I drove. At first I would put the clutch in and pull over. After a while I would try to restart it and it would fire up and away I'd drive. Eventually, I got tired of pulling over and waiting, so I left the clutch in. It would fire up and go after 10 seconds or so! Finally it dawned on me that I had had this problem with my mother's 60's era Buick Special. In the end that turned out to be a dirty, partially clogged fuel filter. When I replaced the fuel filter in my SC, all was well. I've not had the problem since.