Hi
I have an 85 4+3 z-51 with some mods.The car is good and pulls quite good.
In the morning it starts immediately and is normal with respect to idle and driving.
Then it comes to the problem: The car has normal driving temp. If I accidentally have stalled the engine because of too little throttle when engaging the clutch it sometimes (1 in 50 starts) it do not start.
The symptom is the following:
The car has been driving for a while and has normal engine temp of about 185 degrees ( I have 185 degrees thermostat).
Battery is fully charged and relatively new.
The lights on the instrument cluster is normal
There is no dimming of the lights of the cluster when using the key to start and no clicking of any relays.
The clutch is pressed down to the floor and the gearstick is in reverse or neutral all after.

I tighten the ground cable on the battery and then it starts as it was new. This happens 100% of the times when this problem occurs.The battery cable looks very good, theconnections on the cable and the battery is super clean. What is strange is that I only have to release the nut on the cable some few degrees and then tighten without moving the cable. There should is for me no logical explanation for this to happen as it seems that the starter is ok, the cable is ok and the battery is new due to the same problem.
I have no VAT system on the 85.
I had the problem now yesterday. It was only that I stopped five minutes to buy something and when I tried to start it showed the same symptoms. I just turn the ground cable nut a degree or so and it started like a god.

Can anybody help or have some recommendation. The car has only gone 65k

If it was the ignition key why then start when tightening the ground cable nut. The grounding of the cable itself measures that it has good ground connection.

It is annoyint because this happens always when it shouldn't for ex. in the city or in the rushhour or other unpleasant places (Murphys Law)

Would appreciate any help or recommendation

Jan-Erik

 

sounds like one of a couple of things... and the ground cable is one of them... first off, the ground cable may be working loose... try some threadlock? just an idea.

perhaps some corrosion has build up on the face of the cable end, try cleaning it off. Also, find the other end of the ground and clean it up, too.

Check the starter connections, they should be clean.

my final thought is with the starter itself.

 

Thanks for the info. I will try the threadlock

The surface of the battery pole is shining clean and so is the batterycable.


What can it be with the starter that is solved by the battery pole tightening in this case?

Just some question.
Why would the lights on the instrumentcluster be normal if there was a bad connection to the ground cable??
If there was some corrosion and the voltage drop would be too large why would not the luster lighting drop??
The problem is unambigiously solved by tightening the groundcable screw. I have taken away some of the rubber insulation so there is good metallic connection between the cable and the battery pole.
When this happens it seems like there is a good and tight connection between the cable and the battery pole.
I agree that it sounds like a bad connection. I cannot see what it can be with the starter when it is allright after tightening the cable at the battery and nothing is touched nearby the starter.
I thought first it was corrosion that made a voltage drop so that the ECM recognized it as a too low voltage to start the engine, but the Forum said that the ECM does not read the voltage in the starting process.

Well, any other recommendations?? Please!

 

If you can effect a 100% fix by turning the neg post bolt, then that is where your problem is. The next time it won't crank, have someone wiggle the neg cable while you hit the starter. If it cranks or cranks intermittently, then you have a bad connection from the neg cable to its lug. You might also have a broken connection in the battery to the neg post, new battery or not! I also recommend that you do not use locktite on the battery bolt as this greatly increases the torque required to loosen the battery bolt and could cause the battery post to break and rotate. Locktite is an insulator and you want all the connecting surface you can get between the cable and the battery post.
Also, the next time it won't crank, measure the battery terminal voltage while you attempt a crank. The voltage must not fall below 9.0 volts or the battery is discharged or at the end of its life, new or not!