sclemow wrote:It's been very reluctant, even in the summer, so I don't think it's simply damp and cold weather.
rich@minispares.com wrote:my car was doing this - getting worse and worse to start, it was the engine earth strap
If it struggles in the summer, it sounds like a battery wiring issue to me.
You can check for voltage loss to the starter like this:
Firstly, make sure the battery is good and fully charged.
Get a voltmeter and connect it between the engine/earth and the feed tag to
the starter motor.
Crank the engine over.
We are looking for 12 volts under load, and if there is an appreciable drop
here we need to work out which side of the circuit to investigate. That is,
do we have a bad earth, or a bad feed?
The concept is the same for +ve earth and -ve earth, but I'll use -ve as an example.
Get your voltmeter and a long piece of wire, an assistant would be handy.
Now, a voltmeter actually measures "potential difference" in volts and we
normally use it to check that the PD/Voltage is between a feed and the earth,
like we did in the first test.
What we will be doing here is to use the meter to measure the "Potential Difference"
or "Voltage Drop" from two points on firstly the negative side of the circuit, then the
positive. It may sound odd connecting it to two negatives or two positives, but trust me
here, we are measuring a "potential difference"...
Have your assistant hold one end of the long wire DIRECTLY on the negative terminal
of the battery, not the wiring tag, the actual stub on the battery.
Connect the other end of the cable to one side of your meter.
Set the meter to a low voltage scale, say 12v.
Using the normal test lead in the other side of the meter, connect this to the
engine as close to the starter motor as possible.
So now we have both sides of the meter connected to -ve, one at the back of the car,
and the other at the front. You should have a reading of Zero Volts.
Now, crank the engine over and watch your meter: If it moves negative, swap the leads
round on the meter and try again.
If you get a small reading, try changing to a lower voltage scale.
Crank the engine again....
The reading will show you how many volts you have "lost" in the -ve side of the circuit.
Now the other side....
Have your assistant hold the long wire on the positive side of the battery.
Connect this to one side of your meter.
Connect the other side of the meter to the starter-motor main feed tag.
Spin the engine over (swapping the leads and/or adjusting the scale as above if necessary)
The reading will show you how many volts you have "lost" in the +ve side of the circuit.
The concept remains the same here for wherever you connect you meter, for example,
at the front end, connect the short lead, before, then after the solenoid. If the loss happens
at the output of the solenoid, but not before, this component is suspect...
As I have said in another post, because so many of the cables (read, virtually all of them)
are only crimped, it is possible to get a bad connection between the cable/braid and the tag.
This is why I always solder ALL my battery leads.
If you lose a bit in each side, like rich says, you can end up with severe coil-robbing and
either a very weak or no spark.
Good Luck,
Ian
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