Starting issues

[Pomorza]

Hello all

Over the past couple of weeks I've been having a problem with starting my car. This is what occurs, when I get in the car and turn the key to start there is a delay - as in I have to wait a few moments (usually a second or two) before the starter engages. I originally thought it was key portion of the starter system (the back side of the key). That fixed the problem for a couple of weeks but now its back and is worse. This morning I got in my car and turned it over. It started once and then nothing, every time I turned the key the voltage would drop but the starter would not engage. The battery is new - about a month old - and the starter works lovely when it works (its a gear reduction one).

Does this sound like the ignition relay? I do have a few items running off the 12 volt switched that located under the dash - fuel pump, ignition, ECU, and a gauge. Could that cause issues? The car runs and drives wonderfully (minus the annoying exhaust leak - which is getting fixed this weekend) and when it does start it starts just fine. I usually don't let the starter run longer then a few seconds so I usually have to crank it twice.

Thanks

Jan

[SteveJ]

The starter is not energized via the ignition relay. You could have a solenoid going south. Measure the voltage at the solenoid while someone else turns the key. If voltage is good and the solenoid doesn't kick in, then replace at least the solenoid if not the whole starter. If the voltage fluctuates, it could be another sign of a bad solenoid. If the voltage is always low, it could be a wiring issue or ignition switch issue. You could check by having the positive wire off of the solenoid and measuring the voltage. If it's still low, it's a wiring issue or ignition switch issue.

[Zed Head]

every time I turned the key the voltage would drop but the starter would not engage.

This sounds a lot like a bad connection at the battery. Heat from resistance through a weak connection opens up the circuit, causing loss of connection and a drop in the voltmeter reading. Let go of the key, it cools down and enough current flows to get the voltmeter back. How far does the voltage drop when you turn the key?

[EuroDat]

Just to add to SteveJ's post. You can check the wiring by using a volt meter on the positive terminal on the battery and the wire that activates the solenoid. When the starter is cranking the voltage should read close to zero. If you see voltage then you have resistance causing voltage drop over the circuit.

[Pomorza]

This sounds a lot like a bad connection at the battery. Heat from resistance through a weak connection opens up the circuit, causing loss of connection and a drop in the voltmeter reading. Let go of the key, it cools down and enough current flows to get the voltmeter back. How far does the voltage drop when you turn the key?

The voltage drops to about to right below 12 volts, or about where it drops to when the starter usually engages. I do have a power wire coming off the starter that I use for a fuse box I use in the car, if that could cause issues. Its an 8 gauge wire. I could always move it if that could cause the issue I'm having. All I know is when the car is nice and warm the starter usually works right away no delay no issues. Its in the 40's here so I'm taking it needs more CCA's to get all the metal going.

Thanks

Jan

[Zed Head]

When the battery connections are bad, the voltmeter tends to drop to zero, from what I've seen. Eurodat, did you mean zero or ~11? The starter needs voltage to turn and the drop is due to amps used by the starter motor. Dropping to zero doesn't fit a working starting system, I believe.

Anyway, it does sound like your solenoid gets power but isn't making connection to drive the starter motor. If you're handy it's not too hard to take the starter apart and clean up the solenoid contact. After confirming that the solenoid is getting power.

[Pomorza]

So I measured both the voltage at the battery and the voltage going to the solenoid. According to my DMM the voltage at the battery was 12.56 and the voltage at the solenoid while turning the key was ~12.3. The car started during the afternoon without a problem. No idea, maybe my Z was just not in the mood to drive, it was Valentine's day after all

Jan

[SteveJ]

Well, your battery is good. The circuit was good, too. If it gives you problems in the future and the voltage is good, I would start questioning the health of the solenoid. If you see a lower voltage at the solenoid, I would suspect the ignition switch.

[EuroDat]

When the battery connections are bad, the voltmeter tends to drop to zero, from what I've seen. Eurodat, did you mean zero or ~11? The starter needs voltage to turn and the drop is due to amps used by the starter motor. Dropping to zero doesn't fit a working starting system, I believe.

Maybe I didnt explain it clearly. I learnt this from a mechanic in the coal mines working on belly dumpers and 789 cat rrucks. He was a bit of a bush mechanic and learnt to be a mechanic in the vietnam war.

If you use the volt meter over a terminal it will read zero until current travels through it and it has resistance (potential differance).

Example: A bad battery terminal. If you test with one probe on the battery post and one on the outside of the clamp it will read zero volts. When you start the engine its reads 3 volts. There is a resistance in the terminal connection.

You can use this method to check all the wiring including the grounds. I found a couple of my bad grounds this way. One probe on the negative post and one on the body ground connection (not the bolt, use the ring the cable is connected to). Any voltage reading while your testing the lights ground with lights on then you have resistance in the ground connection.

You can check the starter solenoid this way as well. Hold the probes on both terminals. It will read battery voltage. Get someone to start the engine. While cranking it should drop to zero voltage. An easy check for carboned contacts in the starter.

Chas

[SteveJ]

Chas was describing a good test.

If you place one lead from a meter on a wiring point that should have 12 VDC+ (such as the positive post of the battery) and you place the other lead on another wiring point that should have 12 VDC+ (such as the positive terminal of the solenoid), you should read 0 VDC on the meter. That is because the voltmeter measures a difference in potential. When the key is in the start position, there should be very little drop in potential because under ideal conditions, the wire between the battery post and solenoid does not have much resistance. If you see a voltage difference, that means that something is causing resistance in the circuit. An example of that when switch contacts are in good contact with one another. Carbon buildup can act like a resistor, and additional heating will increase resistance (as Jan described).

I'll have to add more to my electrical troubleshooting post to include more details on diagnostics with meters.

[EuroDat]

Hey steve, Gratz on your website. Looking good:cool:. I admire the effort you have put into it.

Cheers Chas

[SteveJ]

Thank you, Chas. I wanted to create a site that was informative and entertaining. I know that many people do not have a good understanding of the electrical systems in their cars, and I hope I make it easier for people to diagnose and fix their electrical systems. To borrow a phrase from an acquaintance, "It's not rocket surgery."