Irregular starting problem

[Ponyboy]

This happens every now and then: go to start the car, turn the key, and nothing happens. Battery reading starts a little above the middle line and then goes way low. Go to the engine bay and try to jump it and still nothing. But if I jump it at the battery then it starts right up. What's up?

Battery terminals are a little rusty - on my list of things to do. Advice?

 

[lemansnsx]

Originally posted by Ponyboy:
This happens every now and then: go to start the car, turn the key, and nothing happens. Battery reading starts a little above the middle line and then goes way low. Go to the engine bay and try to jump it and still nothing. But if I jump it at the battery then it starts right up. What's up?

Battery terminals are a little rusty - on my list of things to do. Advice?

Voltage drop from those terminals or a weak starter, assuming battery and charging system are in good condition. Clean 'em up!




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Andrew Henderson
The NSX Model List Page

"We have long acknowledged that enthusiasm for things automotive is a sure
sign of emotional instability if not outright dementia" - Brock Yates

 

[nsx4fun]

Intermittent starting + corroded/dirty/oxidated looking cables and terminals = first step towards diagnosis is clean those posts and cables. Odds are, that will cure it, if it doesn't, you've ruled out the most likely cause and need to look for a less obvious one.

Fritz

 

[CityofAngels]

I would check the battery terminals first. Remove the battery cables and run a little 360 grit paper over the terminals and inside the cable ends.

Also look for a fuse that may be corroded/dying.

 

[Ponyboy]

Thanks for the suggestions guys.

Cleaned the terminals and the problem is still there. I'm going to check connections from the battery tonight. The thing I don't get is that why wouldn't it jump from the fuse box terminal and only from the battery terminal?

I'll check the connections tonight and fill you guys in. Thanks.

 

[CityofAngels]

Hmmm. I have not looked for it in my car, but check the starter solenoid(wherever it is!) and see what condition it is in. If you disconnect it and check the wiring diagram in the manual or on the solenoid, you can pass 12 volts thru the correct legs and hear it click. If that is good, then connect a volt meter across the other legs while it is "clicked" and see if the resistance is pretty low. If you get nothing, it is possible the solenoid has failed.

Another thing that I am thinking but have nothing to back it up is you say the voltage "goes way low." Could it be the starter is failing? The only time the meter will drop like that is under extreme load or a weak battery. Any reason to think the battery or starter are on their last legs?

 

[Kinan]

Isn't there a switch on the clutch pedal that won't start the car unless pushed in?
Maybe it needs adjusting or dirty contacts...
Just a thought..

 

[nsx4fun]

PonyBoy, you've confused me. You said you cleaned the terminals, but then said you were going to check the connections from the battery tonight. What terminals were you cleaning? What do you mean now, saying you will check the connections from the battery? Your first task should have been to remove the battery cables from the battery. Then with a battery post & clamp cleaning tool ($2 item at any automotive store), you remove the oxidized lead from both posts and clamps by spinning the tool in circles. Its like a little wire wheel that goes over posts and into the clamps. Then when you put the cables back on and tighten them down, you have insured that any excess reisitance in this contact has been eliminated. This is the one point on your car where you have the maximum current flow, and any resistance here will cause large voltage drops under the high current demand of a starter motor. If this doesn't solve your problem and you still large voltage drops at the battery when cranking (or attempting to crank), then more than likely, the internal resistance in the battery has become high and you need a new battery. If the voltage stays fairly high (it will drop from 12 down to 9 or 10 on a good battery while cranking), but the engine doesn't want to crank, then either the contact resistance in your solenoid is high or your starter motor is failing.

Fritz

All of the above does assume you have put a good charge on the battery through either driving with a good alternator, or connecting a battery charger to the car overnight.