Only starts when jumped..?

[JohnnyP]

I posted a thread on here a few months ago having to do with my 280z not running. After checking the fusible links, battery cables, contacts, grounds, any and all other suggestions that were made, I decided to get my battery load tested (per suggestion) and sure enough it had really poor amperage. So i get the new battery and still the car just wont start on its own. When I jump it, it runs fine and I can start it maybe once after that, without a jump, and than nothing. Could this have something to do with the starter, or starter solenoid? Im not as experienced with cars as others, so Im trying to glean all the information I can, any help is really appreciated.

Thank you,

John

[SteveJ]

Well, you may want to inspect your negative battery cable at both ends. Do a continuity check from the post of the battery to a bolt on the engine. You should only see a tiny amount of resistance. If there is not a good connection from the battery negative to ground, it would result in a voltage drop that could keep the car from starting.

[FastWoman]

Are you sure your starter is in good shape? You can have that tested too.

If you can measure ANY appreciable resistance in the battery cables, they're no good. The better way to test them would be to measure the following voltages with the starter engaged:

Battery + post to starter +

Starter + to Starter -

Starter - to battery -

There should be very little voltage on the first and third measurements. Most of the voltage drop should be across the starter. If there's a large voltage across either of your cables, it's probably bad.

Cables are pretty cheap anyway. I'd probably just replace them for good measure. Cables don't suddenly fail. Rather, they fade away over time.

Edited January 8, 2010 by FastWoman

[JohnnyP]

Another interesting tid-bit, when I tested the battery (just for kicks) its giving me a low signal. This leads me to believe that something is draining the battery. I tried using the body of the car as a ground to see if a bad wire somewhere might be transferring a charge onto the body of the car itself. No such luck. Any possible suggestions on where/how to narrow this problem down? In the meantime I will take the above advice and put it to work.

Thanks a lot everyone,

John

[Curtis240Z]

Did you clean the posts on the new battery and the inside of the battery cable leads? Change your battery cables as FastWoman suggested. If that doesn't do it then change the starter.

If your battery is being drained check the alternator first.

Edited January 10, 2010 by Curtis240Z

[dimitri_zee]

Check the condition of your alternator / regulator. If neither are working, while the car starts and runs, it is running off the battery hence it only starts once or twice then runs out of power. Place a multimeter across the battery and check the voltage while the engine is running. There should be around 13.8-14.5 volts. If its below that check the charging system.

[stevef1972z]

When I picked up my car, the cables had been replace, but the prior owner used bolt on battery post connections. The cables were coroding from the inside out, unseen under the insulation, this caused a great deal of resistance and caused starting issues for me. My car is not restored to show room or even close, so I installed new sealed cables from a local parts store and solved the problem.

It is well worth the time to test the resistance of the cables.

[DeesZ]

Many electrical gremlins were eliminated for me when I replaced my old battery cables. If they have any age on them, it is something that you will need to do anyway. $20.00 well invested. NAPA has what you need, just take good measurements before you go. They even have them made with additional leads for your ground and or hooking up accessories. As Stevef1972Z said, they will deteriorate "from the inside out, unseen...."

It's easy to throw lots of money at problems like these only to find out that it's something that was discounted early on.... (ask me how I know).

[JohnnyP]

Checked the alternator (while the car was running) and it is in good shape. Im getting a solid signal across the battery cables, although I do plan on replacing them soon. I believe the problem is in the starter. I will do some more searching on the problem just to be safe. If a bad starter is the case, what are my options for fixing this problem?

Thanks once again,

John

[spitz17]

Had the exact same problem on my 240Z. I am not sure how many watts your 280Z alternator is, but my solution was purchasing a adapter from MSA, and a 280ZX 70 Watt Alternator (has a internal voltage regulator). It was still a little iffy, so I changed my non-leaking battery. Turns out it was just the battery, but it's good to have some new electric equipment on my car, in any case.

[SteveJ]

Checked the alternator (while the car was running) and it is in good shape. Im getting a solid signal across the battery cables, although I do plan on replacing them soon. I believe the problem is in the starter. I will do some more searching on the problem just to be safe. If a bad starter is the case, what are my options for fixing this problem?

Thanks once again,

John

Okay, I'll bite. What's a solid signal? Did you just check continuity across the battery cables?

Why do you think it's the starter? What's the voltage at the solenoid when you try to start the car?

Option 1: Diagnose the problem. (See you FSM or Haines manual for diagnostic procedures.)

Measure the resistance of the battery cables in ohms.

Measure the voltage at the solenoid when you try to start the car both with your battery and when you jump-start the car.

If you aren't getting enough voltage to the solenoid, it won't engage properly. You can replace the solenoid without replacing the starter.

However, if it's just the battery cables, you pay about 1/3 as much for the solution.

Option 2: Throw money at the problem.

Buy a starter. Buy battery cables. If that works, fine. If not, buy more parts.

I apologize if I sound harsh, but I tend to be direct. Take measurements and post facts. You'll get a lot less guessing and much better answers.

P.S.: Don't forget to check your fusible links. They are getting old.

[JohnnyP]

SteveJ, your absolutely right. My last post was fairly uneducated and unnecessary. Here is what I did this morning:

Jumped the car and let it run for about 10-12 min to charge the battery. After, I turned it off and had it sit for about an hour - hour and a half (all this time leaving the battery connected).

When the car was both on/off I took these measurements: Battery + post to starter +, Starter + to Starter -, Starter - to battery -. When testing the starter to itself (car off), and to the battery (car off) I received no signal, and when testing only the battery (car off), again, nothing.

So in about an hour and a half, my battery was drained. I retract my previous post, because I am almost sure the problem is in the cables, but I could be mistaken. The last thing I did was jump the car again, let it run for 10 minutes in hopes of recharging the batter (and when I go out to restart the Z, I will be able to see if I simply have a bad battery) and than parked it and completely disconnected the battery, which is now in my basement (no, not sitting on the cement )