Need Help with Unusual Starting Problem

[canguro]

For the past year, I've been trying to diagnose an intermittent starting problem with my '67 Duetto, and tried various remedies (including those mentioned on this Board), with no success.

Here are the symptoms: Car always starts up right out of the garage, where it is hooked-up during the week to a trickle charger. I take it out for an hour run each weekend, usually without lights, fans, or any accessories. Upon parking the car, she sometimes refuses to restart. This seemed to happen more frequently after running the lights during my drive, but it also happens without my using the lights, fans or any other power-draining item.

When I turn the key, I can hear the fuel pump functioning, but the starter won't turn, and there's no clicking sound. Yesterday, I attempted to jump start using a fully-charged portable jump starter (250 amps cold crank/500 amps max), which I had just acquired because of this recurring problem. Still no go. I then jump started off of another running vehicle, and the starter operated without hesitation. I didn't have a multimeter handy to measure the battery charge level, so I don't know for sure if the car battery was flat.

During the past six months, I've replaced the battery, replaced the starter solenoid, and had the starter motor rebuilt. My mechanic had checked the generator only last month, and found it producing a sufficient charge.

I'm leaning towards swapping in an alternator, but even if the generator was the culprit, I'm puzzled that the battery should lose so much charge from an hour-long drive, especially when neither the lights nor fan (no radio) are being used. I also don't understand why the portable jump starter with at least 250 amps wouldn't turn over the starter.

Is this a fault with the infamous generator not providing enough juice to recharge the battery, or something else, such as a faulty ignition switch? Any thoughts or advice would be greatly appreciated.

Iori

[BigSwede]

Next time it happens, try bypassing the ignition switch by runninig a cable directly from the battery to the starter solenoid.
Also get a multimeter and check for current drops over different points, battery to solenoid via ignition and battery main feed to the starter and also be sure to check the ground between the engine and body.

I'd go for the ignintion switch first.

[BeigeAlfa]

Sounds almost like a classic tired battery retaining surface charge, but you've replaced the battery, so that's very doubtful.

Suggestions for further diagnosis:
Next time you take it out, leave the headlights on without the engine running for a couple of minutes, then try and start it. If the battery is surface charged only, you should replicate your non-starting symptoms.

More likely you've got a big current drain somewhere, and you're hiding this with the trickle charger (my car sits all week and starts no problem at weekends). Hook up an ammeter between the battery and the car when it's not running, see what kind of drain you have. Don't try and start the car like that, though, you may break your meter and/or start a small fire.

If you're loosing a lot of current, start pulling out fuses and disconnecting things until it goes away. Stereos, alarms etc may be the most likely suspects, but any old bit of duff italian electrics may be to blame.

I'd be really suprised if a standard car was pulling any current at all when it wasn't running, but if you've got a stereo or alarm it shouldn't really be pulling any more than 10 or 20 mA.

Other than that, I've no idea!

Dan.

[Mr. C.]

Hi,
I have a hunch that you have a bad engine ground. The starter solenoid will not pull in with less than about 9 volts ACROSS IT.
If the starter motor to ground circuit has resistance in it you can easliy loose 5 to 6 volts. The starter mootr and the ground resistance become a voltage divider and the starter motor has to share your 13 or 14 volts from a new battery.
Carry a set of jumper cables and next time the starter fails to work, hook one of the ground cables from the negatve battery terminal to a good solid ground on the ENGINE. Try the starter like that. If it goes, your normal ground is bad.
This problem often shows or goes away depending on where the car is parked because the engine can tilt and self fix the bad ground. I have seen the problem go away if you pull on the engine. If you have an ohm meter, measure resistance fro engine to ground terminal. It must be zero. shake the engine and resistance must not change. Always measure from the terminal itself not the car body or even the cable.

[Keven]

To check the battery:

Check the voltage before you start in the garage, should be about 12V
Now start the car and check the voltage, should be about 13V

Now do your usual run and shut down. Check the battery voltage if she wont start.

Now check all the connections from the battery to the starter. Disconnect the battery, and remove each conection, and clean with electronics cleaner, wire brush off all corrosion, and reinstal and seal with electronic sealer. Do the same cleaning/sealing to all connections to generator, and ignition switch.

If this does not cure your problem try this:

Might want to make sure you add a relay from the ignition switch to the solenoid.

I think the ignition switch gets corroded over time, and does not provide enough amperage(current) to the solenoid to engage the starter. I had the same problem with my 78 spider, and this solved my problem. Also you might want to lube the solenoid to make sure it moves smothely/freely.

Here is a really nice write up from the Kansas City chapter of AROC:

http://www.geocities.com/MotorCity/...7/spicrela.html

For some reason people on this board dont like to add a relay to their starting system, all modern cars have these relays to solve the voltage/current droop thru the ignition switch, so I dont know why nobody here want to do it.
It sure is a lot cheaper than rebuilding starters/alternators/ignition switches, etc.

[BigSwede]

Well I have relays for just about everything that goes thru the ignintion switch...
I almost had a heartattack when I realized that the lights in the 75 didn't have realys in the circuits, ALL the amps went thru the stalk.. The improvement was amazing.
Did the same thing to the Alfetta and it was such a big difference I had to check the bulbs, thought they were a higher watt rating then legal.
Highly recommended.

[Sniady]

First!!! Check battery voltage.

Second, Check voltage at the starter. It should be 12 + volts.

The most common issue. A sticky cold start solenoid (if you have a spica)!!! Unplug it from the spica pump (make sure the connection does not hit any ground!)

Check connections at the starter

[canguro]

Thanks to all for their kind advice! I'll try out each remedy this weekend. Best.

Iori