Quote:
Originally Posted by 911pcars
My suggestion is to begin checking the easy and obvious things first.
Check all battery cable and ground connections. They should be tight and clean with no corrosion between the posts and the cable connectors.
Check the battery to make sure it's fully charged. If you have voltmeter, connect to the + and – terminals. Should read ~12.7 volts or better with no load and 9+ volts when the ignition switch is in the crank position.
If the battery stays at the no-load voltage level during cranking, there's no connection to the starter (cranking should normally produce a voltage drop at the battery. While cranking, source voltage to the entire vehicle normally drops to about 9+ volts, including the yellow solenoid wire.
If the yellow starter solenoid wire shows 12 volts while cranking, the ignition switch is okay, but no current is reaching the starter (maybe bad solenoid).
If the yellow starter solenoid wire shows less voltage than the above, but the starter doesn't move, there could be an internal short in the motor. See bench test below.
Does the solenoid produce any sounds? You should hear it click as it becomes energized in the crank position.
At this point, remove the starter assy. from the engine, then bench test it by connecting battery jumper cables to the solenoid. Clamp the ground jumper wire to the starter motor frame.
If it still doesn't work, you can attempt to disassemble and troubleshoot it yourself or trade it in for a rebuilt starter assy.
There's a chance only the solenoid is malfunctioning. Bypass the solenoid by firmly contacting the + jumper cable directly onto the starter motor post. If the motor now spins, replace the solenoid. However, it's probably more convenient to purchase a complete starter motor assy. than to find just a replacement solenoid; maybe not.
Hope this helps,
Sherwood
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The battery is less than 6 months old, and when the starter does work, there's no hesitation or symptoms of a weak battery. When it works, it works perfectly.
I'm thinking the ignition switch itself is a likely culprit, so I might give that a try, and see if I can't diagnose that.
The weird thing to me is that, for instance last night I got it home, and then it wouldn't start in my driveway. I roll-started it and pulled it into the garage, at which point it started flawlessly 3 more times.
Quote:
Originally Posted by 1990C4S
Excellent advice here. I am guessing it's not the battery or the cables, it's possibly your key switch, but I think it's a flakey solenoid.
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Seems like solenoid or switch is a likely candidate.
Quote:
Originally Posted by psalt
Hi Brandon,
Yes, I think we met at one of Mike Eck's Jaguar meets years ago. You will find lots of posts about intermittent starter problems on this list. The starter circuit draws a hugh amount of current compared to any other circuit in the car and the distance from the battery to starter can be an issue on the 911. On a well designed front engined car, there is a short positive cable to the starter and a short negative cable directly to the engine block, but this is not true for the rear engined 911. The starter switch wiring also goes through several connectors that can be bad all the way to the back of the car and if the car has A/C a relay that can cause problems. Many will tell you to start by disconnecting and cleaning the ground cable at the battery, the chassis ground post(s), the ground strap at the gearbox which is good advice. I usually use a single jumper cable from the battery terminal under the car directly to the starter body to see if this is the problem. Many times it is not. My experience is that when ever you have a starter problem, suspect the battery first. Only after you have the problem with a fully charged, known good battery, move on to the other parts. An intermittent problem is tough to diagnose, you really need to be ready to test it when it is failing. This presents another problem with the 911 because you can't get at the starter and jump it with a screw driver like front engined cars. I always advise installing an $8 remote starter button in the engine compartment on 911s, so that if you have an intermittent problem, you can get out and fire it up on the button. Many times the extra juice to the solenoid is enough to get it to spin. I do not recommend attempting to clean or replace the solenoid. You have to unsolder very large lugs and the replacement solenoids are from Mexico or China and do not last long. If you read all the posts on starter problems you will find several people that have had Bosch factory rebuilds fail within a year. This is also my experience, and it is more frequent today then 10 years ago. My advice if you need a replacement is a hi torque starter, you can find them in many places and on E bay. By the way, if your car has CIS and an intermitent starter, be aware that the CSV will be spraying fuel everytime you hold the key down and the TTS wil not close it before the engine is flooded.
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I do not have A/C, I do have CIS.
Do you have pictures/wiring diagram of the proposed engine bay mounted ignition switch?