Electrical: Starter Doesn't Turn Engine
 

I'm new to the forum. I'm having a problem getting the engine to turn over. I had the battery checked and charged, and it came out 100%. The cables have been cleaned at battery. The starter was removed and bench tested, then reinstalled. When ignition is turned to start position, there is an audible click at solenoid, but the starter does not turn the engine over. So I think there is a problem between the battery and the starter. What could it be? Any suggestions would be great!

Thanks for all your help,

Steve

Steve,

Here's a really good method of checking your starting circuit.

Pelican Technical Article: Starter System Troubleshooting

You'll have to tell us what kind of car you are working on as they vary greatly from year to year.

I see you're in Seattle - lots of help here. Let us know how you are doing.

Clean both ends of the trans. to body ground strap.
Had the same problem with mine and this fixed it.

Sorry it is a 85 911 Targa Carrera 3.2. Could you elaborate on the trans to body ground strap, for instance its proper location and how do I remedy it. I took off the starter and cleaned all the connections and put it back together. When the starter was off I got it tested and it was good. Also, where does the positive battery cable go and would cleaning the other side of the connection possibly help? I can't spot it but it looks like it goes behind the gas tank. Thanks for the help guys!

Ok so I figured out where the strap was. I cleaned both ends of the trans to ground strap. I then tried to start it, and the solenoid clicks, but I'm still not experiencing the starter turning the engine over. Any leads in what to check next??
Thanks

If your starter bench checks ok, clearly you are not getting the proper voltage/current to the starter. either your connection is bad, or your battery is not really healthy.

You can use jumper cables to connect directly from the battery to the starter to test this if you like.

You need to be sure that the Ignition Switch (starter-switch contact) is not arcing which will result in a low pull-current to the solenoid and hence no Starter engagement...

I spent a couple of months trying to solve a similar sounding problem earlier in the year: "click" on key turn, intermittent non-starting which deteriorated into "hardly ever starting".

With mine I suspect the problem was the 14 pin main engine loom connector and the yellow "50" solenoid wire which passes through it. I separated the plug and cleaned the pins and plugs with alcohol (I read that they're silver plated, so abrasives not good). You can then slightly splay the pins again before reconnecting. The other classic location for the yellow "50" wire to cause problems is the bulkhead connector coming loose behind the ignition barrel.

I also replaced the earth straps gearbox to body and battery to body, along with some determined cleaning up of their mounting points.

Because I did several of these jobs on the same day I can't say for certain which cured the issue. However not one start problem since - totally reliable again. These simple and cheap jobs finally resolved the problem.

There's lot's to read up on about the yellow solenoid wire - like probably an evening's worth of material. The summary is that this wire and bad earths are probably the most common cause of non-starting problems on 911s. Some have retained the original solenoid wire but adapted the circuit to use it as a relay feed, taking the strain off it and incorporating a starter switch instead. Others have opted to replace the wire from the barrel to the starter with a heavier gauge instead.

Some other stuff to check too: both parts of the barrel, the starter, the battery - all of which cost you a lot more than the steps above!

You need to test the voltage at terminal 50 (yellow wire) of the starter solenoid with the ignition switch in START position. It must be at least 7.5 V. If not, consider replacing switch (only after you confirmed that the circuit to that point is not open / has high resistance -as noted above)

Test the voltage at the starter-field winding (large bolt) with ignition in START position. It must be at minimum 7.5 V –if not, consider replacing the solenoid.
(note: the solenoid will not switch current to the starter until the drive pinion is fully engaged)

WARNING: You must be especially careful that the transmission is not engaged (not in gear!). It is best to make these measurements with the rear wheels off and the car is safely secured and resting on floor jacks -I can’t stress that enough…!

mean_in_green. It seems like this will resolve the problem. Where can I find the 14 pin main engine loom connector and yellow '50' solenoid? Is one under the dash and one in the engine compartment? Do they pry apart? Thanks

Hey Guys,

I appreciate all the help that I have gotten. I located the 14 pin main engine loom connector and cleaned it, but then I also saw a little button under the dash. It looked like a kill switch, so I pushed it, and tried to fire it up and it started. So who knows that was causing it, but it has started every time since (5 or so times). Thanks again for all the help!

Its great that you have got the car running but if it were me, I'd do some checking to find out what this mysterious button under the dash is. If its a 2 position switch then you probably have a kill switch. If not, then why is it still starting even tho you only pushed the button that one time? It might also be wise to check the wiring to make sure you don't have an overload/fire waiting to happen. Look black electrical tape connections or wire thats too thin for the load.

The yellow "50" wire is the trigger for the starter solenoid and runs from the back of the ignition barrel to the starter, via the bulkhead and 14 pin connectors.

I'm no expert - everything I know about it I read in here. Glad it appears to be resolved - fingers crossed you've cracked it.