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Posted by: Double D Mar 31 2020, 01:40 PM

I have a 75 1.8L engine. A month ago the car started and ran just fine. Two weeks later the car would not start. The headlights come on but still doesn't start. I checked the battery, started motor, ground to the chassis, fuses, relay board, ignition coil and ignition switch. I can jump the starter motor with a screwdriver. I'm just not getting juice to the solenoid switch. Any suggestion

Posted by: porschetub Mar 31 2020, 02:11 PM

Looks like you have done a few steps to find your issue,how did you check the ignition switch ? the only way to test it is to get a second person to turn the key to start position and then meter the yellow solenoid wire and see if you have 12volts if not you have a bad switch.
In my case the engine would crank and then later not ,other functions did the same thing ,a short time later I had no starter power and the switch had totally failed.
These faults occurred over a period of a few days,I fitted a new switch and everything was normal again and has been ever since.
If you have replaced the switch recently don't assume that isn't the issue as other folks on here report early failures with some replacements.

Posted by: Coondog Mar 31 2020, 04:04 PM

You have a great Porsche repair shop right down the road from you.
Holleran's Performance in Auburn.

Posted by: Root_Werks Mar 31 2020, 04:11 PM

If you turn the ignition on and jump the starter, does it start and run?

Posted by: Tdskip Mar 31 2020, 06:12 PM

^^^^^^^
Carefully try that and let us know.

Posted by: Frankvw Apr 1 2020, 02:09 AM

on the startmotor there is a small connector, the wire with the smallest diameter. Please check that one.

Posted by: rfinegan Apr 1 2020, 06:15 AM

Check the seat belt relay under the passengers seat, it interrupts the starter circuit

Posted by: Frankvw Apr 9 2020, 02:46 AM

Hi, did your problem get solved by any of the tips/hints that were given ? I see it was your first post on the forum, so let us know !

Posted by: lierofox Apr 9 2020, 12:31 PM

To add a bit more context, certain years of 914 have a circuit that uses an early form of occupancy sensing to check and see if the seatbelt is fastened.

If the seatbelts aren't fastened, there's a relay that will prevent power from the key from going to the starter. The relay that controls this is located under the passenger seat.

Since the area under the seats can see a lot of moisture and other nastiness, and since these cars are now well over 40 years old, those components have a habit of going bad.

The most-guaranteed fix for this problem is to remove the passenger seat, remove the relay, and splice the THICK yellow wire together with the THICK yellow and red striped wire. This will bypass the lockout and allow power to flow straight from the keyswitch to the engine bay.

http://www.914world.com/bbs2/index.php?s=&showtopic=340207&view=findpost&p=2741596

Posted by: ClayPerrine Apr 9 2020, 01:19 PM

If your engine will crank but not fire, then remember "FAST"

F = Fuel. Make sure you are getting fuel into the engine. If it is carbed, look down the bores and open the throttle. You should see the acclerator pumps squirt fuel in to the bores. With D-Jet injection, pull the injectors and put them in small glass jars (shot glasses work great". Disconnect power to the coil and crank the engine. See if the jars fill up with gas.

A= Air. for carbs, this is simple, but it applies to both FI and carbs. Make sure you don't have any air leaks in the system. Check all the hoses and lines on an FI system.

S-= Spark. Make sure you have spark all the way to the plugs. (don't forget to reconnect the power at the coil after testing for fuel). It could be lots of things there.

T= Timing. Follow the manual and make sure the ignition fires at the right time. * degrees before top dead center works great as a starting point. Once you get it running, you can set the timing with a light.

If you want a quick and dirty test, just shoot some carb cleaner into the engine. If it fires and then dies, you have a fuel system issue. If it doesn't, you know the ignition system is not working.


Good luck!