re-wiring former race car, starter not cranking |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
re-wiring former race car, starter not cranking |
RFoulds |
Apr 30 2023, 06:52 PM
Post
#1
|
Green Teen 66 Group: Members Posts: 837 Joined: 10-August 09 From: La Quinta, CA Member No.: 10,656 Region Association: Southwest Region |
Car has been off the road for a while. jst got motor back from Jorge at European Motorworks in Hawthorne. freshly rebuilt. while motor was out, I rewired dash to eliminate some of the race car stuff like push button start with no keys. SO i have reinstalled stock steering column and ignition switch.
with motor back in, I have 12 volts to the starter verified by multimeter. but when I turn key, nothing happens. multimeter shows just 3 volts to the solenoid terminal connection from the yellow wire, and only momentarily when key is turned, not constant even if key is held there. in rewiring the ignition, I may have missed something but, whoever installed the start button just hacked off the wires so it was pretty easy to just reconnect color to like color. One possibility is seat belt interrupt. I know 74 had that, but this is an early 73. I believe it only has seat belt warning light. but, with the light not being installed, and the set belt switches not in place, would that interrupt the starter circuit? I can only follow wiring diagrams so far, flow diagrams are a mystery to me. there is a yellow wire and two grounds at the rear of tunnel that were probably the seat belt warning light system. Does anyone know, if these interrupt starter circuit? |
bkrantz |
Apr 30 2023, 06:59 PM
Post
#2
|
914 Guru Group: Members Posts: 7,766 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains |
Transaxle ground strap in place?
|
RFoulds |
Apr 30 2023, 07:01 PM
Post
#3
|
Green Teen 66 Group: Members Posts: 837 Joined: 10-August 09 From: La Quinta, CA Member No.: 10,656 Region Association: Southwest Region |
|
Superhawk996 |
Apr 30 2023, 07:18 PM
Post
#4
|
914 Guru Group: Members Posts: 5,824 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
Sounds like you have a big voltage drop occurring somewhere in wiring to only have 3v at solenoid.
Schematic is your friend but here is the general route of the yellow wire Ignition switch to seat belt relay interlock (maybe gone on a race car) to relay board in on pin 1 from cabin - out on pin 6) to starter. You’re just going to have to ohm it out and trace the wire - god only knows what was done with race car wiring |
davep |
Apr 30 2023, 07:20 PM
Post
#5
|
914 Historian Group: Benefactors Posts: 5,143 Joined: 13-October 03 From: Burford, ON, N0E 1A0 Member No.: 1,244 Region Association: Canada |
I would suspect the ignition switch, but the relay panel in the engine compartment and the harness connections to it could also be faulty.
|
76-914 |
Apr 30 2023, 07:48 PM
Post
#6
|
Repeat Offender & Resident Subaru Antagonist Group: Members Posts: 13,502 Joined: 23-January 09 From: Temecula, CA Member No.: 9,964 Region Association: Southern California |
Verify 12v on that large yellow wire either in the cabin or before it goes to the relay board. I agree with the switch theory. BTW, your batteries in your VOM are good, aren't they? (IMG:style_emoticons/default/beerchug.gif)
|
RFoulds |
Apr 30 2023, 07:50 PM
Post
#7
|
Green Teen 66 Group: Members Posts: 837 Joined: 10-August 09 From: La Quinta, CA Member No.: 10,656 Region Association: Southwest Region |
Sounds like you have a big voltage drop occurring somewhere in wiring to only have 3v at solenoid. Schematic is your friend but here is the general route of the yellow wire Ignition switch to seat belt relay interlock (maybe gone on a race car) to relay board in on pin 1 from cabin - out on pin 6) to starter. You’re just going to have to ohm it out and trace the wire - god only knows what was done with race car wiring thats some good info, thanks! |
r_towle |
May 1 2023, 04:15 PM
Post
#8
|
Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
yellow wire from ignition switch.
Go up under dash, at the front of the tunnel. Find the wire. Use a sewing need for this. Jam the needle into the center of the wire. Does the wire have 12vdc at start position when you test the sewing needle to ground with a volt meter? If yes... Go to rear of tunnel, see if the yellow wire comes out of the tunnel and goes under the passenger seat into the logic circuit (looks like a relay, but its not) Same test, with needle. If it goes into and out of that box that looks like a relay....remove both ends and redo them to make them directly connected and no longer go through that box. There are many pics here...but its two solid crimp connectors, hard wiring that yellow wire. Check the voltage at the starter again in the start position. |
RFoulds |
May 8 2023, 05:52 PM
Post
#9
|
Green Teen 66 Group: Members Posts: 837 Joined: 10-August 09 From: La Quinta, CA Member No.: 10,656 Region Association: Southwest Region |
FYI, I was able to track this down. Yellow wire IN TO the relay board, had a bad connection. starter is working now. but, on first fire up, the new motor made a horrendous noise. Turns out my almost new Bursch SS twin pipes had a loose baffle/. now waiting for that to be repaired.
|
bkrantz |
May 8 2023, 06:35 PM
Post
#10
|
914 Guru Group: Members Posts: 7,766 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains |
FYI, I was able to track this down. Yellow wire IN TO the relay board, had a bad connection. starter is working now. but, on first fire up, the new motor made a horrendous noise. Turns out my almost new Bursch SS twin pipes had a loose baffle/. now waiting for that to be repaired. Keep after it. Only 98 surprises to go. |
Lo-Fi Version | Time is now: 17th May 2024 - 03:51 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |