Hi all-

I posted a week or two ago about a cold start problem with my 1980GT. The only suggestion was that I had a problem with the warmup regulator. Yesterday, I decided to take a minute and see if the cold start injector was working, since it's right on top and easy to access. Lo and behold, crank but no fuel from it. Checked with a voltmeter on the wiring, no voltage. Jumped the injector straight to the battery, and a really nice jet of fuel comes out.

So I start thinking it must be the thermal time switch... but then, it occurs to me, that this car isn't started with the ignition switch, there's a pushbutton on the dash rigged up by the PO. Obviously, that's the first piece of the problem, no signal to the TTswitch from the ignition.

My question is, on a theoretical level, should I just hook the pushbutton start button to the TTswitch? Maybe just hook the start button straight to the cold start injector? Or should I take the time to figure out why the key doesn't start the car anymore? How big a deal is it to troubleshoot the ignition switch?

The car is pretty nice, all original, rust free, so I don't really want to make a mess of it. OTOH, there are a fair number of odd looking wiring fixes and jumper wires running around the engine bay already.

Many thanks for any advice... this board is awesome.
Kyle
--
1980 242GT 197K, 1990 744Ti 113K

The thermo-time switch is supposed to get power from terminal 50 on the starter solenoid via a blue-yellow wire. The starter gets power via another blue-yellow wire from ter. 50, through the big connector on the firewall to the ignition key. The two wires on the CS injector go to the thermo-time switch.

If I read that right, Key->firewall plug->starter->TTS->CSinj, then the TTS should get power when cranking regardless of the source of the 12v+in, so long as the blue-yellow wire is still connected to the solenoid.

sounds like the TTS is bad, then. I'll pull it out and test it. Closed when cold, open when hot, yes?

Does it protrude into the cooling system, or just get its temp from the cylinder head?

Many thanks! I'm confident I can fix this thing now. Lemmetellya, 30+ seconds of cranking to get it started is a DRAG.

Kyle
--
1980 242GT 197K, 1990 744Ti 113K

Kyle, I just checked the diagram, and feel there may be some misunderstanding of the CSI and TTS operation. Forgive ne if this is redundant, but here goes:

Of the 2 wires going from the CSI to the TTS, only ONE has POWER on it -- the BK/Y one. The White wire is the GROUND for the CSI -- via the normally closed TTS contacts.

The BL/Y POWER goes to the TTS for it's Heater, which opens the CSI grounding contact after about 12 seconds of cranking. Reason? If it hasn't started in 12 seconds, it likely to be flooded, so stop squirting extra fuel.

As you know, the BL/Y Power goes to the starter (for starting), at the same time, it goes to the CSI (for squirting, if the TTS gives it a ground), and at the same time, it also goes to the TTS Heater to limit the CS operating time.

Hope this helps,
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and still here)
New 144 from '67 to '78
Used '62 122 from '63 to '67

Thanks, Bruce! That actually makes a ton of sense... when I cut the wiring pigtail for the CSI off the harness, there was one white going to one terminal, and two blue/yel going to the other. One is inbound power from the starter solenoid, the other is outbound power to the TTS heater. Man, that explains a lot about how that works.

'Course, it's all for naught now that I've got it hardwired to the starter button:-) But it starts right up in the morning, and that's what counts.

Kyle
--
1980 242GT 197K, 1990 744Ti 113K

Yes on the path. Not sure about the coolant, but I believe there's a copper washer (reusable) under it so I'd say it's wet. You could check for 12V on both TTS terminals. Cold is defined as below 86F (30C).

I should have mentioned that! On a lot of cars the connector to the TTS falls or is broken off. Yes, that is also a classic. The TTS grounds the cold start and you could control it (the cs injector) with a ground but I always just rehooked the TTS.

Sounds like your car has the common wire rot problem. Rebuilding or replacement
of the engine harness might get you back to key starting.

Re: wire rot - I suspect the same. At the large grey connector block (yay, let's put this delicate electrical thing RIGHT NEXT TO the engine!) the wire insulation is cracking and falling off. It looks like some wires have been replaced in segments with crimp on butt connectors, not my favorite (I'm a soldering kinda guy).

However, 245LVan's post last week about wire rot on his '77(?) netted several replies that said the failure prone wiring wasn't introduced until '81.

Where can I get more background on the wire rot, where the trouble spots are, what to fix and what to leave alone?

Many thanks. I like the pushbutton, but really wouldn't mind using the key:-)

Kyle
--
1980 242GT 197K, 1990 744Ti 113K

My '80 260 had one of those push to start buttons when I got it. The
wiring had crumbled just like yours. I put in a few patches + tape
and got back to key starting. This is a very common problem. Someone
on the board used to offer a diy repair kit with wires to patch in.