Testing Cold Start Valve

No such thing as a dumb question. Only one side of the connector should have the 12V. I would use a volt meter to look for 12V. Then the other side should have continuity to ground. If no continuity to ground with a cold engine, then either the wiring to the thermo time switch is bad, or the thermo time switch itself is bad.

I checked multiple parts outlets, and they all said this part was out of stock. So perhaps this is a commonly failed item, and it might be hard to find one at any price. Ricambi might know of some alternative replacement part, I would ask them.

 

Are you sure that the temperature is getting cold enough to have the TTS reset and close? If it doesn't close, the cold start injector will not fire at the next cold restart. I checked the recent Chicago weather, and you may not be there if you store the car in a garage. IME, a 70 deg F low temp, or even a little lower (and having the car at that temperature for many hours) is marginal for the TTS to reset.

One way to test a TTS is to put it in the refrigerator for a while, then measure the resistance between the W terminal and the metal body of the TTS = it should be 0 Ohms (or just a few Ohms maximum).

 

Yes, that's what I experience with my KE-Jet system here in central TX. Cold starts from about Nov~May are much "crisper" and immediate. Whereas, cold starts from about June~Oct are sluggish and labored.
What year/version Mondial do you have, and what TTS are you using? 113980, 118790, 121778, or something else? I see that 45 deg C reference for the 121778 TTS in Service Bulletin 10-13, but it seems high-ish to me (based on the specs of the others although I have no evidence that it is wrong), and I do believe that they all have some hysteresis (i.e., it opens at temp X, but doesn't reclose until cooled down to temp Y -- with Y<X).

 

Yes, 121778 is used on the 1984-1989 K-Jet with Lambda US V8 models. I can maybe believe that it is designed to open at 45 deg C, but that doesn't necessarily mean that that's the temperature it resets and closes. You can make the same W terminal -to- TTS metal body resistance measurement on the unplugged TTS mounted on the car before the next cold start to see if it's closed or not. If it is closed, but you don't get a voltage at the cold start injector connector during the first seconds of the first cold start cranking attempt = that would be a (another) problem.

If you would, I would love to see you do an experiment where you take your unmounted TTS on a day when the outside temp is something like mid-80's:

1. Put it in some warm/boiling water to confirm the W terminal -to- metal body resistance is high (might not be infinite Ohms, but should be much more than your 0.3 Ohms),

2. Place it outside (in the shade) for a few hours and remeasure the W terminal -to- metal body resistance to see if it closes at that temperature. If it doesn't,

3. Take it inside for a few hours and remeasure the W terminal -to- metal body resistance to see if it closes at that temperature.

I.e., try to determine the approximate temperature where it does reset and close.

 

You've got that backwards -- it opens (high resistance) when in the hot water, and closes (low resistance) when it cools off. Have you measured the (unplugged) one installed on your engine at the (known) ambient temp?

Unfortunately, I don't have the wiring diagram for a 1987 US Mondial. You did write: "the fuse is good" -- does that mean that the 7.5A fuse in fuse position #9 is intact?

 

Do not use any chemicals on the plastic layers of your fuseboard. It will ruin them completly !

 

I believe that that's actually the euro 3.2 K-Jet without Lambda injection schematic (not the US K-Jet with Lambda injection schematic). The wiring for the cold start injector may be similar on both, but they might not (I note that the 7.5A fuse for the cold start injector is in the same physical fuse position in both OMs although it's called fuse #10 in the euro OM and fuse #9 in the US OM). The cover and/or title page for the 1987 US version 3.2 Mondial wiring diagram would look something like this cover and/or title page for the 1988 US version 3.2 Mondial where it specifically has "U.S. VERSION" printed on the cover and/or the title page (unfortunately, all I have is this single image of the 1988 US wiring diagram):

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I've got a pdf copy of the 488/87 wiring diagram, and it's definitely only for euro version (K-Jet without Lambda, Fig 2) and CH88 version (KE3-Jet with Lambda, Fig 4) 3.2 Mondial. Ferrari doesn't use the expression "euro version" like we do -- for them, it's just the "standard" version, so on documents for the standard version, they just don't put any label at all (whereas, documents for US version will specifically have "US Version" printed on them somewhere).

 

Since all we have is the euro schematic for a reference -- if the bottommost wire in your w connector is a BN (white-black) wire, first unplug the w connector and inspect it. If seems OK, plug it back in and try measuring the voltage from that terminal to ground when the TTS is closed and you first crank the starter.

 

The w connector at the fuse-relay panel -- it's the single vertical connector on the RH side of the fuse-relay panel. It's shown, and labeled, in the 488/87 Fig 2 schematic that you posted in post #38. You should be able to touch the meter probe to the back end of the metal terminal holding the BN wire even when the w connector is plugged in.

 

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Steve means the vertical white plug on the right side of your fuseboard, the lowest wire.

 

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You can check where the current is coming from. This is the internal wiring diagram from your fuseboard. Its the backside (mirror view) and split in 2 for more clearness.
W10 gets current over fuse marked 10 (the 9e fuse from left front side fuseboard. On your board the lower connector of the fuseholder nr 10 (My drawing shows upper connector fuseholder.) Same connection goes to relais i 87b.
The other fuseholder connector goes over white plug Y number Y9 and get its current from the ignition switch (a white wire).....
So the culprit can be fusebox or....ignition switch.

 

As Guido wrote, the foodchain to the BN zebra wire in the w connector is:

+12V power goes from terminal 50 of the ignition switch during starter motor cranking (if the starter motor cranks, your ignition switch is OK)

to the largish white wire in the horizontal y connector

to the #9 fuse holder (this gets wacky because on the euro version wiring diagram they count the empty first fuse position as #1 so they, and Guido, label this 7.5A fuse #10; whereas, in the OMs, they skip the empty first fuse position and call this 7.5A fuse #9)

thru the 7.5A fuse

from the 7.5A fuse holder to the BN zebra wire.

I'd suggest that you remove the 7.5A fuse #9, and measure the voltage on each of the fuse holder female terminals relative to ground during starter motor cranking -- one of them should be +12V during starter motor cranking (per Guido's layout it would be the lower terminal).

If one is +12V (or really more like 10V) during starter motor cranking, but the BN wire in the w connector isn't (when the 7.5A fuse is in place) = bad sign for the fuse-relay panel itself.

If neither is +12V (or really more like 10V) during starter motor cranking = bad sign for the fuse-relay panel, or the connection of the large white wire in the horizontal y connector is bad (so wouldn't hurt to unplug/inspect/replug that one, too).

If the large white wire in the y connector doesn't go +12V (+10V) during starter motor cranking (but the starter motor works) = bad connection/broken wire in path from ignition switch terminal 50 to the y connector.

Good Hunting! (But at least you've identified a solid reason why the cold start injector doesn't squirt when it should.)