Cold start solenoid rewiring bypass

[MikeL43]

I'm looking for the best way to manually wire a switch to the cold start solenoid.  I have had the fuel pump rebuilt (3 times by Hans), the injector pump by a guy in California (recommended but forgot his business name) and the cold start solenoid.  I'm going to recheck the fuel pressure when my mechanic gets back in town but barring a miracle I have given up on trying to fix it.  I suspect the temperature/time thermostat but am not sure that is the problem and the cost of a new one is ridiculous.  I checked the CSS when the car was cold and it only stayed on for a second or two.  I used a hot wire from the battery and the car started and ran though still acted cold.I have seen several posts that indicated that people with a similar problem just wired up a manual switch that worked fine. Soooo, does anyone have some type-of guide that I can use to manually wire a switch to the CSS?     

[A-230]

Hi,

I have a two pole switch under the dash next to the hood opener. A wire from battery via fuse to switch, and another wire from switch to CCS. Opens CCS when I push, closes when i release.

Mine is -64 and all my warm start problems disappeared by use of the switch.

[ja17]

What is the problem your having?

[mistertj]

I've done essentially the same as shown in the photo. My issue was that on occasion with a warm engine, it would not start. Kind of embarrassing so I wired in the intermittent switch/button. Goes from the coil (hot side) to the button and then to the CSS. For hard starting with warm engine...press the button once...she starts!

[Nicolas Aristodemou]

Why don’t you try the modern replacement (solid state) of the Bosch time-thermo  switch also made by Bosch with part number F026T03100 for about €140 from eBay? It would sort all your cold start solenoid valve operation problems, even when car is hot by squirting fuel for about 1 second. I think the cost is very reasonable compared to a replacement original part which is almost impossible to source new.

[wwheeler]

The issue with starting on my '68 280SE was hot, but it was too much fuel. When I disconnected the starting solenoid on the IP, it would start beautifully when hot. But the downside was it needed more fuel when cold. Adding a two pole button in the cabin connected to the cold start valve, gave me the extra fuel when cold. Plus it starts faster because I can pre-load fuel in the manifold with the pump on before I crank the engine. My engine now starts within a second hot or cold.

Adding this switch is a common fix. I basically did what the others are saying. The only job is to figure out when it needs more fuel and when it doesn't. I kept a log with the different variables like engine temp, outside temp and how long after the engine was just started. Life is good with the switch and no more embarrassing no-starts at car shows!    

[MikeL43]

JA asked what was the problem I was having with starting. so here it is: The car won't start when cold and I  Live in Florida so cold is a relative problem.  As I said in my original post, I have had the Fuel pump rebuilt, the IP rebuilt, and the CSS.  I also have new injectors.  Originally when I got the IP back from the rebuild it started fine but after a couple of weeks it went to its current state.  The temperature/timer thingy (forgot the name) is the only thing I haven't replaced and it is very expensive and I'm not sure it is the problem.  I have tried energizing the CSS for about 10 seconds with the fuel pump running and it starts fine.  I checked the time that the CSS stayed on during a regular start cycle and it was only energized for about 1 or 2 seconds as it was being cranked.  I have perused a bunch of previous comments on the forum about the CSS but nothing I saw there helped.  The car starts fine when warm.       

[teahead]

Pull apart the relay and clean the contacts w/some electrical cleaner.

That's what fixed my issue.

[wwheeler]

By CSS, I assume you are talking about the Cold Start Valve (CSV) on the intake manifold? You say cold start solenoid, but that solenoid on the IP richens the IP during starting. It is activated everytime you start (depending on your model which you didn't state). You also mention the thermo-time switch which controls the CSV not the CSS. So there lies my confusion. I was thinking you were talking about manually energizing the CSV which is a common procedure. I have never heard of manually energizing the CSS and not sure it would do anything. It is helpful to know what year and model you have as these cold starting systems vary greatly.   

By having to manually energize for 10 seconds the CSV, sounds like a long time to me. Is this prior to starting or during starting? When I manually activate the CSV prior to starting, the CSV also fires during starting as normal assuming the engine temperature is under 90*F or so. I have it wired so that the CSV can function normally or can be manually energized. However, I never energize mine for more than 3 seconds or so.

It sounds like you may need to diagnose if the Thermo-time switch is working properly which controls the CSV. You can also check the relay that is between the TTS and the CSV as suggested earlier. The TTS switch stays on relative to what the engine temperature is. Colder longer, warmer less. So if the ambient temp is 80F*, it may only stay on a second or two. I believe the cut off temperature is something like 90 to 95*F. So the closer you get to the cut off temp, the less the time it stays on during cranking. There is a section in the tech manual regarding testing the TTS.

Let us know if we are talking about the CSV or the CCS.