Hey guys, hope you all had a great holiday. I know I've read a couple posts on this but not sure if anyone had a fix. We have 3 cforce 600 and 1 500Z in our family, one 2019 600 two 2020 600 and the zforce is a 17. The 500 fires right up no matter how long it sits or whatever the temperature is. All of the 600's will crank all day long and will not start unless the key is cycled 3 or 4 times as soon as the temperature drops or if they sit for a week or so. Once they start they're fine. I don't understand, key on fuel pump runs then shuts off, that means there should be fuel pressure, why won't it start unless cycled? Not really a big deal but the wife just don't get it, I can see me buying a starter soon if she keeps it up, thanks in advance for any ideas or fixes

Hmmm ... it sounds like everything is in good working order. Doesn't sound like low voltage. Cranking it a few times might load it up with fuel to make starting easier.

If they were my machines, I would check cold compression and valve lash to make sure the mechanicals are correct. Many cold start complaints have been remedied by lash adjustments. (Has it ever ben done?) After that, I would hook them up to a PDA and look at the sensor data.

Yes, valves were adjusted on all, they were all off, seem to run better and quieter. Did that over the summer. Now my next question is, what kind of scanner can I use? We have a new million dollar snap-on at work but I thought I read it could ruin the tool if plugged in to OBD?

PDAs are not available to the consumer, but you can use the following to make your own.

https://netcult.ch/elmue/HUD%20ECU%20Hacker/

I have a 2019 c600 touring that i bought new and it has done the same thing since day 1.If it sits for a week or so it won`t start unless i cycle the key a couple of times to prime the fuel system. i never really worried to much about it.

[2015 Z Force 800 53/Trail EPS]

Logically, if it has fuel, air, compression and detonation at the right time, it should at least try to start..no matter the temperature..well -40+F is tough to fire even some gasolines. But something must be missing. Just have to find out what. If mine ever started doing that I would look for the problem by: First, after it sat long enough to have that problem I would pull the plug wire and plug-in a spare plug, ground the base and roll it over one or two revolutions to see if there was spark. If there was, I would then pull an injector, leave it plugged in and on the fuel supply and roll it again. If it had solid spray right off the bat, I would test the compression and do a leak-down test. If all that was ok I would test the fuel pressure, engine speed sensor, idle Air control valve. IF..there was any lag or no fuel for a revolution...but then it finally started to spray, I'll tell you a story about a member on another forum and his EFI  nightmare. The guy had something similar happening. Hard starting..more so when it got cold and fine after started. His buddy's machine, same as his, never had any problems starting after sitting a while. He went through all the normal tests. Long story short he had a faulty injector that leaked just a little while sitting and would leave an air gap between the injector and several inches up the supply line. When the pump pressured up this air gap sat against the injector valve seat slowly bleeding off..yes, but not fast enough to give him instant fuel while cranking. He replaced the injector and all was well. So..maybe if this is happening, if one was to pull the injector after running and leave it plugged in and set it on a paper towel, one might just see the towel getting wet from it leaking while it has full pressure on it. Just a thought.

Just a side note. Octane slows combustion so higher compression can be used and higher chamber temperatures can happen without the "ping" of per-detination. Most of us run 89-91 in our machines and that's usually what you want in warm weather. But consider..the colder it is, the colder the air is that's being pulled-in, and that means the combustion chamber temps are also lower so..why not make it easier for an engine to detonate the fuel charge by lowering the octane rating to..let's say..87....especially during cold starts. I do this in my car and in the Z in winter and it does help with faster starts. It was a must when we lived in Iowa and those -20+ winter mornings and out plow trucks HAD to start. You guys in "cold-country" should try it.

Thanks guys, some good info there. Looks like I got some work ahead of me, now all I need is some spare time. I'll post if I find something, I think I'm going right to the injector first

I'll be following this one.

I'll be curious to learn if it is the same problem on all three machines.

[2015 Z Force 800 53/Trail EPS]

I'll be following this one.

I'll be curious to learn if it is the same problem on all three machines.

Yeah me too. Wouldn't think all three would have the same issue. But they do all have a cold-start problem..like many other have reported. What else can cause an EFI machine to have a cold starting problem? Let's all jump in here. Let's see, a weak signal from the CPS, sticking injector(s), low voltage..ie below 11.9 to coils or ECU, low or no fuel pressure, frozen water in fuel filter, low compression from..lots of things..mostly tight valves and/or warn rings, IACV and/or TPS problem, bad ignition switch, bad contacts in kill switch..really really old fuel. What else people? I don't know if it's still relevant with today's EFI systems but in the first days of EFI you could not touch the throttle once the key was on before cranking as it would change the TPS input signal and confuse the controller. If you did it wouldn't start and you would have to cycle the key again and keep your foot off the throttle until it started. Probably not an issue today but I still do not touch mine until it starts..and it always starts by the second revolution. 

Just saw your post. I have a 2019 cforce 600 with exact same issue. Had fuel pump replaced but did not solve the problem. Did you ever resolve the cold start issue?

My uf1000 is hard start sometimes
I find if it sits to cycle the pump once an on the second cycles just before it finishes I hit it an it fires up

In the summer I just let the pump almost finish it's prime cycle an hit it works 99% of the time

If I don't I can crank all day with out that cycle an won't start