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Discussion Starter · #1 ·
Hi everybody,
I bought a 280z 2+2 ‘77 last year and love the car! However it has some issues cold starting. I have to run the starter for 4-5 times before it starts. Pretty uncool when you are showing your pride and joy to interested people :)
I was told the throttle body was not original, but cannot find out which parts have been changed.

Anybody capable of identifying which components have been used? It says Hitashi on top of the thing to the right - I don’t know the english word for it…

And any ideas for solving the cold start issues?

Please see pictures.
I am sorry if my question seems stupid - I am used to fiddle with carbureted motorcycles…

Thank you for any help and hallo from Denmark :)

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The cols start valve is located right on top of the standard 280z throttle body in the middle of the housing. It's held in by 2 bolts, has a fuel line attached to it and a 2 prong electrical connector. It is essentially an extra fuel injector that adds extra fuel to the intake system of the fuel to help it run while cold, so it get's to operating temperature quicker. It is controlled by the Thermo Time switch in the Thermostat housing and relies on the Water temp sensor and switch in the thermostat housing to be operating properly and accurately as well.

I've attached a picture for reference.
 

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Discussion Starter · #6 ·
View attachment 111103

The cols start valve is located right on top of the standard 280z throttle body in the middle of the housing. It's held in by 2 bolts, has a fuel line attached to it and a 2 prong electrical connector. It is essentially an extra fuel injector that adds extra fuel to the intake system of the fuel to help it run while cold, so it get's to operating temperature quicker. It is controlled by the Thermo Time switch in the Thermostat housing and relies on the Water temp sensor and switch in the thermostat housing to be operating properly and accurately as well.

I've attached a picture for reference.
Hi Andrew,
Sorry for the late reply. It seems like the cold start valve is there - working or not I am not sure if…
I found this two prong connector tugged away under the ignition (see picture) any idea of what is should be used for?
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Discussion Starter · #7 ·
may want to test the ign switch

Hi Dave,
Sorry for the late reply.
Definitely worth trying.
I think my problem lies with the non-original throttle body… it was installed by the former owner in order to achieve some extra power. Sadly I do not know which unit was installed and how it is connected…
 

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Hi Dave,
Sorry for the late reply.
Definitely worth trying.
I think my problem lies with the non-original throttle body… it was installed by the former owner in order to achieve some extra power. Sadly I do not know which unit was installed and how it is connected…
I disagree. If the throttle body wasn't right for the car it would not only have a tough time starting, but would also run poorly once it's on. The way I found out my ignition switch was bad (I had the exact same issue) was when turning the key, the 'floor temp' light is supposed to come on (if you have one on your central console - which is a CA car thing). Mine wasn't coming on, then the second it flashed on, the car started. The delay is what told me it was the ignition switch.

Lemme ask you this, in your 4-5 key turns - if you turn the key and just let it crank forever will it not start but the second you turn the key again it will? I'm with dave that its probably your ignition switch if thats the case.
 

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Discussion Starter · #9 ·
I disagree. If the throttle body wasn't right for the car it would not only have a tough time starting, but would also run poorly once it's on. The way I found out my ignition switch was bad (I had the exact same issue) was when turning the key, the 'floor temp' light is supposed to come on (if you have one on your central console - which is a CA car thing). Mine wasn't coming on, then the second it flashed on, the car started. The delay is what told me it was the ignition switch.

Lemme ask you this, in your 4-5 key turns - if you turn the key and just let it crank forever will it not start but the second you turn the key again it will? I'm with dave that its probably your ignition switch if thats the case.
Hi chaseincats and Dave,
It is a very interesting theory! And definitely seems like it might be the case. The key looks original with a “Z” logo on it and very worn.
I do not have the floor temp. Light. Is there an alternative way of checking this without removing the key housing (or whatever it is called in English :) )?
 

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Is there a fuel line connected to the cold start valve? I did not see the cold start valve in your included pictures.

The 2 prong connector could be for a number of things. Where does the wiring lead to from that connector?
 

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the only good way is to remove the key switch and test on the bench. Its not that hard IIRC just unplug from the back, think its held in with a couple screws. I highly recommend using a tone or test light rather than a digital meter, it just works better than trying to read a slow responding digital display.
 

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Hello Denmark, I doubt there is a problem with your ignition switch. Don't waste your time there. They ones who are pushing you in that direction must have misunderstood your original post. Also, the cold start valve is NOT located on the throttle body, it's located on top of the intake manifold. Your pic shows the hose that goes to the CSV however there is a black hose or wiring going right over the top of where the CSV is actually located so I can't see if it's on your engine or not. It probably is. Dave M's pic shows him pointing at the CSV, so go by that pic to locate it on your engine. If it's there and there isn't a connector going to the top of it then you know where that loose efi connector should go. The CSV is only going to help a cold start if the ambient air temp is below 65 degrees F, which I think is about 18 degrees Celsius. Above that the system is shut down by the thermotime switch. You're going to need to get a fuel pressure gauge that goes up to at least 65 psi and hook it up right above the fuel filter on the right side. Start the car up and record the regular idling pressure, then shut the engine off and see what the pressure is. It should be between 29 and 35 psi at idle. It usually drops down quite a bit after the engine is shut down. As long as it remains above 8 psi, when the engine isn't running then it's ok. You'll want to leave the gauge on there overnight and check it again in the morning to make sure that you still have residual fuel pressure. If it doesn't hold at least 8 psi then let me know, I sell a one way valve that you can install after the fuel pump that will let you maintain fuel pressure. The original check valve isn't available anymore.
The throttle body won't usually cause a hard starting problem however bigger throttle bodies DO NOT give you more horsepower like the previous owner claimed. The only thing a bigger throttle body will do is empty your wallet faster. My advice is to get rid of that throttle body as soon as you can. If you can get ahold of the previous owner maybe they still have it. If not I have lots of good used ones and I delete the pollution device on the bottom of them called a BCDD which will solve any future grief because all of them will eventually fail.
Hard starting especially cold can also be attributed to the valves being way too loose or way too tight, or a weak spark in the ignition system, or the timing being retarded too much. Good luck on getting your issue solved. Z man of Washington
 
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