I've installed new electric fuel pump to replace original mechanical one due to newly installed webers. I was already wiring the pump when I realized the car (early 260) has original wirings and 2 relays in place. would be nice to use original wires and relays of course but is there any disadvantage in using 40 years old stuff? for example the wires might be a little small and there might be a potential risk of over heating?

on the other hand, before firing up the engine for the first time since head with new cam was installed, I wanted to see if there is oil pressure so I took off plugs and disconnected coil. Started but nothing went on in the dash when I turned the key to "on" or "start". the starter turned great, radio works, lights go on but dash remains "dead". no warning lights, gauges like amp or oil pressure show no activity. They worked before, and I've checked all fuses and all wires seem to be connected. The only difference in the system is that now the new electric pump is connected to the original wires from the relays. I'll disconnect that and try again - but it would seem unlikely that this connection would have a symptom like that?

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http://kingofapes.blogspot.com/

In the early 240s (1970/71) and most old American cars, turning the key to the START position uses a separate circuit than the ON or RUN position. START diverts all electrical power to the simple ignition circuit until the engine catches. During that time, I don't get any readings, either. As soon as the engine starts and I release the key to ON, the gauges come to life.

That makes sense. The engine might be trying to start under difficult conditions, so it might need all the 'juice' we can send it. There's no sense trying to run the radio, windscreen wipers, and gauges during the brief seconds the engine is struggling to start.

I would worry about it if the dashboard remained dead after the engine started.

Before the engine starts, the only reactions you should see by turning the key to ON would be the fuel gauge slowly rising and the ammeter slightly 'ticking'. You could turn the key to ON and try turning on the headlamps, to zee if the ammeter is registering current flow or not.

Frank

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1970 240Z

Frank, when the key is in the ON position there's no warning lights, fuel gauge does nothing either. normally when you turn the key to ON you should have at least red oil pressure light on, right? i have nothing.

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oh well I've been talking (partly )nonsense. I don't know where I got the idea that my 260 has an oil warning light from.. as it obviously doesn't. anyway, there was a problem with fuel, amp, water temp and oil pressure gauges. they did not show a sign of life when key was ON. also, first I had high beam light on the dash, the I didn't. Hazard switch light would not go on, even though hazard light itself worked. Then the switch light would go on even when lights were off and key was OFF. Then suddenly fuel gauge needle would go up. Then it wouldn't. Then it would again.

got a friend who is a car electrics guru and lives about 600miles north to see wiring diagram for me. He emailed me back an hour later and asked me to check connector number c3 (if I remember correctly). I did that and found that it was very oxidized. cleaned it and voila: fuel gauge works and even oil pressure gauge goes up from the bottom to 0 when the key is ON. BUT it doesn't go up when starting. I suspect this is just because it's what it is. It's always been reading pretty much 0 anyway when idling, and will go up only when rpm goes up. But I never had a problem with oil pressure. it's just the way this old gauge works. So I do think there is oil pressure. Cam is oily after turning the starter. (I haven't attempted real start yet as I need to wire fuel pump again. I tried using the original wires but get no power at the pump. I don't know if the circuit had emission devices in it and as they have been removed, maybe some of the wiring for the fuel pump isn't there anymore. So I need to use new wire instead.)

tomorrow I'm not able to work on it but Thursday I think I'll be able to wire the pump and give it a go. the first start-up since winter and since the head was taken off for new cam and porting. I'm very excited already although I'm sure there will be a lot of work until she runs well (triple webere, timing..)

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http://kingofapes.blogspot.com/

Yeah, I stopped breathing when you wrote about an oil pressure light I wondered if we were talking about the same car, or if I needed more sleep?

I have a wiring diagram for the early 240Z carz but I know the 260 is WAYYY different than mine. Your Electron Guru sounds like a guy to know! Wish he live here!

You know King, what you SHOULD get when you turn the key to ON is the handbrake light. Maybe that's what you were thinking of when you said oil light.

Also, your 260 probably has little 'dingers' in it to warn you about open doors, unhooked seat belts, etc, and those might work with the key ON.

Sounds like you have solved the problem. That 4-way flasher switch is the collection point for nearly ALL the electrical systems in the early Zs. Seems like somebody stayed up late one night and designed the whole electrical system in a few hours. On my electrical diagram, the 4-way flasher looks like an aerial photo of the switching terminal for about 4,000 railroad tracks. Everything comes/goes there. Not surpriZed the problem was located in it.

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1970 240Z

Frank, that's right I was thinking of the handbrake light.. in my Alfa there's a small red oil pressure light every time I turn the key to ON, and as I am always really careful about an engine getting oil the light is the first thing I notice if it's not there. Well it was last year october since I drove the Z last time so i didn't have in active memory what happens when the key is turned to ON..

i agree the wiring in the z is an amazing spaghetti railway to h*ll. for some reasosn certain connectors also seem to oxidize easily while others never do. I would like to take all wires out and clean every single connector to be sure they all shine, but obviously I'm not gonna do that..

the door dingers actually go on when the key is in the ignition lock period. even if the key is turned all the way down it still sings if the door is open.

anyway, today and tomorrow I'm not home but when I return I'll connect the pump and will try to fire her up. pray for me.

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http://kingofapes.blogspot.com/

Dude, we pray for you daily.

Owner of one of only TWO Datsun Z carz, wayyyy up there on the Frozen Tundra, far from any partz sources....

You need our prayers!

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1970 240Z

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http://kingofapes.blogspot.com/

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http://kingofapes.blogspot.com/

If you have Weber carbs on your 260, you can simply remove the electric fuel pump altogether and just run a stock mechanical pump. The wiring for the electric pump in the 73 and 74 cars was a cobbed-in mess; the electric pump was a band-aid fix for a vapor lock problem that the original flat-top smog control carbs had. It was installed in addition to the mechanical pump and had an excessively complicated and unreliable system of relays to turn it on and off. You didn't say what kind of Webers you are running but I have run triple Webers on the mechanical pump alone with perfect results, and also the dual downdraft setup Weber makes with the mechanical pump but I had to run a Spectre fuel pressure regulator (costs about 20 bucks) to slightly reduce the pressure; I was getting about 8 lbs with the mechanical pump before that and the downdraft webers like 3-5 lbs.

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

hi in fact I have installed a new electric pump as I was told the mechanic pump won't be sufficient for my engine (I have 3 40dcoe webers, a ported mn47 head with a performance cam and 10,5:1 CR). I was just wondering if I could use original wiring to feed the new pump but I gave that up already as it didn't work. instead I'm using 2 relays wired following a scheme given to me by a car electrician friend. I'm using a holley pressure regulator as well.

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Whoever told you the mechanical pump was insufficient was wrong.
If I were you I would stay with the mechanical but if you go electric there are several things you need to watch out for in order to avoid burning yourself to death. The first is that the pump MUST be wired in such a way that it will not continue running if the motor is stalled but the key is still in the "run" position. If you wire the pump so that it just turns on and off with the key, you are creating a very hazardous situation; no modern cars are set up that way.
Secondly, if you use an electric pump, you must make sure that it is the low-pressure type specifically designed for carbureted cars. A pump made to work with a fuel-injected car produces far too much pressure and will cause your carbs to flood with fuel so much that they can leak out the intakes and make your car explode. Furthermore, all of the fuel lines in your car will have to be replaced (including the return lines) with tubing designed to withstand the higher pressures. If you decide to try to run a high-pressure pump with a regulator, you still must replace the fuel lines because if the regulator fails or a fuel line gets clogged; the car can explode.
There is absolutely no advantage whatsoever in running the electric pump. Many of them are noisy, they are located in a position where they are exposed to road spray and dirt, they don't work if you have a dead battery, they cost more, and are less reliable. They Will not give you one iota of performance improvement. The mechanical pumps are a clean, simple, reliable, and cheap setup that will last for hundreds of thousands of miles without any problems.

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71 on a rotisserie, two more in pieces in my shed...and a 69 1600 waiting for me to get to it

Mark has a point. Pumps push fluid better than they pull fluid, so the rear-mounted electrical fuel pumps were a solid step toward solving the horrid Vapor Lock (fuel starvation) problems of the 1973 cars. Those with the 'flat top' SUs would heat up enough to vaporiZe the liquid fuel in the fuel lines around the engine, and the mechanical pump simply wold not pump vapors. You had to wait until the car cooled down to restart it.

By mounting an electrical pump wayyyy back in the "cold" rear of the car, it could push cold fuel up thru the fuel lines and displace the vapor with actual fuel. The flat top SUs then got actual fuel instead of fumes, and the car restarted.

Today we don't have many problems with Vapor Lock or after-boil or percolation, due to better cooling systems and fuel injection (altho Ross recently complained that his fuel-injected Black Pearl was vapor-locking if he turned it off briefly after a hard road run).

The danger Mark brings up is that an electrical pump might continue to push raw fuel up to the engine under the 'wrong' circumstances ~ such as, when the front of your car is wrapped around a tree (accident) and the fuel lines are broken. Then, unless the pump has been wired to SHUT OFF instantly when fuel pressure drops that far, it might happily go about squirting fuel all over your hot engine while you try to unhook your seatbelt harness.

Frank T

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1970 240Z