Fuel pump

[240260280z]

Just use the mechanical pump.

[conedodger]

Blue, it starves the triples at WOT...

[conedodger]

Still on a quest to wire the fuel pump into the factory harness. Sadly, I do not have the two relays and two harnesses depicted in Carl's attachment above.

If you have a parts car - I need the following:

RELAY A - 25235-P0100

RELAY B - 25230-89915

HARNESS A - 24032-N3300

HARNESS B - 24034-N3300

[conedodger]

FYI, if you still have a voltage regulator in the car, you can wire the (a) fuel pump relay like the factory did. Nissan used two sources for the coil on the fuel pump relay. The first one was from the solenoid for starting the car. The second was from between the alternator and voltage regulator. This way the fuel pump would no longer get power if the engine wasn't turning. If you have an internally regulated alternator, you should look into an oil pressure switch for the fuel pump relay.

SteveJ, Questions about your comment. First, did Nissan use both of these sources at the same time? Isn't the solenoid only powered while the car is starting? Or is it powered all the time while it is running? My car still has the voltage regulator it came with. Well not the one it came with but stock...

[SteveJ]

SteveJ, Questions about your comment. First, did Nissan use both of these sources at the same time?

No

Isn't the solenoid only powered while the car is starting? Or is it powered all the time while it is running?

When starting the car, the same wire from the ignition switch that powers the solenoid energizes the coil for the fuel pump. When the engine catches, the alternator will be turning fast enough for it to generate enough voltage to coil. The actual source from the fuel pump doesn't change. Only the switch that completes the circuit changes.

My car still has the voltage regulator it came with. Well not the one it came with but stock...

There is a chance you already have the fuel pump wiring fully in place for a 73. I'll try to dig around and locate the wires you should be looking for.

[conedodger]

No

When starting the car, the same wire from the ignition switch that powers the solenoid energizes the coil for the fuel pump. When the engine catches, the alternator will be turning fast enough for it to generate enough voltage to coil. The actual source from the fuel pump doesn't change. Only the switch that completes the circuit changes.

There is a chance you already have the fuel pump wiring fully in place for a 73. I'll try to dig around and locate the wires you should be looking for.

I do have the wiring in place. Two bullet connectors taped over in the harness back by the fuel pump. I think that requires the other harnesses and relays found in Carl's post of the Nissan document. Bottom line, the green cable isn't hot.

[Montezuma]

All the US Spec. Datsun 240Z's 70-73 had wires in the harness for an electric pump. They were wrapped in the harness, and not used until later production 73's. Yes, you have to put a jumper in the harness under the dash to supply power to the rear.

When the 73's first arrived they did not have an electric fuel pump installed. It was only after the 73's were found to have significant problems with vapor lock and percolation that the cars were retrofitted with electric pumps - and after a certain date they started coming from the factory with electric pumps as standard equipment.

When they were retrofitted with the kits supplied by Nissan - the Dealer's installed a relay. See attached image.

Before the kits were available - most people just put a jumper in the harness under the dash - and installed the electric pumps in the rear. {no relays or safety shut-off's}.

If you have 12volts at the HOT wire in the rear - and a good body ground - the pump should work fine. If a shop installed a relay - and installed a new wire - that should work just fine - as long as you have 12Volts on the hot wire - and a GOOD BODY GROUND.

As I recall - there is a body ground on that rear harness - on the right side, inside the car {not certain of that - it might be outside the cabin?} ... but it sounds like you have a floating ground ...I'd make sure that you have a clean body ground from the pump - and clean grounds in the engine compartment {from the battery to the body}.

[ATTACH=CONFIG]56243[/ATTACH]

Not to steal the thread; just one question: I have a late 73 Jul production car; it has both the electronic pump and the mechanical pump. Was this how they came?

[conedodger]

Ok, that's frustrating. I ran a 12 gauge wire from the fuel pump to the + side of the coil with a 20amp fuse just before the coil. Nada... Ground is local to the pump.

[Stanley]

Hope this helps. The wire attached to the bottom of the pump is the ground. It's about a foot long and attaches to metal. The one in the middle is the power wire. Took it (the power wire) off the pump to clean the connection which was a mistake, it's sorta not removeable. Stock pump on my 73. Looks better since the photo with black epoxy paint. Not hooked up yet.

[conedodger]

Thanks Stanley... But mine's not stock. It is using an RX7 pump that worked fine before I undid a hack and put in a MSA bladed fuse box...

[conedodger]

I'm up and running. Turns out my MSD was eliminated by the recent install of the bladed MSA fusebox. So, I wired it up stock. 8)