My RX-7 fuel pump install in the '71 240Z

[ezzzzzzz]

After reading many posts on the subject I decided to go with the RX-7 pump too. The original pump worked fine but was very noisy. The PO had wired that pump directly to the battery through a switch under the driver's seat! Not safe at all! I fabbed up a bracket to mount the RX-7 fuel pump in the same location as the OE pump. The wiring was already in place. The pump was wired black/white to green and black to black. My pump has a 90 degree inlet and straight outlet but replacements at the local parts store has 90 degree fittings at both ends. There is a green wire (power) and black wire (ground). The ground is located on the rear frame and is used for the rear lights too. My green wire had a bullet connector in it at the passenger footwell just below the glovebox. It tied into a small harness that ran within the dash and terminated behind the radio. There is a small two blade T-type connector with two leads (green and black/white). The black/white is power from the ignition with the key in the run or start position. A factory fuse holder plugs into the connector completing the circuit (you could easily install an aftermarket fues holder if the original isn't there). I chose to use an oil pressure switch to stop the fuel pump if the engine stopped running or oil pressure dropped. In reality, it is only to reduce fuel spillage in a wreck, not save the engine as it would continue to run until the fuel bowls emptied anyway (unless you're upside down :stupid: ). Initially, I hoped to use a 280ZX sender (idiot light switch) but it opens with fuel pressure turning off the dashlight (duh). I found several GP Sorenson switches that would work (OPS46 OPS47, OPS50, etc.) I picked the OPS47 because that's what was available. A 1/8 npt tee was installed in the block using a small double-ended nipple. I ran a 1/8 bsp die over one end of the double-ended nipple to fit the block. I notched the threads (to simulate a tap) on an old OE sender to cut threads in the 1/8 npt tee for the OE sender. The OPS47 threads into the side port of the tee. Back at the footwell I installed a 12v bosch relay. A fused 12v lead (power block installed by me) goes to #30. The bullet connector is separated and the green wire going to the pump is connected to #87. The OPS47 is connected to #85 (another wire installed by me) and the other bullet connector green lead from the dash is attached to #86. When the ignition is on and oil pressure is available then the relay closes providing 12v to the fuel pump. I will add an inertia switch (in case of an accident) in the rear near the pump. I will also be installing a simple "momentary on" switch to bypass the oil pressure switch allowing for priming the carbs if needed. Based on my 11/70 build date I'm assuming this OE wiring is available for most early S30's.

[madkaw]

Thanks for taking the time to write this up ezzzzzz. I am contemplating the same set up but never have seena "how to" write up! Did you find a junk yard pump or a new one, how much was the new if that was the case?

[ezzzzzzz]

I bought two pumps off eBay for a small sum. One of these siezed up shortly after being installed. The other is doing okay. I priced these at Napa, Autozone, and Advance auto parts. The low figure was about $80 and the high was +$100. I bought two more used pumps for a song off eBay yesterday. If all of these fail then I'll pop for a new unit. These pumps are relatively quiet and provide the proper pressure without a FPR. I still have a FPR in line after the filter set to 2.5 psi though. I'll take some pictures and post them up.

[beandip]

I this vary mod 4 years back only I used a pressure switch that has two male blade connectors I think it was $6.00 at nappa. It activates the fuel pump at 5 psi oil pressure . This way if I need to by pass it I simply connect the two female connectors with a modern fuse which I keep in the glove box. I paid $15.00 for my pump at the bone yard. Three years and all is good. They put out 5 psi. My Z has all '72 wiring and it is prewired from the factory for a electric pump . There is a in-line fuse near the radio that is for this mod. It is on the passenger side of the foot well. The inertia switch I found on a Ford truck in he cab up by the heater . Simply wire it in line with the fuse. I have tried this pump on a stroker engine with triple Mikuni's and it supplied them with no problem. Do install a in-line filter before the pump to safeguard it . Gary

[ezzzzzzz]

I have not installed the pre-pump filter but intend to do so. The pump will appreciate the absense of any debris. My fuel tank was in immaculate condition but I had it cleaned and sealed internally since they are hard to come by. The outside was stripped, rust proofed and sprayed with several coats of undercoating prior to reinstallation. I got my inertia switch from a Ford Taurus and will wire it into the green power lead back at the rear panel. My oil pressure switch is similar to yours. The fuse idea is great although I'll probably still install a simple SPST switch under the dash to provide a bypass to the pressure switch for priming the carbs from the driver's seat.

[koolhof]

Question = I removed my mech fuel pump and installed a larger electric one in back. I noticed that the circuit will not become hot until the engine is running. Were is the switch that controls this circuit? You mentions a pressure switch, oil or fuel pressure. What is SPST switch??

[beandip]

The pressure switch is just a simple one . The automotive industry has used them for years for stoplight switches also. When the fluid becomes pressurized the contact close. Just take your oil sender to the parts store , buy a Tee that will allow the sender to screw into it. Ask for a pressure switch that will also fit the tee, and one that activates at 5 to 7 PSI and has two mail spade contacts. You run the switch in the circuit so that pump power flows through the switch when the pressure is up. Screw the tee into the block and you are done . Now this must be for a carburetter engine only . In the event that you run out of gas , just use a modern fuse with two spade connectors and just plug it into the leads to the pressure switch and turn on the key . The power to the pump will fill the carb float bowls and the engine will start. Gary koolhoff , either your pump is drawing a lot of amps or the connections are corroded.

[Pete 73 240Z]

I'm running a 4070 Carter fuel pump on my Weber DGVs now, I have it wired straight from fuse block to pump so it operates when ignition is on. I know I need a inertia switch but should I run another relay?

[beandip]

I'm running a 4070 Carter fuel pump on my Weber DGVs now, I have it wired straight from fuse block to pump so it operates when ignition is on. I know I need a inertia switch but should I run another relay?

I am not familiar with the 4070 pump . as to the relay I would find out how many amps it draws . This is a big factor because of the load put on any switch. One thing with the RX pump is that it is a 5 psi pump but will feed triples with no problem . We tried one on a Stroker with triple mikunis' and it handled them just fine. An inertia switch is something all of these car could use to be safe . Of course those with electric pumps. Had to say that , other wise some one would jump on it . Gary