I'm wiring an electric pump on my car and some people say I need a relay? Does anyone know where I can find a diagram on how to wire this up.. As always guys thank you so much for the help. Scott in KY
you may or may not need a relay, depends on what kind of pump it is, where it's located, etc. This should work.
I've run them both ways but feel a relay is better. It puts less of a load on the switch if nothing else. Don
One of these three terminal switches can do that. The terminals are marked I S P and connect to ignition, starter, and pump. With a relay, you'd connect I to the fuse box, S to the purple starter wire, and P to the relay coil (terminal 86 on the relay in the drawing above). The way the switch works, it connects S and P when there is no oil pressure, and it connects I and P when there is oil pressure. So it sends power to the pump when you're cranking the engine, and once it gets oil pressure. http://www.rockauto.com/catalog/x,carcode,1056787,parttype,4588
I have mine set up pretty much like the diagram that Squirrel put up without the relay. I havn't fired teh car up yet though.
For a street car with a regular carburetor I don't believe that a relay is required. I've had plenty of them on several cars over the years and never added a relay. I believe in the KISS system. To me it's just something else that could fail out on the road. I'm still stuck in the 60s. The big question was always do you need a toggle switch or just wire it up to the ignition switch. I always just wired it to the run terminal so that I wouldn't forget the switch.I wire my cars like I did back then. I don't recall any epidemic of problems. Nothing that I am aware of has changed to make it unsafe today. It was plenty safe back then and I'm a hotrodder. I don't sell relays for a living or fancy wiring harnesses that have liability issues that started all the hotrod fuel pump relay issues. JMHO
Do what Squirrel said, some of the small pumps don't need a relay though. If it was mine I would keep the mechanical pump. You will get tired of the electrical pump noise, and of having another component that could just die. Make darn sure you have a very good filter on the inlet side of pump, takes less to jam them up than you would think.
Depends on the pump, but I wouldn't run anything smaller than 14ga if you are not going to use a relay. With the relay, only the load side (battery to pump) needs to be that heavy. Bigger pumps obviously need bigger wire. The relay switch side can be 18 or 20 gauge.
Although I'm not stuck in the 60's like "tommy", I too believe in the KISS system. I run a Holley "Black" pump with NO relay and NO problems at all. I've got a buddy that runs an original '67 Pontiac Firebird S/S car with 2 pumps and no relay. Now I'm not going to throw the "traditional" card at anybody but pro drag racers on up to the 90's won races without a relay. WHY NOW?!?!
I would believe this is the wire harness manufacturers way of saying this wire is to be used for the switch side of the relay and not directly to the pump. I agree with racer statement above and would run the relay. TR
I recently wired a car with an E-z wire kit .ran there fuel pump wire thru a hidden toggle switch to the switch side of the relay,so I could do other testing with the key on without the pump running. use a relay the pump will work better .
Having a toggle switch in the wire from the ignition switch to the electric fuel pump is a good idea for more than one reason. It lets you do things where you need the ignition switch on but don't want the fuel pump on and it is something that might help prevent an unauthorized person from driving the vehicle.
I have never run one either and don't see the point. One company sells like a 30 amp relay for them and I can't understand why you would need a 30 amp relay on a pump that pulls less than 10 amps. I don't run the mega buck pump that moves 600 gph either. I think my biggest pump moves 130 gph and pulls somewhere in the neighborhood of 3 or 4 amps. The street pump only pumps 110 gph and pulls close to the same amperage. I do use a separate switch now days but like Tommy I have had a lot of them hooked to the run pole on my ignition switch. I ran one off of an accessory lug in my fuse box once because I thought it needed to be fused. But that was a one time thing when I just had an AMP gauge short out and I was fusing everything for awhile. Paranoia will get ya every time. That is a big part of my reasoning for the toggle on mine. I don't usually hook it to the ignition switch. I run holleys and I can adjust the floats without the switch on or the engine running. But also if a car goes less than 60 ft in Missouri it is just vehicle tampering. You can make it a little farther than that on the fuel in my float bowls. If someone manages to hot wire my car I want them to get it for grand theft auto and not misdemeanor vehicle tampering. By the way did you know that sex is a misdemeanor? The more I miss it the meaner I get. I just wanted to say that. well off on a treasure hunt. Later gators benno
http://www.jegs.com/InstallationInstructions/500/510/510-12-801-1.pdf Figure 2 is how I have mine run. I did add a hidden toggle switch, just for security. I used an open space on my fuse block for my fuel pump.
Relay,...with the oil pres. switch....Wire it to go direct to pump while cranking. Safety...... 4TTRUK
it took me a while to grasp the concept of using relays.I used to wire things with out, did'nt see the point till a guy proved to me how much power I was loosing going to what ever with the power going thru fuse block, ign switch ,toggle switch then to what ever. rather than going from battery thru relay direct to pump etc., more direct and consistant power to the pump.
No relay but put a fuse between the switch and pump, that way I can pull it when working on the electrical system.
I've always run electric pumps and wire them with power from the fuse block to the switch and from the switch to the pump. Never used a relay, my Holley Red only draws 5 or 6 amps. Never had any problems in 40 years. I'm with the keep it simple crowd.
I ended up with a 5 pin on mine but eliminated the blue center wire. Intact I fired up my anglia for the first time in 8the years.
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