Gravityman Posted May 27, 2005 Share Posted May 27, 2005 Hello Fellow Subaru Freaks I was wondering if anyone knows what the operating voltage of the XT6 or XT4 turbo fuel pump runs on. I dont know if I should have done this or not but I tried hooking it up directly to my battery, I saw a spark but heard no type of pumping noise. Curious but is there anything else that needs to hook up to this pump to control it or will a continious voltage start it and keep it going? Thanks for the help! Quote Link to comment Share on other sites More sharing options...
idosubaru Posted May 27, 2005 Share Posted May 27, 2005 12 volts at the pump. if you run a complete circuit to the battery it should come on. if you ran 12 volts from the positive side and got nothing then it's possible that the ground side of the fuel pump circuit is where the ignition is to turn it on. (never had to mess with the fuel pump circuit myself so i haven't done it). in that case, you'll just need a good ground (ground wire to the battery would certainly do the trick) to get it to kick on. make sense? do you want it powered all the time or just for testing? because running a wire directly from the battery means it will be powered all the time, even when the car is off. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted May 27, 2005 Share Posted May 27, 2005 If you have a good ground, and if it does indeed spark when you try to connect 12v to the pump but still had no pump action, it is possible that the pump has seized. The spark indicates a completed circuit (though maybe "completed" to the ground connector... :-\ ), and if the pump has seized then the motor has stalled, drawing its max current. Just some very negative thoughts... Quote Link to comment Share on other sites More sharing options...
Gravityman Posted May 27, 2005 Author Share Posted May 27, 2005 Ahhhh...... Ya that would SUCK, not pumping! I was checking out my chiltons wiring diagram which is crappy at best after using AF technical orders (F-15E wiring diagrams on crack!, try to follow a wire through a $60M Jet, Fun!!!) ANYWAY... There are 2 wires coming from the pump. One wire (Black) goes to the MPFI control unit (wire is marked NCA, not quite sure what NCA means, I think its a metal shielded wire). The other (blue) goes to the fuel pump relay which is linked to a "Hot at all times" wire and a fusable link. I think it would work w/a constant 12v. I am using it to test my injectors for fuel flow, cc flow, and cleaning. I will retry and let you know. Mabe it just needs a good droping to unsieze it! Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 28, 2005 Share Posted May 28, 2005 Working on an F-15E, wouldn't that be fun. I would really like to check out the RF systems on that bird. Along with a test flight. The black return wire you mention is usually controlled by the ECU. It will turn on the circuit to make a ground connection and turn on the pump. Tieing 12 volts to the pump should make it run. If the motor doesn't turn then something is wrong. Tapping on the pump has helped some folks get it going. Quote Link to comment Share on other sites More sharing options...
Gravityman Posted May 29, 2005 Author Share Posted May 29, 2005 Well, I should have tried this before posting a thread, but the pump works. Who would have guessed that the BLACK wire is ++POSITIVE++, and the BLUE which later in the wiring actually hooks to RED is --NEGATIVE--. Kinda basackward ya think SUBARU??? Anyway, I got the pump working pulling 12vdc directly off of the battery. The only thing is I hope that there is not too much current with it directly hooked to the battery. Anyone know if this is ok??? Thanks! Quote Link to comment Share on other sites More sharing options...
NorthWet Posted May 29, 2005 Share Posted May 29, 2005 There are safety isssues with this method, in that a direct connect (user-switched, I assume) means that the pump will pump fuel regardless of situation or attitude (of the car, that is). This is a real fire hazard. I know that lots of people do it, but that does not mean it is a safe practice. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted May 29, 2005 Share Posted May 29, 2005 there is no issue in doing that. the critical point is that it's a 12 volt power source, that's all that matters. it will only draw (V/R) amps of current where V is your 12 volt power source and R is the internal resistance of the pump. what kind of wire won't matter. may risk burning the fuel pump up in a wierd situation, like if the voltage regulator malfunctions on the alternator and it's hooked up to the same battery....and there's not relay or fuse in between to fail before the pump. if you want to get technical about current, any resistance in the line is in addition to the resistance imposed by any device on the same circuit (the fuel pump and wire have a combined resistance of the fuel pump resistance plus the resistance of the wire). wire diameter increase = resistance decreases = current increases wire length goes increase = resistance increases = current decreases using a larger diameter wire will cause a slight decrease in resistance (assuming you're comparing similar grade, material, manufacture and quality wire). but this is only a technicality, very minor and won't hurt anything. the fuel pump is designed to work on a 12 volt power source, that's the key. Quote Link to comment Share on other sites More sharing options...
ruparts Posted May 29, 2005 Share Posted May 29, 2005 Hi, It runs on 12 v, its ok to do it as long as you unplug it from the harness and no chance to have voltage into the system from the pump area. These will run forward and backward , be sure . Hello Fellow Subaru Freaks I was wondering if anyone knows what the operating voltage of the XT6 or XT4 turbo fuel pump runs on. I dont know if I should have done this or not but I tried hooking it up directly to my battery, I saw a spark but heard no type of pumping noise. Curious but is there anything else that needs to hook up to this pump to control it or will a continious voltage start it and keep it going? Thanks for the help! Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 29, 2005 Share Posted May 29, 2005 As stated, the motor is designed to run on 12 volts. Motors will draw more current if there is excessive load on them that causes them to slow down. Counter EMF from the motor windings causes the current flow to slow down. If the motor is slowed down somehow by force then there is less counter EMF and current rises. This can kill a motor if it goes on too long. Quote Link to comment Share on other sites More sharing options...
Gravityman Posted May 29, 2005 Author Share Posted May 29, 2005 Thanks all! I was actually wondering this because I am using the pump as an injector flow tester. NOW my problem is the pump runs but It wont pump water. I picked up the pump from the junk yard so I wonder if its just clogged. I filled a fuel line up half way with water gave it power to pump and then with the water in the line I used my air compressor to force the water through. In this attempt which failed I was trying to force any blockage out but it didnt work. Does anyone else have any ideas to clean a clogged pump? or am I retarded? Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 29, 2005 Share Posted May 29, 2005 After looking at your post #6 I think you may have the polarity to the pump backwards, so the pump is drawing in fluid. Did you try reversing the leads to the pump to see if it would pump then? My manual (for a different model) shows the blue lead for the pump going to the positive side. Quote Link to comment Share on other sites More sharing options...
Gravityman Posted May 30, 2005 Author Share Posted May 30, 2005 Yep dude. When I had the opposite polarity it just sat their and looked at me like i am a retart saying "hey retart change polarity"! I did and the pump turned on and but no pump pump! ????????? There was a little bit of water coming out but definatly not 60-70 psi more like -3psi. I will make my way to the JY (junkyard) and find a replacement. That should be the best way to go! Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 30, 2005 Share Posted May 30, 2005 Well, hopefully the next pump is better than that one. Quote Link to comment Share on other sites More sharing options...
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