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JAG1

Lift Pump Wiring questions

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I have two more stock Lift pumps to burn up before I get a Raptor. Anyhow, would it be okay to use an 85 amp continious duty mechanical type relay (you know the old style with contacts inside) instead of the solid state ones you guys are using? Wanna run the pump off the batteries or the Alternator like some are doing, but, don't understand.... doesn't the alt put out too much amps or volts till it goes thru the volt meter first?? Where did you come off the alt?Shows how little I know, but may help someone else also.T.I.A.

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i would put those stock lift pumps in the garbage can. Spend the smaller amount of cash to get the raptor.using the stock lift pumps you seriously jeopardize killing the vp of which will cost you no less than $1200, most are over $1300-1400. I urge you not to use the stock lift pumps. I dont think you will find a single person on this forum that has a second gen with vp using stock lift pumps, or they are currently switching to a aftermarket lift pump.

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I have two more stock Lift pumps to burn up before I get a Raptor. Anyhow, would it be okay to use an 85 amp continious duty mechanical type relay (you know the old style with contacts inside) instead of the solid state ones you guys are using? Wanna run the pump off the batteries or the Alternator like some are doing, but, don't understand.... doesn't the alt put out too much amps or volts till it goes thru the volt meter first?? Where did you come off the alt? Shows how little I know, but may help someone else also. T.I.A.

I might be wrong but i believe the Raptor comes with a wirng harness and relay. My AD did. I connected right to the supply on the back of the alternator and grounded to the braket. You would get the same power if you cnnect to the battery or the PDC like some do. Wether the other relay would work or not i dont know.
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My AirDog 150 as comes with a relay, fuse, etc... Allow you to hook up the pump without putting the load of the pump on the ECM... Please don't wire it to the batteries either. There is a nice mounting stud in the the PDC box where you can hook up everything...

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I might be wrong but i believe the Raptor comes with a wirng harness and relay. My AD did. I connected right to the supply on the back of the alternator and grounded to the braket. You would get the same power if you cnnect to the battery or the PDC like some do. Wether the other relay would work or not i dont know.

my raptor 150 has a harness that runs power from batteries to the pump via a relay controlled by the ecm plug just like airdog.

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Need to can those 2 stock pumps I have. Like to hear opinions on any of the good aftermarket brands?Thank you all for finally convincing this stubborn old guy on them pumps. :cookoo:

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Thanks Mike.:thumb1: I already have the big lines, draw straw and relocated oem pump so it's a breeze to install the new pump. I even have 1/2'' inch shut off valves in the fuel lines, one on each side of the pump for easy change out :thumbup2: no reprime.:hyper: No drain back to the tank either:tease:.That pump is a little bit of money. have to wait a few weeks.

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I moved my raptor back by the tank could I just make my own harness?

Good option to do to your truck. You can make your own harness but, may harm the ecm if you accidently hook up the wires backwards. I just would make sure it's correct It's best to have the ecm wires activate a relay and the pump then gets it's power directly from the power distribution panel or center. That way it won't burn up the expensive ecm if the pump decides to go bad. Read all the above posts carefully and you'll begin to understand how others did this. I do not like powering off something that's as sensitive as the ecm. It's $500 bucks to replace it. Although I think there is a way to set up the truck so you no longer need an ecm. Not sure about that yet... still trying to educate myself :smart: I only know from Mike that it's better to get the power for the pump from elsewhere.

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while i need to finish it i have the ultimate FASS guide under general Cummins/ Fuel systems

I looked for your article but cannot find it. Being that I'm new to this site an all :wow:

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any body got a digram of a wire harness I'm pretty good at wiring things up i think adding a relay would help a lot since i moved my pump back by the tank.

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any body got a digram of a wire harness I'm pretty good at wiring things up i think adding a relay would help a lot since i moved my pump back by the tank.

If you go digging around by where your lift pump is (on the block) you will see a two pronged cord, run the positive to a relay the ground to the other side using a real relay set up, then power directly off the PDC. I'll make note on adding this to my FASS guide when i get to finishing it this week.
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If you go digging around by where your lift pump is (on the block) you will see a two pronged cord, run the positive to a relay the ground to the other side using a real relay set up, then power directly off the PDC. I'll make note on adding this to my FASS guide when i get to finishing it this week.

I am a little lost on what you are saying i know where the two wires are on the side of the block I tied into them to run back to the raptor not sure how to wire a relay into it the last thing I want to do is burn up my ecm. if some body had a digram it would help a lot

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I am a little lost on what you are saying i know where the two wires are on the side of the block I tied into them to run back to the raptor not sure how to wire a relay into it the last thing I want to do is burn up my ecm. if some body had a digram it would help a lot

You take the ECM positive and run it to the relay, that will then power the coil spring, to open the switch inside the relay, this switch then has the positive coming from the battery(or PDC), and the other side goes to the pump, the negative goes to the ground. Here is a link to a site with a relay explaining how it goes http://www.r1200gs.info/howto/relay.html If i was not tied up writing up this interrogatories i would have shot a how to video by now.

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If you go digging around by where your lift pump is (on the block) you will see a two pronged cord, run the positive to a relay the ground to the other side using a real relay set up, then power directly off the PDC. I'll make note on adding this to my FASS guide when i get to finishing it this week.

What he's saying is using the wires that were normally hooked to the lift pump as the ones to activate the relay. When the ecm tries running the pump it will click on the relay instead and then the pump will be connected directly to the batteries inside the PDC box. This way the ECM is isolated from possible harm from high amperage draw if the pump goes binding up.. Mike the mopar man has taught this to all and me too so just repeating what he said. My trouble is I don't trust electrical stuff and want to do this without a relay, more simple =more reliable :cookoo::)

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What he's saying is using the wires that were normally hooked to the lift pump as the ones to activate the relay. When the ecm tries running the pump it will click on the relay instead and then the pump will be connected directly to the batteries inside the PDC box. This way the ECM is isolated from possible harm from high amperage draw if the pump goes binding up.. Mike the mopar man has taught this to all and me too so just repeating what he said. My trouble is I don't trust electrical stuff and want to do this without a relay, more simple =more reliable :cookoo::)

what you are describing is the typical wiring setup for a FASS/airdog system. You put the relay on the positive side, and then the Positive voltage from the ECM powers the relay, thus opening the relay up and allowing electricity to flow to the fuel pump. I find that its really hard to kill a relay, and the voltage shouldn't go backwards as they will not be inter connected, so if the fuel pump goes nuts, it won't effect the ECM, just batter or PDC (which ever you hook it up to, The ECM positive runs at i believe 8 volt, or 8 am, (idr), you need to run on 12v@ 20 amp as the FASS 95 runs on 20-25 amp as it has a 30 Am inline fuse in it. Running a full sized fass/ airdog pump will burden the power from the ecm.
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ok that makes sense to me now i was not sure what to do with the other wire i am guessing that you just do not use it, and would you just ground the punt to the frame?

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ok that makes sense to me now i was not sure what to do with the other wire i am guessing that you just do not use it, and would you just ground the punt to the frame?

I'm still getting this idea together myself, more so now that I hear relays are more reliable. I think there is a ground prong on the relay for the negative wire from the ecm which normally would go to the negative side of the pump.

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A relay needs positive and negative to activate the coil, much like anything else. You can't run something with just positive or just negative. The schematic on top of the relay will show a coil symbol and have a connection on either end of the symbol. Those are the ones that get the positive and negative from the ECM to activate the relay. It doesn't matter which one goes where, as long as you end up with positive on one side and negative on the other, it will turn on.

Now the other part of the relay is what it switches on and off. There will be another symbol that shows a light switch looking thing that is not connected or "normally open". It will look like this. Posted Image

You can see that 85 and 86 are the coil. 30 and 87 are the normally open contacts, you can see the "switch" looking thing between the connections with a dashed line going to the coil showing that it pulls the switch closed to connect 30 to 87. If you have any doubts just show us the schematic of your relay as some are different looking. Anyhow, you hook the PDC positive to one contact and the pump goes to the other contact. Doesn't matter which, it's either connected or disconnected so it doesn't care what it's connecting or the flow of current. Usually 30 gets the power and 87 is the accessory. When the relay gets power, the coil closes the contact between the PDC and the pump so the pump turns on. This does leave the negative of the pump in question, ground it to the frame.

If your relay looked like that, an example would be hook the ECM positive to 85, ECM negative to 86, PDC to 30, and Pump to 87.

Some relays have an 87a, this is a contact that is normally closed, meaning the contacts are closed any time the relay doesn't have power, so don't use that contact.

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