Okay this is seriously pissing me off here, i have the ATI inline pump that came with my procharger, i cant for the life of me get the damn thing to turn over when i turn on the ignition, i know the pump works, when i hot wire it it comes on (the power and ground are good), but not through the relay. I know the relay itself is good, ive tested with about 4 diffrent relays that i know work, still no go. I have the relay run inline with the grey wire from the fuel pump, and the fuse is good. All i get when i turn on the ignition is the in tank pump.. I have it wired exactly like the manual says...WTF ! any ideas ?

 

The grn/blk wire from the ecm "turns on" the in-tank fuel pump relay... maybe the inline pump relay is wired wrong or the ecm cannot supply enough power to trip both relays (depending on how it is wired). just my guesses.

 

Im pretty sure in the later years GM changed the wiring colors, i was told grey was the replacement from the grn/black combo ?????

 

I know its grn/blk in my 92RS, my brother's 88 firebird, and a 91 TransAm harness that I have.

 

i have black purple and grey wires, i dont see a green, maybe ill hook it to the black and see if that helps...

 

Why don't you ohm the wire out and see what it is and where it goes.
You could smoke your harness (or worse) by just hooking things up "to see what happens"!

 

black purple gray is probably the cooling fan.

look for orange orange green and i think gray black or red

 

Like i stated before i only have black,purple, and grey going to the in tank fuel pump connecter under the car, from what im reading it seems everybody has diffrent color wires.

I dont know how to do this, i know it involves a multimeter but thats it, can you explain more s24 ?

 

the grn/blk wire I'm talking about goes to the fuel pump relay on the firewall next to the brake booster.

If the inline pump came with its own relay, then the grn/blk wire can be used to trip the coil in the inline pump relay to run the pump after the car starts. A different wire does the fuel pump priming.

Where are you mounting the inline pump?

 

I have the pump mounted under the car near the rear axle (ATI recommended the closer the better to the fuel tank) so basically i have it setup just after the fuel filter. According to ATI's instructions i ran a power wire from the alternator to the relay, i have the pump and the relay grounded off on a bolt that holds the inline pump mounting bracket, one wire that splices into to the fuel pump harness at the top of the tank. (this is the grey wire i wrote about above) Again this was all recommended in the procharger installation manual... Thanks for your help so far guys

in fact i just found a picture of a similar installation, the red circled harness is what im splicing into, suposedly this harness runs into the fuel pump relay mounted on the drivers side firewall...

https://www.thirdgen.org/forums/atta...0001653_lr.jpg

 

Had the same problem initially... Ended up putting the pump on the shelf and getting a Walbro 255 intake pump..

 

It sounds like they supply the inline pump with voltage from the alternator.
Did you check that the place where you connected the gray wire and ground wire for the relay coil is correct. If the two wires are backwards it will try to keep the relay contacts open. Maybe the supplied diagram is wrong.

Take the relay OUT OF THE CAR and put an ohmmeter across the alternator terminal and the inline pump voltage terminal. Then connect 12V to where the gray wire would go and ground the other terminal you have connected to ground in the car. If the ohmmeter doesn't show continuity then swap the gray wire and ground pins and see if you have continuity then.

Overall, you should have 4 terminals. One to Alternator, one to fuel pump voltage, one to gray wire (to turn on the relay), one to ground.

 

The grn/blk wire provides a ground directly from the ECM for the stock fuel pump relay. DO NOT use this for other relays along with the stock UNLESS you know how much electrical current the ECM driver can handle. Since you don't know the spec, a fried ECM could result depending on which relay is used.

The better method is to use the gray wire for power to the new relay coil and ground the other side of the relay coil. This puts about .1 amps ore less of load on the wire feeding the stock pump which is in the 5-10 AMP range. The contact sides of the relay is connected to battery or ign. and the other side goes to the new fuel pump.

 

You can do this manually if you would like.. I have attached simple wire schematic also using a Bosch 30/40 amp relay and Fuse Holder with a SPST throw switch.

 

I cango look at my harness. I haved a t rex inline under the rear of the car also. And I tapped into the factory harness for power. I didnt tap in for ground. I used a new ground when I mounted the pump.

If I was you though Id run a hot wire kit like racetronix sells. This way you get a solid 14v to the pump.

Get yourself some 10g wire an 40 amp replay. You can make this harness and adapt it for the inline pump.
http://www.racetronix.com/product/RX...98-FPWHG-2.jpg

 

If the feed for the pump is from the alternator then it is "hot wired".

The "hot wire" kits pull the voltage from the alternator and depend on the drop from GM changing the wiring harness after the 1970's. My 255lph Walbro sees 14+ volts all the time with how I have it wired.....from the alternator before the engine and acc. voltage drop.

 

One other thing. The ECM turns on the stock fuel pump relay for a few seconds before engine start and then it turns off. It turns back on when the engine is started. Therefore, the inline pump will do the same.

If you just have the key on without the engine running then the inline and the stock pump will not run after the first few seconds of key on. Maybe you think it should run under this condition?

 

Ok guys what do you think about doing this, Ive decided that having a bunch of wiring underneath the rear car is kinda stupid anyway so here's what i propose... Move the relay into the engine compartment, run a power to the relay, ground off somewhere, run a wire to an ignition source that comes on when i start the car, and run the other lead directly to the pump underneath the car using the wiring i had previously used as the power wire for the relay. At least then ill have everything in one spot, safely underneath the hood away from water and such.

 

Take a look at one of previous Posts.. I have attached a wiring schematic so you can do that. That is a great way to do it.

 

Where would be a good place to tap into thats underhood for an ignition source ?

 

its not under the hood, but I've used the fuse block for stuff like that in the past. there are spots that you can plug in a flat connector.

 

That will work, but remember that the stock pump is trying to push fuel through a non-running pump during the fuel prime during key-on before the engine starts.

You want the relay under the hood and not under the frame. I would still tap into the gray fuel pump wire under the hood near the stock relay for power to the inline pump.

 

Hey fellas,

I got it up and running, i moved the relay to the engine bay, re-wiried everything, protected it from the elements and it runs perfectly, thanks for all your help in the matter !