DIY Fuel Prime

[Twinky-Ninja]

To start, this post was inspired by another one of the same topic.. I found it one night while browsing, and couldn't find it since.. So i grabbed the wiring schematics (thanks Defiant) and wired it myself.
Ok, so the basic purpose of this modification is to allow you to prime your fuel pump on demand, with the key to on, and the car not started yet. I have heard various facts on the 1g's stock fuel prime operation, and decided to put myself in control of it.
Background: Ever since I have owned my 1g, the fuel pump has never primed with the key placed to on. I've checked wires, relays, connectors, and the pump its self. Everything checks good. I have upgraded to an adjustable fpr along with feed and return lines, and car takes a few extra cranks to fire up.
The images below are how i wired up this mod. My car has the cruise control knob, and my cruise stuff is removed, making it a perfect candidate for the switch used to prime the fuel pump. (im using the set circuit, the little button on the end) If you don't have this knob, you could use any switch to ground pin 7 of the mpi relay harness, this will trigger the relay, close the fuel pump circuit and prime it. I highly recommend a spring loaded non locking switch, this way you don't accidentally leave it on.
Access to the connectors are very easy.. remove the trim panel under the steering column, and follow the harness going down the the connector. You will want to cut the red wire (pin 8) on the steering column side of the connector. Splice in a wire (extend it), about 2.5 feet long and route it down to the MPI relay (inside the center console under radio) Cut wire 7, its a white wire with a red stripe, now use a splice and splice the wire you just cut back togeather, only now insert the wire you just ran from the steering column into one of the ends of the splice. (of you could buy a wire tap and just tap into the wire going to pin 7) With everything back togeather, you should be able to turn the key to on, and press the set button on the cruise and it will prime your pump for as long as you hold it. Once the car is started, fuel pump operation is completely normal.
As a disclaimer, if something is wrong with your fuel system, you should fix it properly. I am familiar with electrical wiring, and wanted to give my talon a custom touch. if you dont know much about wiring, you may end up doing more harm than good.
Images:

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I'll have a vid of it in action soon.
I hope this helps somebody.
Don't blow anything up, and happy holidays.

dave

 

[eclipsh]

I think you're posting about my old tech article or a thread where it was discussed. The reason it isn't there anymore is for safety reasons. I had the priming system hard wired in and have since removed it. The pump came on as soon as the key turned to the "on" position and stayed that way unless I A) turned the key off B) killed the ground switch for the system. With it set up that way the risk of fire in an accident was much higher since the pump wouldn't turn off. Great job in finding a better solution!

As far as switch choices, if someone could find a switch which was sprung but could also be locked down temporarily it'd be very nice for fuel system diagnostics. I did love having that option in mine.

 

[turbosax2]

Here is how to do the same on a 2g. I posted this on this thread.

We finally got around to wiring up the switch. Since my brother removed his cruise control, we used the cruise control switch on the steering wheel. We used this switch because it is not an on/off style switch, you have to hold the switch down for it to remain activated. So to turn the fuel pump on, the key must be in the accessory position and you pull the cruise switch toward you (the "cancel" function).

To wire the switch, I just traced back the wires from the switch that run along the steering column. Underneath the dash is a white connector that connects the switch wires to the harness. There are three wires on the connector. I cut the red wire and taped off the harness side of the wire. The switch side of the wire gets spliced into the power wire for the fuel pump relay (the wire is black with blue stripes). I spliced into this wire where it runs underneath the drivers side kick panel. There is a large bundle of wires down there, just cut the tape that holds them all together and pick out the fuel pump relay wire and splice the new wire into this one. Sorry, I don't have any pictures.

Although this switch would still work if the car stalled, I think it's pretty safe because it's not an on/off style switch. I'm still going to look for a better wire to power the switch from the ecu that loses power when the car stalls when I get time.

 

[Twinky-Ninja]

Yep, thats the thread i was talking about Eric.. Good call on the whole idea. Here's the vid. *Edit* Also, just a note eric.. By doing this your not supplying power to the fuel relay, your providing a ground, so you probably wouldn't want to run 12 volts to that wire.. If anyone is worried about being able to manually prime their pump when they stall, I would tell them to fix their car first..heh

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