Electric Fuel Pump Install

[Jeepin' Pete]

I'm in the process of installing an electric fuel pump on my '90 Grand Wagoneer. I'm going with a Holley Red pump and a Revolution electronics fuel pump controller. I'm also doing the pickup method outlined here: viewtopic.php?f=35&t=16478 I'll try to put up some pictures soon.

I do have a few question:
1) The mechanical fuel pump had a return line. I don't see how I would reuse this, do I simply remove it? The return line on the fuel filter has its own hard line running back to the tank
2) The wiring instructions for the fuel pump controller are here: http://revolutionelectronics.com/12003- ... tion-2.pdf
What is a good source for the switched 12V? I'm putting the controller in the engine bay and would like to not run a wire through the firewall to the
fuse block if I don't have to.

[superdave]

I'm preparing to do the same on my 77 and was getting ready to figure out where my switched 12v would be. Looking forward to hearing other's ideas.

[Jeepin' Pete]

Here’s some pictures:
I was surprised by a relatively new aftermarket sending unit - thanks P.O.! Here’s the whole thing with the filter sock.

I rented the SAE flaring tool from AutoZone to make a 5/16 flare to keep the fuel line and filter sock from sliding off.


Definitely not the best flare, but it will work! This is the whole assembly:

It should be located in the lowest part of the tank to pick up all the fuel.
Again, all credit goes to acct21, I’m merely copying what he did.


Sent from my iPhone using Tapatalk

[letank]

I'm in the process of installing an electric fuel pump on my '90 Grand Wagoneer. I'm going with a Holley Red pump and a Revolution electronics fuel pump controller. I'm also doing the pickup method outlined here: viewtopic.php?f=35&t=16478 I'll try to put up some pictures soon.

I do have a few question:
1) The mechanical fuel pump had a return line. I don't see how I would reuse this, do I simply remove it? The return line on the fuel filter has its own hard line running back to the tank

The return line starts at the fuel filter by the valve cover -unless doing an EFI system

here is the new location of the fuel filter



and the routing next to PS pump



As for the sock in the gas tank, I ditched it and put an extra hose length to about 1/8 from the bottom of the tank, put a fuel filter before the fuel pump and still kept the one in the engine bay

2) What is a good source for the switched 12V? I'm putting the controller in the engine bay and would like to not run a wire through the firewall to the
fuse block if I don't have to.

I picked up one the unused switched post on the fuse panel, it depends on the year model, add an inline fuse as most are unfused

[agentknowles]

I'm as well having a heck of a time finding the 12v switched power. The one I used is sending feedback from the alternator and not allowing the car to turn off. So Frustrating, any specifics would be great. I have a 85 Grand wagoneer.

[tgreese]

Regarding the return line -

Yes, it originates from the fuel filter and runs back to the tank. Its purpose is to circulate fuel from the tank through the lines and back to the tank, reducing the temperature of the fuel. You can read about it in your TSM in the fuel chapter. You could leave it - it's just an orifice in the fuel filter that allows a limited amount of fuel from the pump to return to the tank. I don't understand why this is confusing - suggest you reuse the original fuel lines, except to bypass and block off the original mechanical fuel pump.

Regarding switched power, I presume you have added a fuel pump relay that is switched on by the ignition switch. The alternator is connected to the ignition switch, just like anything else that has switched power. There is a resistance wire between the alternator and the ignition switch that normally prevents back feeding. Once the alternator starts self-generating, it will hold that connection high (ie full battery voltage). The resistance wire limits current enough to starve the ignition when you shut the key off and the engine will stop. Likely this is enough current to keep your relay energized, which holds the fuel pump on and back-feeds more current to the ignition switch.

You need a diode between the alternator and the ignition switch. This will allow the alternator to boot-strap from the ignition like it's supposed to, while blocking back-feeding to the ignition. If you need to, you can add diodes to your relay circuits so they also cannot back-feed into the ignition switch.

If you want, trace out your circuit on a piece of paper, scan it or take a pic, and post it here. I will look at it and comment.

[letank]

for the fuel pump feed, I used the slot for the AC on the fuse panel... Not having an AC is easy, but if you have AC, there are other available slots on the fuse panel, or add a jumper

[tgreese]

Looking at the diagram for your controller, there are two wires that are connected to 12V. The red wire just controls the controller; it does not supply power to the pump. The purple wire powers the pump, and it can connect to the battery.

Look at this page of the '90 GW wiring diagram: https://oljeep.com/gw/elec/90_numeric/9 ... Page-7.jpg
I suggest you connect your red wire to splice 11 that will be somewhere in the harness under the hood. If you have run-on problems like the other poster above, you will need to add a diode between the alternator and splice 11, to prevent back-feeding from the alternator.

[Stuka]

I'm as well having a heck of a time finding the 12v switched power. The one I used is sending feedback from the alternator and not allowing the car to turn off. So Frustrating, any specifics would be great. I have a 85 Grand wagoneer.

Are you using a relay? The relay would be fed off the battery, but it would be switched on by the switched power on the other side of the ignition switch. If the ignition switch is turned off, the relay opens up and cuts power to the pump.

[tgreese]

I'm as well having a heck of a time finding the 12v switched power. The one I used is sending feedback from the alternator and not allowing the car to turn off. So Frustrating, any specifics would be great. I have a 85 Grand wagoneer.

Are you using a relay? The relay would be fed off the battery, but it would be switched on by the switched power on the other side of the ignition switch. If the ignition switch is turned off, the relay opens up and cuts power to the pump.

Allow me to amplify two points in Stuka's comment.

First, the resistance wire between the ignition switch and the alternator quite likely will supply enough current to hold any fuel pump relay closed. Once the relay is energized, it takes much less current to keep the contacts closed than it does to energize. To fix this, you add a diode between the alternator and the ignition switch. A diode here is the answer to many such problems caused by the alternator backfeeding into the ignition switch.

Second, the fuel pump power should come from the battery, not the ignition switch. This is important to prevent the backfeeding condition described above. Separate the fuel pump power from fuel pump control. Also, the ignition circuit may not have the capacity for the added load of a hefty electric fuel pump.