Wiring inline fuel pump

[Scott Mckenzie]

I need some wiring help for my `64. I want to install an inline fuel pump and know very little about the black art of electrical stuff .  Holley calls for the power side to be wired to an ignition source. Can someone help a fella out ,where can I find a source ? This is going to sound basic but I have to start somewhere 

[KongaMan]

What's the current draw of the pump?  It might not be advisable to connect the pump to just any ignition source, as the pump might overload that circuit.  It may be better to use the ignition as a trigger on a relay, drawing the power for the pump straight from the battery using a dedicated, fused circuit with the proper size wire.

 

As for which wire to tap: where are you going to mount the pump?

[F&J]

The "Holley" tag makes me think it will draw more than a NAPA "Facet" brand low-psi pump.

 

So, I agree on using a relay if needed. (read the amp draw specs) There is a commonly used "Bosch relay" that is simple.

 

On that Holley, I'd want to know if it has too much pressure for a given stock carb.  I thought Holley is a performance pump? Not sure.

 

I use the Napa 1-3 psi on  55Olds with twin carbs.  No pressure regulator needed.

 

.

[carbking]

Along with the relay, it is important that the pump be wired to some safety device, to prevent the pump from continuing to run after an accident. The most common method is to use an oil pressure switch to provide power to the relay.

 

As mentioned by F&J, VERY important to know the design pressure for the carburetor in question. Electric fuel pumps basically have a constant volume and pressure, as opposed to a pump which is engine driven, that will provide volume based on the RPM of the engine.

 

The "law of unintended consequenses" gets much use from the aftermarket installation of electric fuel pumps. Don't let it happen to you. Not trying to talk you out of the electric pump, but (and no offense meant) if you have to ask questions about the installation, it might be money well spent to have the pump professionally installed.

 

Jon.

[KongaMan]

34 minutes ago, carbking said:

Along with the relay, it is important that the pump be wired to some safety device, to prevent the pump from continuing to run after an accident. The most common method is to use an oil pressure switch to provide power to the relay.

Good point.  There are also resettable shock sensors that provide the same function in the case where the car gets hit but the engine continues to run.  A good bet there would be to scavenge one at a junkyard.

 

But about that oil pressure switch...  Do you get enough pressure during cranking to close the switch?  My sense (and this could be wrong) is that most folks who install electric fuel pumps on these cars do so to avoid lengthy cranking after the car's been sitting for a while.  For that purpose, you'd want the pump to come on with the key, no?.

Edited November 7, 2016 by KongaMan (see edit history)

[Jim Cannon]

I put my electric fuel pump on a switch that is spring loaded.  I press it down for a minute or two before cranking, to refill the carb.  Then the engine starts right up.  I do not hold the fuel pump on all the time.  The mechanical pump picks up from there.  If you do this, you do not need a safety switch or relay.  You are taking power straight off the fuse panel fuses that are hot all the time.

 

[carbking]

"But about that oil pressure switch...  Do you get enough pressure during cranking to close the switch?  My sense (and this could be wrong) is that most folks who install electric fuel pumps on these cars do so to avoid lengthy cranking after the car's been sitting for a while.  For that purpose, you'd want the pump to come on with the key, no?. "

 

When I use an electric pump, I use double wiring.

 

(1) For constant use - as described above.....oil pressure switch, relay, pump

(2) For temporary use ie. starting - as Jim described above.....push button switch which is normall off, relay, pump

 

Jon.

[Scott Mckenzie]

20 minutes ago, Jim Cannon said:

I put my electric fuel pump on a switch that is spring loaded.  I press it down for a minute or two before cranking, to refill the carb.  Then the engine starts right up.  I do not hold the fuel pump on all the time.  The mechanical pump picks up from there.  If you do this, you do not need a safety switch or relay.  You are taking power straight off the fuse panel fuses that are hot all the time.

 

 This is what I`m wanting to do. Are you wiring to the fuse panel ? I have no problem with wiring a push button switch I want to know where to get power. 

[Jim Cannon]

4 hours ago, Scott Mckenzie said:

 This is what I`m wanting to do. Are you wiring to the fuse panel ? I have no problem with wiring a push button switch I want to know where to get power. 

 

Yes.  One side of the fuse panel is hot all the time (windows, courtesy lights, etc.).  The other side only comes on with the key (wipers, radio, etc.).  Tap into something on the "hot all the time" side.  Choose a pretty high amp fuse so that you have enough current to run your pump (not a 3 amp instrument panel lights fuse).  Be sure to be on the side of the fuse where the fuse protects you.

 

Disconnect the battery ground cable before you start messing with the fuse panel.  It is easy to accidentally short out against the metal stuff under there.

 

 

[KongaMan]

Even if you are taking

4 hours ago, Jim Cannon said:

I put my electric fuel pump on a switch that is spring loaded.  I press it down for a minute or two before cranking, to refill the carb.  Then the engine starts right up.  I do not hold the fuel pump on all the time.  The mechanical pump picks up from there.  If you do this, you do not need a safety switch or relay.  You are taking power straight off the fuse panel fuses that are hot all the time.

 

I'm confused by this.  If I'm reading the wiring diagram correctly, there are four circuits in the fuse panel which draw power directly from the battery (the others draw from the ACC feed from the ignition switch): clock (2A), dome light (20A), courtesy lights (5A), tail lights (10A).  Are you saying that you tapped into one of these circuits to power the fuel pump?  That is, is your fuel pump protected by the same fuse as the dome lights or tail lights?  Or are you saying you just tapped the red wire from the battery somewhere near the fuse box and use an inline fuse on the pump?

 

As an aside, there's quite a bit of power going through that ACC feed.  Might be a bit easier on the ignition switch if that feed triggered a relay rather than supplying the current directly.

Edited November 8, 2016 by KongaMan (see edit history)

[KongaMan]

5 hours ago, Scott Mckenzie said:

 This is what I`m wanting to do. Are you wiring to the fuse panel ? I have no problem with wiring a push button switch I want to know where to get power. 

The battery feed comes through the bulkhead connector and splits in four directions: ignition switch (10 gauge), fuse box (10 gauge), light switch (14 gauge), lighters (14 gauge).  If you've got power windows, there's a 10 gauge feed for that as well.

Edited November 8, 2016 by KongaMan (see edit history)

[Jim Cannon]

3 hours ago, KongaMan said:

Even if you are taking

I'm confused by this.  If I'm reading the wiring diagram correctly, there are four circuits in the fuse panel which draw power directly from the battery (the others draw from the ACC feed from the ignition switch): clock (2A), dome light (20A), courtesy lights (5A), tail lights (10A).  Are you saying that you tapped into one of these circuits to power the fuel pump?  That is, is your fuel pump protected by the same fuse as the dome lights or tail lights?  Or are you saying you just tapped the red wire from the battery somewhere near the fuse box and use an inline fuse on the pump?

 

As an aside, there's quite a bit of power going through that ACC feed.  Might be a bit easier on the ignition switch if that feed triggered a relay rather than supplying the current directly.

 

I just tapped into one of the fuses that are hot all the time.  I don't remember which one.  My fuel pump does not draw much current.

 

You are correct, running all that ACC power through the ignition switch is a weak point of the wiring.  If I ever get in there, I will rewire that through a relay.  My ignition switch gets hots after the car has been running a while.

 

 

 

[KongaMan]

2 hours ago, Jim Cannon said:

 

I just tapped into one of the fuses that are hot all the time.  I don't remember which one.  My fuel pump does not draw much current.

 

You are correct, running all that ACC power through the ignition switch is a weak point of the wiring.  If I ever get in there, I will rewire that through a relay.  My ignition switch gets hots after the car has been running a while.

 

IMHO, both the ignition and light switches are weak points.  Each could benefit from moving some of its functionality to relays.  If -- as you experience -- the switch is getting hot, that's energy being lost. It's also not doing your switch any favors to have it heat up that much.

 

Have you ever measured the voltage at, say, the blower when it's running on high?  It would be interesting to see how much it's dropped from the battery.

 

It seems that bypassing the ignition switch by rerouting the ACC circuit through a standard Bosch 50A relay should be pretty easy:

- Cut the pink wire between the switch and fuse box*.

- Connect the end from the switch to terminal 86.

- Ground terminal 85.

- Connect a battery feed to terminal 30/51.

- Connect the pink wire to the fuse box to terminal 87.

 

* You might not have to cut it; it might connect to the box with a spade lug, so you can just unplug it.

 

One can probably assume that the individual circuits (save the cigar lighters) are adequately wired, so making the feed to the fuse box more robust should be enough.  However, the battery feed from the horn relay through the firewall is only 10 gauge.  If you've got your lights, wipers, HVAC, and rear defroster all going at the same time, that's a substantial draw off that one wire.  It might not hurt to run a separate parallel feed in to power the accessories.  If you used the stock circuit for the battery half of the fuse box, power windows, etc. and ran another feed through a relay to the accessory half, you might be better off all the way around.

 

Not to go crazy with the relays, but your headlights will also benefit from replacing the stock harness with relays and a dedicated feed, and your starter might be happier if the solenoid feed wasn't routed through the NSS.

Edited November 8, 2016 by KongaMan (see edit history)

[1965rivgs]

4 hours ago, KongaMan said:

 

IMHO, both the ignition and light switches are weak points.  Each could benefit from moving some of its functionality to relays.  If -- as you experience -- the switch is getting hot, that's energy being lost. It's also not doing your switch any favors to have it heat up that much.

 

Have you ever measured the voltage at, say, the blower when it's running on high?  It would be interesting to see how much it's dropped from the battery.

 

It seems that bypassing the ignition switch by rerouting the ACC circuit through a standard Bosch 50A relay should be pretty easy:

- Cut the pink wire between the switch and fuse box*.

- Connect the end from the switch to terminal 86.

- Ground terminal 85.

- Connect a battery feed to terminal 30/51.

- Connect the pink wire to the fuse box to terminal 87.

 

* You might not have to cut it; it might connect to the box with a spade lug, so you can just unplug it.

 

One can probably assume that the individual circuits (save the cigar lighters) are adequately wired, so making the feed to the fuse box more robust should be enough.  However, the battery feed from the horn relay through the firewall is only 10 gauge.  If you've got your lights, wipers, HVAC, and rear defroster all going at the same time, that's a substantial draw off that one wire.  It might not hurt to run a separate parallel feed in to power the accessories.  If you used the stock circuit for the battery half of the fuse box, power windows, etc. and ran another feed through a relay to the accessory half, you might be better off all the way around.

 

Not to go crazy with the relays, but your headlights will also benefit from replacing the stock harness with relays and a dedicated feed, and your starter might be happier if the solenoid feed wasn't routed through the NSS.

This is called an "ignition relay" in later model cars and trucks. A good idea to take the load from the ignition switch but represents yet another "switch" in the circuit which has the potential to fail....and they typically do, very common failure.

The battery feed for the horns is at the battery cable junction where the relay is located. The horn related wire feed into the cabin is the ground circuit for the coil in the horn relay and is the low current side of the relay.

  Tom

[Scott Mckenzie]

So , Do I slide a spade connector into the end of the fuse of choice ? There does not appear to be any extra  spots available on the fuse block according to the manual. 

 

[KongaMan]

1 hour ago, Scott Mckenzie said:

So , Do I slide a spade connector into the end of the fuse of choice ? There does not appear to be any extra  spots available on the fuse block according to the manual. 

 

 

You can't connect directly to the fuse.  There are several ways to do it:

- You may be able to shove a connector (or the bare end of the wire) between the side of the fuse clip and the box or between the end of the fuse and the box.  That's a kind of cheesy way to do it, but it might work.

- Identify the circuit you want to use, then open up the harness and use a tapping connector (see picture below) to splice in the lead from the fuel pump. You can get these at Home Depot, Radio Shack, etc.

- Get an AGC fuse tap (see picture below).  There's an active eBay auction as we speak; 10 for $6.

 

Edited November 8, 2016 by KongaMan (see edit history)

[Scott Mckenzie]

4 hours ago, KongaMan said:

 

You can't connect directly to the fuse.  There are several ways to do it:

- You may be able to shove a connector (or the bare end of the wire) between the side of the fuse clip and the box or between the end of the fuse and the box.  That's a kind of cheesy way to do it, but it might work.

- Identify the circuit you want to use, then open up the harness and use a tapping connector (see picture below) to splice in the lead from the fuel pump. You can get these at Home Depot, Radio Shack, etc.

- Get an AGC fuse tap (see picture below).  There's an active eBay auction as we speak; 10 for $6.

 

The agc fuse tap is genius. I have used a tapping connector before ..I think to wire in an 8-track  ha ha