Best location to tap power for electric fuel pump on '59?

[Guest]

My jets for the carb came in today and I finally put it all back together and back on the engine. Filled the bowls with gas, and the engine purred like it was started yesterday (not 11 years ago). The catch was that the electric fuel pump was hooked up to a 110 to 12 volt inverter, not to the car battery. I ran the car this way for about 45 minutes to check the coolant, and test the carb. Everything worked great.

I then hooked the positive wire on the fuel pump to the positive terminal on the coil and the negative to a hose bracket on the body. The fuel pump feels much weaker and eventually stops pumping, killing the engine.

Where is the best place to give power to the fuel pump? I've read that the ballast resistor works, but that it also gets hot. I really dread car electronics and barely know anything about them, so any insight would be a big help.

Once again, thanks for everyone helping with this project. I'm thinking if I can get this fuel pump situation ironed out, I'll take it for a short test drive over the weekend.

[simplyconnected]

...the electric fuel pump was hooked up to a 110 to 12 volt inverter, not to the car battery. I ran the car this way for about 45 minutes to check the coolant, and test the carb. Everything worked great.

I then hooked the positive wire on the fuel pump to the positive terminal on the coil and the negative to a hose bracket on the body. The fuel pump feels much weaker and eventually stops pumping, killing the engine...

Oh boy... alright, ask yourself this question:
'What method does a modern car use to run the electric fuel pump?'
They take power off the battery, fuse it, control it with a relay and a Cutoff Switch, and a PAIR of wires feed the pump. That's right, they run a separate ground wire in the wire harness all the way to the fuel tank. A hot wire and a ground.

I strongly suggest you do the same, regardless of where you mount your fuel pump. The Cutoff Switch is a pendulum. If you get into a serious crash, the pendulum swings and opens the electrical connection. You have a white button in your trunk to reset this switch. It prevents the fuel pump from running in case of an accident where the engine is stopped (or upside down) but the key is still on.

NEVER power any accessory from your ignition coil. Drawing more power will either burn the ballast resistor open or you will rob precious amps from your coil and the motor will run like crap.

There aren't many functions more important than fuel delivery. Run a small wire (#16) from your key switch (ignition post) to the coil of a separate relay. The relay may be mounted in the engine compartment. The other relay coil wire connects to ground. Then connect a power wire from your battery, through a small fuse (5 to 10-amp) and on to your relay contact. The other side of the normally open contact goes to the Cutoff switch and on to the fuel pump. NEG ground should start at your battery and run straight to the fuel pump. This method elliminates poor body grounds from affecting your new pump.

I hope this helps. If you have questions or concerns, let's talk about them. - Dave

[Guest]

There aren't many functions more important than fuel delivery. Run a small wire (#16) from your key switch (ignition post) to the coil of a separate relay. The relay may be mounted in the engine compartment. The other relay coil wire connects to ground. Then connect a power wire from your battery, through a small fuse (5 to 10-amp) and on to your relay contact. The other side of the normally open contact goes to the Cutoff switch and on to the fuel pump. NEG ground should start at your battery and run straight to the fuel pump. This method elliminates poor body grounds from affecting your new pump.

Dave, thanks for the info. As far as the relay goes, can I use a generic autozone 5-prong relay? What type of cut off switch to use? This definitely sounds like the safest route in hooking up an electric fuel pump.

[simplyconnected]

Yes, a simple generic relay will do just fine. Nothing fancy is required, here. You only need one set of normally open contacts.

Every car produced with an electric fuel pump (for the past number of decades) has a Fuel Cutoff Safety Switch. Bone yards crush them on a daily basis. Brand doesn't matter either, because the auto manufacturers buy these switches. This is one of those safety items that is rarely ever used (like air bags) but very important if you ever get into a crash. Most folks pay zero attention to the one in their car but every owner's manual details their function, location, and how to reset them by pushing the white button. - Dave

[ThunderBaker]

Electric fuel pump addition

Amphiduck, Summit Racing sells a good kit for installing an electric fuel pump.It comes with a relay,relay base,fuse ,wire,and a good wiring diagram.
Marshall

[simplyconnected]

I looked at some of the systems offered, and I have to take issue with them. They say the ICC mandates that the fuel pump cannot run without the engine turning.

On every modern car I've seen, as soon as the key is turned to 'run', I can hear the electric fuel pump inside the gas tank rev up to pressurize fuel to the injectors. Carbureted engines also need the fuel bowl filled before they start, so I don't see any difference in operating procedure.

Some aftermarket systems use a Oil Pressure Switch to energize a relay (which then enables an electric fuel pump). That's putting the cart before the horse. Why not simply offer a fuel Inertia Switch like all the OEM cars use? I see them on eBay for ten bucks, but bone yards crush them every day. All Inertia Switches cut electrical power the same exact way regardless of brand. Bone yards usually snip the connector with the switch and sell the whole thing. - Dave

[KULTULZ]

I looked at some of the systems offered, and I have to take issue with them. They say the ICC mandates that the fuel pump cannot run without the engine turning.

On every modern car I've seen, as soon as the key is turned to 'run', I can hear the electric fuel pump inside the gas tank rev up to pressurize fuel to the injectors. Carbureted engines also need the fuel bowl filled before they start, so I don't see any difference in operating procedure.

Some aftermarket systems use a Oil Pressure Switch to energize a relay (which then enables an electric fuel pump). That's putting the cart before the horse. Why not simply offer a fuel Inertia Switch like all the OEM cars use? I see them on eBay for ten bucks, but bone yards crush them every day. All Inertia Switches cut electrical power the same exact way regardless of brand. Bone yards usually snip the connector with the switch and sell the whole thing.

- Dave

You want the engine on a safety switch (pre-EFI engine oil pressure cutout) to stop the pump in case of an engine failure or a collision that may not set the inertia switch.

EFI energizes the pump to prime but if the ECM does not see a PIP signal after a few seconds will cut the pump power supply.

Personally (and your mileage may vary), I would wire the pump (via relay) to energize with the IGN SW turned to the ON position (to prime the system) and it will still be powered on the START position for cranking. The oil pressure cut-off will then de-energize the pump if a no start condition is encountered.

You will need (IMO) both an inertia switch and a cut-out switch on a properly fused circuit.

Did that make any sense?

[simplyconnected]

I guess there are many 'custom' ways to skin this cat. I'm in favor of 'safety' because I've seen the result when there was none. Will everyone meet with catastrophic failure? Certainly not, but just in case Murphy shows up, an ounce of prevention goes a very long way.

Back in my hot rod days, we never thought twice about connecting electric fuel pumps with NO safeguards. Now, I consider that, 'shakin' dice'. 'Simplicity' plays a role too because the more complicated things are, the more parts that can fail. That's why I always ask the question, 'what do modern cars use?' Teams of Product Engineers must sign-off before the first model is built, and we have a long history to reference.

I'm not opposed to using the Oil Pressure Sw., but for cars that lose their fuel prime, it's back to the same old, cranking forever, before gas gets to the carb. The beauty of an electric pump is that it delivers fuel before the engine cranks. If the pump is mounted close to the tank, the posibility of vapor lock is history. And again, OEMs haven't used mechanical pumps for decades and they never looked back. So, I like a simple Inertia Sw., in series with a fuse, fed by the Key Sw.

Using relays helps a lot to lighten the load on dashboard switches. I'm in favor of a separate Headlight Relay and a separate Electric Fuel Pump Relay, for a host of reasons. I always use relays for trailer lights, to preserve steering column turn signal and stop light wiring. At two bucks each, why not use relays! - Dave

[deany41]

Still unclear on wiring electric fuel pump

I guess there are many 'custom' ways to skin this cat. I'm in favor of 'safety' because I've seen the result when there was none. Will everyone meet with catastrophic failure? Certainly not, but just in case Murphy shows up, an ounce of prevention goes a very long way.

Back in my hot rod days, we never thought twice about connecting electric fuel pumps with NO safeguards. Now, I consider that, 'shakin' dice'. 'Simplicity' plays a role too because the more complicated things are, the more parts that can fail. That's why I always ask the question, 'what do modern cars use?' Teams of Product Engineers must sign-off before the first model is built, and we have a long history to reference.

I'm not opposed to using the Oil Pressure Sw., but for cars that lose their fuel prime, it's back to the same old, cranking forever, before gas gets to the carb. The beauty of an electric pump is that it delivers fuel before the engine cranks. If the pump is mounted close to the tank, the posibility of vapor lock is history. And again, OEMs haven't used mechanical pumps for decades and they never looked back. So, I like a simple Inertia Sw., in series with a fuse, fed by the Key Sw.

Using relays helps a lot to lighten the load on dashboard switches. I'm in favor of a separate Headlight Relay and a separate Electric Fuel Pump Relay, for a host of reasons. I always use relays for trailer lights, to preserve steering column turn signal and stop light wiring. At two bucks each, why not use relays! - Dave

I purchased and installed a Posi-Flo electric fuel pump to the frame by the fuel tank yesterday that was purchased at NAPA. I wired per their instructions which was from the positive side of the starter relay with a fused line to the pump. They recommend the Oil Pressure switch which I regrettfully have on order since the object was to prime the fuel bowls prior to starting engine. I am confused on wiring since I am a novice in that (an many other areas). Do I understand your wiring correctly Dave? Key switch to separate relay to inertia switch to fuel pump. Anything wrong with the inertia switch being in the engine compartment? Thanks!

[simplyconnected]

Dean, you can mount the Inertia Switch anywhere you want. Auto companies mount them in the trunk area as a 'convention' because resetting them is convenient, they are protected from the elements, the electrical connections are close to the fuel pump, and the trunk area is usually not vulnerable to collission.

A long as you remember where to reset the switch, you can mount it anywhere you like. Simply put, all electrical devices are wired in a big series but in two circuits. The power circuit starts at the battery side of your Starter Switch, it feeds a Fuse, normally open Relay contact, and ends at the Fuel Pump. The control circuit starts at the IGN side of your Key Switch, goes through the Inertia Switch and ends at the Relay coil, so the fuel shuts off with the key.

If you need a diagram, I will draw one for you. Actually, I have an electrical diagram in a 1990 Ford Mustang Manual. That is how they wired Ford cars. - Dave

[KULTULZ]

Hey Dave,

In addition to both the cut-out switch and inertia switch, what do you think about wiring in a spring loaded toggle switch that can only be activated from the RUN position to prime the system and then when it is primed (pump shutoff) and when the key is turned to START that circuit is then by-passed?

This will hopefully negate cold cranking (building oil pressure) while waiting for the fuel system to be primed.

Old T-950 trucks (gasoline) had a carburetor and electric pump. I will try and find if they had a safety circuit incorporated into theirs.

[simplyconnected]

Gary, I was looking at my 1990 Ford Mustang EVTSM (Electrical & Vacuum Trouble-Shooting Manual) to post the wiring diagram. It's very simple. Turn the key on and the pump works through a relay which is controled by an Inertia Sw. As soon as the key is on, the pump starts. Nothing fancy or complicated. If the car gets in a crash, the Inertia switch opens and the gas shuts off. Really, that's what we want.

Oil pressure, time delay or momentary switches were not used by Ford because they aren't necessary. Some guys let their car sit for months so they use electric fuel pumps just to supply gas for startup, then they let the mechanical pump take over. There are many ways to do this so I simply follow the OEM method. - Dave

[KULTULZ]

Gary, I was looking at my 1990 Ford Mustang EVTSM (Electrical & Vacuum Trouble-Shooting Manual) to post the wiring diagram. It's very simple. Turn the key on and the pump works through a relay which is controled by an Inertia Sw. As soon as the key is on, the pump starts. Nothing fancy or complicated. If the car gets in a crash, the Inertia switch opens and the gas shuts off. Really, that's what we want.

Oil pressure, time delay or momentary switches were not used by Ford because they aren't necessary. Some guys let their car sit for months so they use electric fuel pumps just to supply gas for startup, then they let the mechanical pump take over. There are many ways to do this so I simply follow the OEM method.

- Dave

Dave, with EEC-IV, when the car is started, the pump is initiated with the IGN (relays). If the ECM does not see a PIP signal within a set amount of time, the fuel pump circuit is opened. This is a safety say if there was a mechanical problem. The inertia switch trips and opens when a certain impact level trips it.

There is a delay feature built into the system.

What I am getting at is if the engine fails or shuts off, there should be a safety circuit to cut the fuel off automatically free from the IGN SW.

I'll let it go.

[deany41]

Electric Fuel Pump-inertia switch question

Gary, I was looking at my 1990 Ford Mustang EVTSM (Electrical & Vacuum Trouble-Shooting Manual) to post the wiring diagram. It's very simple. Turn the key on and the pump works through a relay which is controled by an Inertia Sw. As soon as the key is on, the pump starts. Nothing fancy or complicated. If the car gets in a crash, the Inertia switch opens and the gas shuts off. Really, that's what we want.

Oil pressure, time delay or momentary switches were not used by Ford because they aren't necessary. Some guys let their car sit for months so they use electric fuel pumps just to supply gas for startup, then they let the mechanical pump take over. There are many ways to do this so I simply follow the OEM method. - Dave

Appreciate the insights. Found a wiring diagram online for the Mustang....it had wiring symbols galore so I will give it a go with the wording you illustrated in your initial reply which includes the Key Switch-inertia switch-relay.
Your quite right about the storing for months- mid Oct to May at this elevation. I found it interesting that the see thru fuel filter was about a third full with engine running with the elect. pump as opposed to a slight stream running though it with the mechanical pump. I will assume it is OK to leave the mechanical pump on. Thanks Dave and Gary.
As a side note...this forum is great and well laid out. I have been going through each post and gleaning much information. Hopefully I will find posts that address my fuzzy black spark plugs.

[KULTULZ]

Hopefully I will find posts that address my fuzzy black spark plugs.

If I doo'd it I will get a spankin'... I DOO'D IT!

Are they fuzzy black on the outside or on the tip?