The Ford Barn

Bored&Stroked · 02-24-2016, 04:53 AM

The term 'inertia' switch is the correct one - don't know why I used "roll-over". We also used a Fox Mustang switch (was cheap and easy). Essentially there is some sort of weighed "ball" or other mechanism inside the switch. An impact or roll-over condition will jar the ball loose and cut the power to the pump (or any other system that you have on a relay). I'm just happy to say that Pete (up above) hauled some Ass in the car at Bonneville and DIDN'T jar it loose . . . though he gave it a good try!

JSeery · 02-24-2016, 09:27 AM

If anyone doesn't know what they look like and is interested. I also posted a pressure switch photo. Almost all modern cars have them, these are just the ones I am familiar with and have used, very common and easy to get.

30-9 · 02-24-2016, 09:41 AM

Curious how are they connected and where are they connected?

sidevalve8ba · 02-24-2016, 09:43 AM

I prefer the inertia switch over the oil pressure switch for one simple reason. On a cold start I like to flip on the fuel pump switch to build fuel pressure and fill the carburetor float bowls before I pull on the choke or hit the starter button. My engine starts a lot quicker that way. Otherwise you have to crank over the engine long enough to build oil pressure before the pump comes on.

Mike51Merc · 02-24-2016, 10:13 AM

I had a friend who burned out a bunch of pumps in a short time period. Turns out he had installed the pumps on the frame rail under the driver seat. As previously said, these pumps like to push, not pull.

As far as lifting, I like the old Facet (now Purolater) pulse type pumps. They're used on small aircraft if that's any indicator of reliability. The downside is they make some noise but you can only really hear it until the engine starts.

JSeery · 02-24-2016, 10:15 AM

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Quote:

Originally Posted by sidevalve8ba

I prefer the inertia switch over the oil pressure switch for one simple reason. On a cold start I like to flip on the fuel pump switch to build fuel pressure and fill the carburetor float bowls before I pull on the choke or hit the starter button. My engine starts a lot quicker that way. Otherwise you have to crank over the engine long enough to build oil pressure before the pump comes on.

The switch does have a by-pass in start so no oil pressure required while turning over the starter. But, I like it wired up so I can manually operate the fuel pump when I want.

The Inertia Switch just wires up inline with the electric fuel pump, very simple. The pressure switch is a little more involved, but not difficult. Here are some 12v neg ground wire diagrams that use a relay (I like relays!). I will draw up some simple diagrams for anyone not interested in the more complicated ones.

BUBBAS IGNITION · 02-24-2016, 10:15 AM

Quote:

Originally Posted by JSeery

When your pulling on the fuel you are dropping the pressure on it. If you are raising the level at the same time, that drops the pressure even more. The stock pump also conducts heat into the fuel. I would guess that the pressure drop with the electric pump was about the same as the original, but it was transfering less heat into the fuel. Believe you said it was getting into the vapor lock range because you could detect a sound change in the pump. Vapor lock depends on many factors, the pressure the fuel is seeing (suction, elevation, etc), the actual fuel mixture (different at different times of year or source), engine compartment temp and how much is being transfered to the fuel pump, carb, fuel line, etc. Lots of factors.

A thought in regards to vapor lock????? Ever thought that vapor lock must have air in the system to occur???????? No air, no vapor....

Points to ponder......

JSeery · 02-24-2016, 10:36 AM

Quote:

Originally Posted by BUBBAS IGNITION

A thought in regards to vapor lock????? Ever thought that vapor lock must have air in the system to occur???????? No air, no vapor....

Points to ponder......

Well, interesting point, but I don't think so. Have to think on that one a bit Bubba! A water well will only "pull" water to a specific height (~33.9 feet) for the same reason and then you have to use a "pusher" pump (submergible) or a jet pump. But, can fuel vaporize if there is no space to vaporize into? Not sure how that situation can exist and still be lowering the pressure over the liquid. Now I will be thinking about this all day!

Any practical example of a fuel system where you can pull the fuel through the lines and not have any space for the fuel to vaporize into Bubba?

A bones · 02-24-2016, 11:31 AM

Try this, we don't speak of air but gas, as in gaseous.

Boiling

If a liquid is heated the particles are given more energy and move faster and faster expanding the liquid. The most energetic particles at the surface escape from the surface of the liquid as a vapour as it gets warmer. Liquids evaporate faster as they heat up and more particles have enough energy to break away. The particles need energy to overcome the attractions between them. As the liquid gets warmer more particles have sufficient energy to escape from the liquid. Eventually even particles in the middle of the liquid form bubbles of gas in the liquid. At this point the liquid is boiling and turning to gas. The particles in the gas are the same as they were in the liquid they just have more energy. At normal atmospheric pressure all materials have a specific temperature at which boiling occurs. This is called the "boiling point" or boiling temperature. As with the melting point the boiling point of materials vary widely e.g. nitrogen -210oC, alcohol 78oC, aluminium 459oC.
Any material with a boiling temperature below 20oC is likely to be a gas at room temperature. When liquids boil the particles must have sufficient energy to break away from the liquid and to diffuse through the surrounding air particles. As these particles cool down and lose energy they will condense and turn back to liquid. When steam is formed by water boiling at 100oC the particles quickly condense as the surrounding air temperature is likely to be much less that 100oC so the particles cool rapidly. In fact the "steam" coming out of a boiling kettle can only be seen because some of the gas particles have condensed to form small droplets of water.

That thar Google is amazing.

JSeery · 02-24-2016, 01:43 PM

Good as far as it goes, but pressure is also a factor. Normal "boiling points" are at sea level. As the pressure drops so does the boiling point. At a low enough pressure water will boil at room temperature. One of the big factors in all of this is surface tension on the liquid, it allows the molecules at the surface to break free easier. Bubbas question was (I think) does fuel vaporize as easily if there is not an air/fuel interface for the surface tension factor. I'm not sure, but also not sure it is possible to maintain that condition in an automotive fuel system. It's an interesting question (at least to me it is).

02-24-2016, 04:53 AM	#21
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,062	Re: Best Place for Electric Fuel Pump The term 'inertia' switch is the correct one - don't know why I used "roll-over". We also used a Fox Mustang switch (was cheap and easy). Essentially there is some sort of weighed "ball" or other mechanism inside the switch. An impact or roll-over condition will jar the ball loose and cut the power to the pump (or any other system that you have on a relay). I'm just happy to say that Pete (up above) hauled some Ass in the car at Bonneville and DIDN'T jar it loose . . . though he gave it a good try!

02-24-2016, 09:41 AM	#23
30-9 Senior Member Join Date: Aug 2014 Location: MA Posts: 888	Re: Best Place for Electric Fuel Pump Curious how are they connected and where are they connected? __________________ Thanks - 30-9 1939, 1940

02-24-2016, 09:43 AM	#24
sidevalve8ba Senior Member Join Date: May 2013 Location: Harrisonburg, VA Posts: 841	Re: Best Place for Electric Fuel Pump I prefer the inertia switch over the oil pressure switch for one simple reason. On a cold start I like to flip on the fuel pump switch to build fuel pressure and fill the carburetor float bowls before I pull on the choke or hit the starter button. My engine starts a lot quicker that way. Otherwise you have to crank over the engine long enough to build oil pressure before the pump comes on. Last edited by sidevalve8ba; 02-24-2016 at 11:43 AM.

02-24-2016, 10:13 AM	#25
Mike51Merc Senior Member Join Date: May 2010 Location: Northeast Pennsylvania Posts: 1,582	Re: Best Place for Electric Fuel Pump I had a friend who burned out a bunch of pumps in a short time period. Turns out he had installed the pumps on the frame rail under the driver seat. As previously said, these pumps like to push, not pull. As far as lifting, I like the old Facet (now Purolater) pulse type pumps. They're used on small aircraft if that's any indicator of reliability. The downside is they make some noise but you can only really hear it until the engine starts. Last edited by Mike51Merc; 02-24-2016 at 10:28 AM.

02-24-2016, 11:31 AM	#29
A bones Senior Member Join Date: May 2010 Location: CLAYTON DE Posts: 1,282	Re: Best Place for Electric Fuel Pump Try this, we don't speak of air but gas, as in gaseous. Boiling If a liquid is heated the particles are given more energy and move faster and faster expanding the liquid. The most energetic particles at the surface escape from the surface of the liquid as a vapour as it gets warmer. Liquids evaporate faster as they heat up and more particles have enough energy to break away. The particles need energy to overcome the attractions between them. As the liquid gets warmer more particles have sufficient energy to escape from the liquid. Eventually even particles in the middle of the liquid form bubbles of gas in the liquid. At this point the liquid is boiling and turning to gas. The particles in the gas are the same as they were in the liquid they just have more energy. At normal atmospheric pressure all materials have a specific temperature at which boiling occurs. This is called the "boiling point" or boiling temperature. As with the melting point the boiling point of materials vary widely e.g. nitrogen -210oC, alcohol 78oC, aluminium 459oC. Any material with a boiling temperature below 20oC is likely to be a gas at room temperature. When liquids boil the particles must have sufficient energy to break away from the liquid and to diffuse through the surrounding air particles. As these particles cool down and lose energy they will condense and turn back to liquid. When steam is formed by water boiling at 100oC the particles quickly condense as the surrounding air temperature is likely to be much less that 100oC so the particles cool rapidly. In fact the "steam" coming out of a boiling kettle can only be seen because some of the gas particles have condensed to form small droplets of water. That thar Google is amazing. __________________ Enjoy yer day. Tom Hate can't fix what it started.

02-24-2016, 01:43 PM	#30
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Best Place for Electric Fuel Pump Good as far as it goes, but pressure is also a factor. Normal "boiling points" are at sea level. As the pressure drops so does the boiling point. At a low enough pressure water will boil at room temperature. One of the big factors in all of this is surface tension on the liquid, it allows the molecules at the surface to break free easier. Bubbas question was (I think) does fuel vaporize as easily if there is not an air/fuel interface for the surface tension factor. I'm not sure, but also not sure it is possible to maintain that condition in an automotive fuel system. It's an interesting question (at least to me it is).