Electric fuel pump safety

miniceptor86

miniceptor86

Senior Member
I’m going to install an electric fuel pump to aid in starting after dormant periods. The installation instructions show using an positive oil pressure switch to prevent the fuel pump from continuing to run in case of an accident. I understand but how long will I have to crank do generate enough oil pressure to close the switch? That may negate the reason I’m installing the pump. Should I just switch the pump at the dash and use it to build pressure before starting or are there other ways like hooking it to the start button?
 
I have an oil pressure switch on mine and it works fine.
Starts right up.
The switch doesn’t stop the engine from starting because you will have fuel in the bowl..
Say you were in a wreck….the engine stops running, oil pressure drops and pump shuts off with key still on.
Another option is an inertia switch. Most new cars have them in order to shut off elec. fuel pumps in the event of a crash. Find them on Amazon or many other places.
 
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The other thing to consider is a momentary switch (think push-button). It does not take long for an electric pump to fill the fuel bowl and you can usually hear when the pump slows down due to the float closing off the inlet.

On race cars we always install a "roll-over" switch that kills the ignition in case we have an issue . . . same reason.
 
I use a 2 position toggle switch that is sprung so it has to be held when priming. I mounted it in an existing hole at the bottom of the dash so it can't really be seen.

GB
 
If you get the right type of oil pressure switch (N/O or N/C) it will let the pump run until it gets oil psi, then will stop power to the fuel pump and then the mechanical pump will keep it running,, can't remember which type switch it is Normally open/ Normally Closed
 
rickeagle said:
I have an oil pressure switch on mine and it works fine.
Starts right up.
The switch doesn’t stop the engine from starting because you will have fuel in the bowl..
Say you were in a wreck….the engine stops running, oil pressure drops and pump shuts off with key still on.
Another option is an inertia switch. Most new cars have them in order to shut off elec. fuel pumps in the event of a crash. Find them on Amazon or many other places.
Click to expand...

I think lack of fuel in the carb bowl is why it cranks so long after sitting a week or more.
 
1800wingrider said:
If you get the right type of oil pressure switch (N/O or N/C) it will let the pump run until it gets oil psi, then will stop power to the fuel pump and then the mechanical pump will keep it running,, can't remember which type switch it is Normally open/ Normally Closed
Click to expand...

It would be normally closed
 
You can get a three position switch......on-off-momentary on..... with some type of emergency shut off in the -on-position......Mark
 
if only for starting and then the mechanical pump takes over a simple push button will work well but if its going to run fulltime then a tachometric relay could be the answer they are used on propane vehicles and when ignition is turned on power up for a short burst to prime the system and when they detect a ignition pulse come on line full time until the ignition pulse stops [eng stalled] then they shut off personally only way i will install an electric pump last thing you need is to have a bender and keep pumping fuel
 
aussie merc said:
if only for starting and then the mechanical pump takes over a simple push button will work well but if its going to run fulltime then a tachometric relay could be the answer they are used on propane vehicles and when ignition is turned on power up for a short burst to prime the system and when they detect a ignition pulse come on line full time until the ignition pulse stops [eng stalled] then they shut off personally only way i will install an electric pump last thing you need is to have a bender and keep pumping fuel
Click to expand...
I have a Ford impact switch installed that cuts the elec. to the pump in the event of a "bender" as you call it.
 
I have a oil pressure switch on one of my cars and the previous owner put a toggle switch to bypass the oil pressure switch when starting cold. If you forget to change the toggle switch it will die when it gets the oil pressure up. Don't have to use that toggle the rest of the day of driving.
 
51 MERC-CT said:
I have a Ford impact switch installed that cuts the elec. to the pump in the event of a "bender" as you call it.
Click to expand...
Me too, on the flatrod which runs on the electric pump full time. Pulled an inertia switch out of a junkyard nineties Ford Taurus, easily found behind the trunk side panel.

But if only using the elec pump for priming, then seems to me a momentary contact switch on the dash is all you need. As original poster said above, keep it simple.
 
Here's how I hooked up my electric fuel pump oil safety switch. The car uses only an electric fuel pump with an ON/OFF toggle switch under the dash. There is no mechanical pump. When you get in the car and flip the
ignition switch lever to ON and also flip the fuel pump toggle switch to ON the electric fuel pump "pumps" gas to the carb. You can then start the car and flip the fuel pump toggle switch to OFF and the fuel pump will still feed gas to the carb as needed.

In case of an accident where the engine stops running the oil pressure drops and automatically shuts OFF the pump.
The sketched drawing you see was made when the setup was configured as shown in the last two photos. The current set up is shown in the 2nd photo. The same wiring set up to the fuel pump pressure switch applies in both scenarios. The engine is an 8BA.
 

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I have a Standard Motor Products PS-64 Oil Pressure Switch
When you are cranking the electric fuel pump is powered regardless of the oil pressure. Once the engine is started the electric pump is powered UNLESS the oil pressure drops below 8psi I believe. I also have an inline toggle switch wired like 19Fordy describes above.
This is the wiring diagram.

495972
 
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