• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Fuel pump cut off switch

Share this page

jmwuva05

jmwuva05

Senior Member
Country flag
Offline
I am considering switching to an electric fuel pump on my BE (tired of vapour lock in this heat). Has anyone else who has installed an electric fuel pump used a pump kill switch? If so which type oil pressure or inertia? I was thinking of the inertia one moss and VB sell, maybe mounting it behind the dash or to the inner side structure panel in the boot. Also which type of pump would be best SU or facet?
 
I have a Facet electric fuel pump, and as much as I'd like to install a safety switch, I do wonder if either of these options will really do the job.

The pressure switches I've seen all seem to be set to turn on around 5-10 psi. The BE oil pressure can drop close to this level on hot days, at idle, and I'm concerned that the switch might shut off the engine under those conditions. Another concern--suppose the car sits for a while and the fuel level in the float bowl drops. How do you start the car? Until it's running, the fuel pump won't operate, but you need to have it running to refill the carbs. Maybe cranking will raise the pressure enough to turn the switch on, but even then you'll need to crank it a lot.

As for the inertial switch--there are a lot of variables that the manufacturer doesn't tell you about. How much inertia does it require, and from what direction? Would it work for a side or rear impact or just front? Will hitting a pothole trip it?

My solution, when I get a chance to do it, will be an electronic circuit that senses when the engine is running, from the ignition coil voltage, and turns the pump on. It will have an override so that the pump is turned on for, say, 20 seconds as soon as the ignition switch is turned on.
 
The Megasquirt guys like the inertia switches that can be found in the trunks of late 80s through early 90s Fords.

An inertia switch is high on my to do list. Oh my that list is long!
 
I was thinking about using the SU solid state pump but I cant seem to find a mounting bracket listed in any of the major suppliers catalogs. Anyone know where one of these can be found?
 
It's a simple band iron bracket you can make out of a 1/2" wide piece of steel from any hardware store.
Mount it on a couple of rubber grommets to keep the noise down. On a Bugeye you will have to add mounting points anyway so the bracket doesn't much matter as long as it fits around the pump.
For a shut off switch, if you want the dash to remain stock, I have used the dash lamp switch since I keep the dash lamps on all the time anyway.
This is not an inertia switch but being able to kill the fuel pump with a switch is a great theft device.
 
I never did get around to installing a safety switch on my Opel GT's electric fuel pump. Then the accident. I had mine run through a rocker on the dash though. One of the first things I did after the wreck was hit that switch, although the battery took a direct hit and that killed all electrics immediately anyway. Can't always count on yourself though, may not be conscious enough to turn it off. Gas getting dumped onto a hot wreck isn't a nice thing.
 
I picked up an old inertia switch from an Alfa Romeo that works great. If it's placed close to the driver, the few occasions where it could trip from hitting a severe pothole, would be easily reset while still driving.

An oil pressure switch would work well but bypass it with a starter wire with a diode. (on the BE this is the starter cable after the high power starter switch)
 
Back
Top