MG MGB and MGB GT Tech Talk
Being the safety fast kinda guy I am I wanted to install a fuel cutoff rollover switch on my fuel pump.
Being the cheap s.o.b. kinda guy I am I don't want to spend $50 on it.
I'm thinking a simple mercury switch installed in the fuel power line in the engine compartment would work just as well.
Any thoughts or has anyone tried this?
Thanks
Mont
I would think a mercury switch would be too sensitive and may switch your fuel pump off when you hit bumps and don't want it turned off. It's a safety feature and I would not trust something other than a switch designed for fuel shut off.
That said, I have used fuel pump inertia switches from a Ford wired into the fuel pump circuit of the MG's I have owned. The ones I found were in Fords from the 90's, one came from a Tempo, they were located in the trunk. The switch was even made in the UK. If you see Fieldbuilder his car should have one unless he removed it, it's just behind the fuse box. I think I paid $5 each for the two I purchased.
Clifton
find a salvage MG of late years and take the one off the firewall on the inside driver's side.
X2 on what Gordon said.
On the Fords, the switch goes back to at least the mid 80's. I have one in my '85 Marquis and its the same in my "91. Not sure about my '97 cause I never paid attention. I paid $5 and change at a salvage yard to replace the one I smashed with 2X4's (oops) about 5 years or so ago. Should work in a roll over assuming you were hit to cause the rollover or there is enough "G" forces during the roll-over itself to trigger the inertia switch.
If you want to go with the mercury switch, I'd find one that has one of the internal terminals shaped like a "U". These can be tilted a little more than the one in your pic. This will help against cut-off from vibration. BUT, it will not shut off if you are hit AND don't roll over.
Monte,
I think it will work but mercury is an extreme poison when set free!
On 1975 on B's, ther was an inherta switch behind the dash that also was designed to switch off the fuel pump in case of a collision. Other cars also had this type of swiches built in, Ford Mondeo and Rover K-Series engined cars with EFI.
When wiring a cut of swich shout also a fuse and a relay should be considered in this cuircit.
On my GTV8 I have installed one of this switches from a Ford behind the whiper reservoir on the bulkhead.
Ralph
Monte, it's still on Red. Let me know when to come over.
Clifton, I haven't messed with any of the fine work you did to Red.
I'm just driving the heck out of it !!!!!!!!!!
Adding my voice to those who reject the mercury switch. I also believe it will be problematic when it is supposed to be connected, and unreliable in disconnecting in a collision. As long as the sensor is upright, it will keep conducting (even though the car has rolled over three times!)
$50 is a lot for a switch - but I imagine that much of that cost is in making the switches foolproof, or as close to foolproof as they can be. They probably have a lot of insurance to handle litigation too! :)
I've used an inertia fuel cutoff from a Ford Escort. Has a nifty red button for reset in case you take a speed-bump too fast (which hasn't happened yet), cheap from the junkyard. I also hooked up the lead that went to the dashboard light to a little piezo buzzer to let me know in case the thing ever trips.
The one in my old Crown Vic popped with I spun her into a guard rail at highway speeds. Popped the trunk, pushed the button, and drove it off the road.
