Fuel cut off if in accident

Tweety · Post by **Tweety** » Thu Aug 28, 2014 10:47 pm

Got a new electric fuel ump with fuel return on my new weber 38/38 to be hooked up soon. Worried about the pump continuing to flow fuel out of say a severed fuel line if in a crash.

Any ideas how this is to be tackled. Might have asked this question a long time ago.

Gannon · Post by **Gannon** » Fri Aug 29, 2014 7:13 am

On the rally car I have been working on it has a second oil pressure switch that has normally open contacts and this is in series with the fuel pump relay. Fuel pump will only run when the engine has oil pressure. There is a override button for starting.

L series subarus had a black box that took pulses from the ignition coil and turned the fuel pump on only when it was getting pulses

steptoe · Post by **steptoe** » Fri Aug 29, 2014 8:29 am

http://www.ebay.com.au/itm/Peel-LPG-Saf ... 338a1b5a3e

and that is a bloody good price - same as what I pay the manufacturer ! Use it to drive fuel pump relay Tony. Made in Mornington, Vic

Subydoug · Post by **Subydoug** » Fri Aug 29, 2014 8:51 am

If your feeling like doing it yourself Tweety something like this should work.

Just have to play with the resistor and cap values to get the desired duration of fuel pumping after the engine stops. I wouldnt try using it on points though.

Regards

Doug

Tweety · Post by **Tweety** » Fri Aug 29, 2014 4:46 pm

thanks guys, went the Steptoe route. has been ordered.
Doug- what are those curly bits and triangles?????

steptoe · Post by **steptoe** » Fri Aug 29, 2014 6:55 pm

tony torment!!

poprock1 · Post by **poprock1** » Fri Aug 29, 2014 7:19 pm

re safety wiring; why not wire in an inertia switch as in new cars. Have done this on my electric Daihatsu as a requirement to cut power to motor contactors. Simple in line installation.

Tweety · Post by **Tweety** » Fri Aug 29, 2014 7:24 pm

Steptoe, mate. Why do you need a relay. Why not just an in line fuse.?

Poprock1....more detail please.

poprock1 · Post by **poprock1** » Fri Aug 29, 2014 7:29 pm

Also , still chasing 84 KM3 Sherpa parts as in previous posts

poprock1 · Post by **poprock1** » Fri Aug 29, 2014 7:50 pm

poprock1 wrote:Also , still chasing 84 KM3 Sherpa parts as in previous posts

Check eBay for fuel safety cut off switch

poprock1 · Post by **poprock1** » Fri Aug 29, 2014 7:54 pm

as in murky pic, small knob is reset switch. 3 leads, power or earth in out, or power cutout. Mine breaks earth fron contactor.

Subydoug · Post by **Subydoug** » Fri Aug 29, 2014 7:58 pm

Sorry Tweety. Circuit is an inline diode, then a pull down resistor of some high value and a cap to ground of some random value depending on the resistor value, the output of which goes to the base of a transistor, which pulls in your fuel relay. The pulses from the disty charge up the capacitor thru the diode, but the capasitor cannot discharge back to the distributor because the diode blocks the current. So then the capasitor slowly discharges thru the resistor. As long as the cap stays charged between pulses from the disty it will hold the fuel relay on. It may need an inline resistor to the base of the tranny as well, depends on what parts are used and the current flow.

Regards

Doug

steptoe · Post by **steptoe** » Sat Aug 30, 2014 9:09 am

relay ....hmm, coz I don't really understand electrics and electronics ?? The Australian designed and manufactured CP30 actually uses a built in relay"specifically suited to high current loads eg multiple lock offs" unlike transistor switching of some alternate components for same job. You will be using a relay anyway for fuel pump ?

The CP30 is designed to be switching solenoids of LPG safety valves, no idea of their loading compared to your fuel pump. So until someone says it is OK, I suggested a relay. No idea until I look at slip that comes with it "Unit is capabl of supplying an output of up to 12amps" Dougy and tambox will know what that means

The componnts have a coating to protect from the elements, it is not a sealed in epoxy deal
They also do a CP30 Saleen with added plug for the Supercharged Mustang Saleen Cars in USA

Inertia switch ? What, on Tweety ? Not quite sure an inertia switch would be a good idea in case Tweets pops a mono, err duo, actually

Tweety · Post by **Tweety** » Sat Aug 30, 2014 10:33 am

Doug, it's all double dutch for me- electronics. In 1973 I started a radio electronics course in the RAAF - yeh 17yo and failed two months into the 12 month course. Ended up a librarian lol

Jonno- seems the unit is water resistant then and not waterproof. Ok, means I'll place it in a good spot inside the dummy tank. I'll chase down a good relay. Might email the manufacturer actually.

Thanks all for covering this topic.

steptoe · Post by **steptoe** » Sat Aug 30, 2014 11:48 am

you'd need to know the current draw Amps of the pump before they could answer one way or another if you asked Peel staff of same surname - good old fashioned family business

Yeah, installed heaps under bonnet and ne'er a worry.

Tweety · Post by **Tweety** » Sat Aug 30, 2014 4:54 pm

This is the fuel pump I purchased a few months back.

It doesnt show a manufacturer and isnt printed on it either (gotta be chinese lol). The Facet type pump is similar and they draw only 1 amp. 1.5-3.5psi

Tweety · Post by **Tweety** » Thu Sep 04, 2014 12:44 am

Received reply from David Peel in regards to a query whether I need to wire up a relay or not to th LPG safety switch.

"The internal relay is maximum load rated at 10amps, hence a 1 amp draw pump
will be ok for the CP30 to drive. I have attached a document in regards to wiring up an external relay if the load is higher than 10amps, for your reference."

As the pump in question draws only 1 amp there is no need for an external relay. problem solved.