more electric fuel pump ?s

[kmcormick9]

One step closer to having those SUs in..

i have hit a problem...... all you guys with aftermarketn electric fuel pumps must have some way to trigger them.... how do you do that? i am considering putting a toggle switch in the radio console, but if theres a more original way.. i want to know. help me out guys.

 

[kmcormick9]

let me explain myself a little better for you guys unfamiliar with midgets: my car came originally equipped with the cam driven mech fuel pump. i have a solid state electric replacement i am putting in. i would like to have it start automatically with the ignition. are there any start wires left over from the old days of su electrics?

 

[Bret]

I’m not a Midget guy. But assuming that there isn’t existing accommodations for an electronic fuel pump – I can’t imagine this would be any different than hooking up a stereo or any other after market electronics device. You should be able to wire up you fuel pump by connecting it to just about any circuit that is live when you have your ignition on.

Good Luck,

Bret

 

[kmcormick9]

what circuits are ignition on? i would rather not mess with my actual ignition wiring, but other than that i cannot think of any thing that starts when i start the car

 

[Bret]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by kmcormick9:
what circuits are ignition on? i would rather not mess with my actual ignition wiring, but other than that i cannot think of any thing that starts when i start the car<hr></blockquote>

Like I said – I’m not a Midget guy. But if they are remotely similar to the wiring in MGBs, then you should be able to make a connections in several locations without affecting anything.

I recommend that you first get a schematic for your model year car and look it over before you start the installation. A good schematic diagram should be available in just about any shop manual. Once you have that in hand – I’m sure that you’ll find that there are plenty of locations to safely make your connections. The master or main fuse block would seem to be your best bet.

As an example my 78 MGB has it’s fuse block located in the engine compartment on the passenger side firewall right next to the coil. A simple test to find a safe place to make your connection – would be to use a voltmeter find out what fuses/connectors are hot (+12V) and what are cold (0V) when you turn on & off your ignition key switch.

Likewise you might want to consider providing the fuel pump with it’s own dedicated fuse for extra protection.

Bret

 

[StevenA]

I do have a 76 Midget and I did have an electric fuel pump connected thru the fuse block. There are a couple of things that I feel obligated to say...1. The answer given above is a good one, and your skematics in a Chilton or other aftermarket book are adequate to find a location to hook up a fuel pump (be sure the circuit can handle the amps that are being added along with whatever is on the circuit currently and do not just put in a higher amp fuse...the wiring will melt) and Victoria British has listed several books on MG/British Leyland wiring...BUY IT TOO, and 2. Be or become very knowledgable about wiring and electrical circuitry.. you own a Lucas product and I for one have been thru many headaches and spent numerous hours finding "gremlins" in the wires. MG/MG Midget/Triumph/Austin Healey/ etc are all linked by one common thing... Fragile and sensitive wiring.

However, I do not call it "bad" or poorly designed like I have heard from American Mechanics; but simply fragile, delicate, sensitive, touchy, and sometimes frustrating. Get some books, read, read, and then do ( like Bob Villa... measure twice and cut once). You really should have a relatively simple time adding an electric fuel pump...not a major project at all.

 

[StevenA]

PS... Your question was "how to trigger them"... do you mean how to turn them on ? If they are added into the ignition switch circuitry then they will "fire up" or start working when the key is turned to the on position. If you want to use them as part of a theft preventative measure... THEN you could use a toggle switch hidden or placed in a less than obvious location and if your car was "hot wired" it would run only about one half block before it ran out of gas. Two of my cars are wired that way... I might do the same for others ...but MGs have an impact sensitive switch that I use to turn off the fuel. Probably not the best thing to do...since most MGB owners know what and where it is. But then I don't think true Britishers are ever car theives... we all work too hard to get them right and are proud of doing it ourselves.
Good luck

 

[StevenA]

PS2... I should mention, just in case, that one should never cut wiring and splice into the wire by adding another wire. Cutting and splicing electrical wire (home or car) will create/cause resistance and resistance will overload a circuit or melt wires (due to heat caused by resistance). Many people do not know this even if they are very wise mechanically. Use a tandem conector or splitter and don't just cut into the circuit or wire.
I apologize if you already know all of this; but don't want to let a fellow forum member make mistakes that I myself could make.

 

[Bret]

Wow! StevenA made some great suggestions. Wish that I’d had thought to point’em out myself. Can’t say enough about the dangers of splicing wires. But I particularly liked the suggestion of making sure to check the current rating (amps) of any fuses you might use.

That said I thought I might add to his suggestion. I would look for the main voltage into the fuse block and tap off of that with a dedicated fuse for the fuel pump.

The main reason for this is that the existing fuse has a particular current rating for the circuitry it protects. Example: A 10 Amp fuse might see a nominal current flow of 3 to 4 amps, during normal operations. So should any new load (say the SU fuel pump) be added to that fused circuit – the chances of coming close to or exceeding (blowing) that fuses rating is drastically increased. And as Steven so wisely pointed out – the answer is “NOT” to replace the existing fuse with a higher rated fuse.

It is for that reason that I recommended the dedicated fuse for the electronic fuel pump circuit. What I would do – is try to locate and connect the new circuit into the main power going into the fuse block.

Also if the component isn’t supplied with the recommended fuse. Try to determine the required current needed to drive your new fuel pump and use the 1/3’rd rule. In other words – should your new fuel pump require 0.333 (1/3) amps of continuous current – a 1 amp fuse will suffice. I would also recommend that you use a “slow blow” fuse to compensate for transient spikes.

Bret