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Discussion Starter #1
Its taken 10 years but last Saturday I’d finally had enough of cranking the old girl into life after a few winter weeks so have bought an electric fuel pump. I’ve gone for the Facet Silver Top (Red Top seems a bit ott for the spider and I couldn’t find a Matsuba one anywhere).

Anyway I think I’m going to take Steve’s advice and mount it in the engine bay as appose to underneath (controversial?) as it should be capable of pulling the fuel up, it will be protected from the elements and fitting and wiring up will be easier.

My question is the wiring as I’m fine with taking engine and gearboxes apart but do struggle with electrics! Am I right in thinking that I want it to start on the key so do I just need to connect the positive wire to the coil positive and earth it to the body through the mounting bracket? Or I have read about fitting a switch in the car so you can prime before turning it over, is this worth while?

Oh and the last silly question which I’m sure is a yes, do I need to remove and blank off the mechanical pump or can I leave it in place?

thanks
 

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I cant see why you should not take it off the ignition feed to the coil, but I would have that switch a relay rather than direct to the pump, the pump will draw quite a current I suspect and could interfere with the ignition, maybe. In any case add a fuse into the circuit between the supply and the pump. I'll be interested to hear how the electric pump works out, something I have thought of. I think leaving the mechanical pump in place is not a bad idea in case the electric pump fails, that said, with only a mechanical pump you had no back up!
 

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Discussion Starter #3
Thanks, yes a relay is probably a good idea.

Good point about a back up. If leaving the mechanical pump in place would I put the electric one before the mechanical or after it and before the filter?

Thinking a bit more, wouldn’t the mechanical interfere with the electrical and restrict the flow to its ‘pulse’?
 

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Simon, I'd blank the mech pump off (after taking off the old pump and actuator rod out. That's what I've always done with mine).
Blanking plate and gaskets avail from CA.
Here's an easy wiring diagram.:-
I'm no electrician but found it easy to follow !
I also put a non return valve in the line from the tank, and a pressure regulator between the pump and the carbs to keep pressure at around 3 psi.
Just about to do the same on the Spider.
 

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Discussion Starter #5
Thanks Steve,

You’re more of an electrician than me! I get the picture with the exception of he middle bit! I can see that’s a relay (which I’m not familiar with and will have to read up on) but it says to splice in a feed from the OEM fuel pump but the mechanical one doesn’t have this? And if I take the positive from the battery and not the coil won’t it be on all the time?

Plus with regard to the regulator to keep it at 3psi, is the Filter King not up to this and i’ll need to replace or add to this?

Thanks
 

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Hi Simon, you do go to the live side of the battery with a fuse as shown. The "feed from the OEM pump" is because this guy originally had an OEM electric pump on the car, so instead of that you use either the coil, or the spare terminal on the ign switch that is live when ignition on, (or any live feed when ign is on presumably), and that acts as the trigger for the relay to provide the power from the battery, ie the coil or other live , (whichever you decide to use), is only acting as a switch. Essential to use a relay IMO for the reasons mentioned above. With a feed from the battery, and the trigger from either the coil, or any live when the ign is on, the pump only runs when the ign is turned on.
I have my Ti Super wired exactly like this, did the GTA Rep the same, and am doing the Spider same later this week.
 

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Discussion Starter #7
Will this work?
932567
 

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Discussion Starter #8
Plus where is the best place in the engine bay, from memory I thought there’d be room on the off side
932568
but looking at it things are pretty tight.
 

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Simon, NO!! 85 needs to go to earth. Steve makes a good point about a non return valve, I never thought of that. And I do actually agree, get rid of the old pump, as I said earlier, the mechanical pump didnt have a back up so why would an electrical one need one?
 

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Discussion Starter #10
Thanks TD, I thought the negative on the coil was earthed but I’ll run a wire and earth it on the body, back to the earthed pump mount?

I fitted a NRV a while a ago which didn’t help with the mechanical set up but I’ll reposition it now.
 

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Simon, Top Down is correct, you need to follow the diagram I posted. You could retain the expansion tank, and mount it on the chassis leg next to the fuel pressure regulator ((To answer your earlier question, the Malpassi is ideal for keeping the pressure to 2.5 - 3.5psi). However, there was never an expansion tank on the earlier cars (like my Giulia saloon), and I'm removing it on the Spider and just putting a drain from the radiator filler neck to the floor a la older cars, so the pump will go on the inner wing where the expansion tank used to be. Malpassi is next to it, nearer the front of the car.
See pic of the Ti saloon engine bay with the Mitsuba.
IMG_7293.JPG
 

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Discussion Starter #13
Thanks, deleting the expansion tank will certainly make things easier.

I think we’re finally getting somewhere!

How’s the Spider coming on by the way, will it be ready for Spring Alfa Day?
 

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Hi Simon, Spider coming on nicely. Replaced the heater valve today, I remember it being a real cow of a job from one I did before, but for some reason this one went easier, only took an hour and a half.. No leaks now and heater works perfectly.
That's almost all of the mech work done, all that's left are door cards and some minor bodywork, which may or may not be done by mid April, but as the Yorkshire Wildlife Parl is about half a mile away as thge crow flies,(lions very vocal tonight), I'll be there in one of them !
 

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Put the spare Mitsuba pump onto the Spider yesterday, again using the diagram I posted above. Also put a non-return valve in the fuel line, about a foot tank-wards from the pump, on the chassis leg, to stop drain back.
Works a treat
20200220_101405.jpg
20200220_101345.jpg
 

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I've been thinking about this for ages,especially in the winter!
A suck pump in engine bay is my preferred plan, using it only as a priming pump and retaining the mechanical one. So, a push switch to turn it on to prime carbs then turn it off. I've added a quick drawing of what I'm thinking of.
A permanent electric pump would surely need some sort of automatic isolator in case of a mishap to prevent fuel being pumped?
933921
 

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I would fit a non-return valve between the mechanical pump & the T-piece for the electric pump so that the electric pump can't pump fuel the wrong way and that should it be accidentally turned on, the two pumps don't work against each other.
 

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Advice above is good. However, I've been fitting an electric pump in the engine bay to all four of my 105's for the past 12 years and thousands of miles in each, with no issues whatsoever, (see above a Mitsuba pump just fitted to a Spider, my latest acquisition.)
I personally wouldn't keep the mechanical one, but you obviously can if you prefer.
With an electric-only set-up, you can use a hidden on/off switch to use as an anti-theft device if you like.
I
 
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