Installing electric fuel pump

Post by **jtbo** » 20 Jul 2006 03:07 pm

I was thinking to use one of pumps I currently have set up for carb, it is type of pump usually used in carbs so no problem there.

But I have been thinking how to wire it, currency is ok, that is easy part, it goes from battery via fuse to relay and there to pump, but what about pull up for relay?

I don't like it pumping fuel when key is in ignition and engine is not running, but where can I get pullup for it that pulls up only when engine is running?
Naturally pullup will go trough switch in cockpit to cut power in case of problem/emergency.

Post by **foggyjames** » 21 Jul 2006 03:22 am

The benefit of having it run with the ignition on is instant starting

I think you'd have to reference it to RPM (or perhaps charge voltage) to make it switch on when the engine is running.

cheers

James

Post by **willowdog** » 21 Jul 2006 11:04 am

My girlfreind used to have a Nissan 260Z that had a 280Z engine in it. They had ripped the Fuel Injection off and put two huge Hitachi carbs on it.

Dont know what the wiring was like (I assume a solenoid etc) but it used to kick the pump on for 3-4 seconds when you put the key to ignition but then run continuosly once the enigne was going. I stopped if you stalled the car.

Probably one of the better systems. Just need someone who remembers electronics better than I do!!

Cheers

Post by **Chris_C** » 21 Jul 2006 12:35 pm

What do you mean pull up Jani?

Dunno if it's what you are looking for, but I can show you how to rig up something to the oil pressure switch, that way it'd only run with the engine running. Could mount a cockpit switch as well for pumping a bit in before startup too, not sure what you'd need tbh, but the electronics part can be sorted.

Post by **jtbo** » 21 Jul 2006 01:10 pm

With carb I think it should not make much difference to starting as there should be gas in carb, but of course if car has stood long time it may help if pump will pump when there is power

That 3-4 second priming sounds like pull up has been taken from fuel injection fp relay pull up, my megasquirt does that, but I need to take it out for undeterminent time now

Oh yes, sorry for not clear terms, with pull up I mean that +12V signal to relay that activates relay causing higher amp power to go to device behind that relay, ehm. don't know correct word, sorry

I will put switch there for sure and perhaps just install it simple, so when ign is on it would start pumping as it seems rather complex to do anything else, or then I may indeed just use old mechanical that may not be in best possible shape.

I guess it is this way those are typically installed?

Post by **willowdog** » 21 Jul 2006 01:45 pm

That makes sense - taking power from the FI line - seeing as it used to be FI.

It was a hell of a lot quicker with the 2 carbs than FI (a freind had one) BUT we used to joke that it cost $5 just to start the engine. It seemed like it anyway, and that was back in '99 when fuel was 70c/litre (It's around $1.50 in Melbourne now I think - $1.80 here in NZ)

Cheers

Post by **havock** » 23 Jul 2006 01:52 am

Lets put this in same gatecory.
I think to buy cheap electric pump too from biltema because my mechanical is leaking.
If i put electric fuelpump to my 340gl, i will make switsh for it on and off style. First when start put pump on for 2-5 second then starting, Does this sounds smart, and can i leave "old" mechanical pump still engine or should i remove it and make somekind plate for hole?

Post by **foggyjames** » 23 Jul 2006 02:18 am

I'd remove the pump. An injection engine of the same age will have a blanking plate for the hole. Late injection engines (95+?) don't have a hole for the mechanical pump, hence no cover plate.

Make sure the pump you buy is low pressure (5-10psi max...most like 2-4psi) for carbs. FI pumps are more like 50psi. You can get a pressure reducer, but it's extra money.

cheers

James

Post by **jtbo** » 23 Jul 2006 11:56 am

Also there is two different pumps in Biltema, one is for installation close to fuel tank and other is for engine bay.

I have Bilteam product number 523226 and it is located to engine bay.

I left old mechanical pump on place when I did my fuel injection conversion, just put one hose to it so no dirt would go into and also put little gasoline so it won't run dry. Seemed still to work after one year.
However what James says is sure better option.

One thing you may notice when you have installed electric fuel pump is smell of petrol, as it pumps more fuel constantly than old mechanical pump, those old fabric covered fuel hoses leak more and you can notice that specially in fuel return line as it has not been so much in use with mechanical pump.

Also you can put new mechanical pump if you like, it costs about 7€(cheap model) from Motonet, quality model costs around 20€

I was planning to install same way, with a switch, but I then decided to make original way, maybe I change all other things to original soon