Fuel pump wiring Options

[fall-apart-dave]

OK here's where I get really dumb. As some of you know, I'm halfway through a 914 conversion in my 1969 VW Baja Bug. The type 1 VW engine I took out had a mechanical fuel pump fitted in the engine. The 914 replacement engine is running twin carbs instead of the injector system, and as you all will know has an electric fuel pump rather than a mechanical one like the T1. My question to you is this.

How do I wire in the fuel pump? My initial idea was to wire it in with the + side of the coil so that it kills when I kill the engine. However, this would mean that the fuel pump is running whenever I turn on the ignition, which I fear might flood the engine unless I start the engine immediately. Because the T1 fuel pump was mechanical it only pumped when the engine was turning. Does the same apply to the electric pump? If so, how do I wire it up so that it only pumps when the engine is turning?

Cheers guys!

Fall Apart Dave

PS

Other than that, project going VERY well!

[SirAndy]

How do I wire in the fuel pump? My initial idea was to wire it in with the + side of the coil so that it kills when I kill the engine. However, this would mean that the fuel pump is running whenever I turn on the ignition, which I fear might flood the engine unless I start the engine immediately. Because the T1 fuel pump was mechanical it only pumped when the engine was turning. Does the same apply to the electric pump? If so, how do I wire it up so that it only pumps when the engine is turning?

always ON works just fine as the floats in the carbs will prevent the engine from flooding.
however, i would *not* recommend using 12V from the coil. you shouldn't put anything on the coil that doesn't belong there.

at a *minimum* make the connection fused, better even run it through a fuse *and* relay. switched 12V should be easy to get from the stock fuse panel. use that as a input for the relay to switch 12V from the battery. put a fuse in that circuit.
voila!

it also would be a good idea to have a return line to the tank (dunno if bugs have that) to cycle the fuel ...
(IMG:style_emoticons/default/smile.gif) Andy

[fall-apart-dave]

Cheers for that dude!

Ran the pump from the master "on" switch in the end (my bug has none of the standard wiring loom left as I bought it as a wreck of a husk, so all the wiring is custom). I have a missile switch as the master "on" along with a keyed on switch to stop scroats from nicking my car. The master on powers up a whole bunch of relays and switches power on and off to a whole bunch more, including the sound system, the lights, the coil, battery earth, everything in the car really except hazard warning lights, alarm, interior lights and horn. I just added another line into that circuit (circuit is already fused so don't need to worry about that!). I see what you mean about the pump being on, it clicks away for a few seconds then stops until I start the engine. It's running grump as hell just now (one cylinder only fires as you let teh throttle off) but that may well be down to the engine not being used or run much for a few months. Also could do with new plugs, and the petrol in the tank on the bug is 95 octane and has been stood for about 6 months so won't be great. I know I need to run at least 98 octane, so that will help once I drain the tank and refill. Just wanted to make sure the engine starts properly! Also have some better twin carbs to fit and get jetted properly, so she needs a rolling road session so I'm sure I'll sort it.

Cheers for the advice mate!

Dave