Conversion to alternator- electronic fuel pump question

Hi all,

I have the engine out so also decided to make the switch of generator to alternator and positive earth to negative earth.

I vaguely recall someone saying that the polarity change would require a new fuel pump. Is that correct?

I know I need to swap electronic ignition and modify the Tach but not sure why the fuel pump would need to be swapped out>

Robb

Rob,
You did not say which car you have, but as standard, Elans do not have electric fuel pump but mechanical driven off the Jack shaft. Yes the tacho will need an internal wire switching but if you are not clued up on this procedure give it to a specialist.

The change of wiring from dynamo to alternator is not all that complex but again if you are not familiar with the procedure, see a specialist. You will need to change the ammeter for a volt meter and remove the control box, connect the brown and brown and blue wires to a new battery feed cable of suitable load carrying capacity from the alternator. Again, consult an auto electrician if you are not sure. Get it right and things will be ok but get it wrong and you can cause a lot of damage!!
I have an early +2 wiring diagram marked up with the changes I did to mine, but the details will change from model to model. I presume that if your car is +ve earth then it is either an eary +2 or an S3 Elan or earlier.

Gordon

Rob,
I’ve just found my marked up Wiring Diagram. Hope it helps. Sorry for the state but it is old!!

Gordon


Thanks Gordon,

I have a 1965 S2 (built from 3 different cars- I thnk one was an S1). The (more car savvey than I) previous owner installed an electronic fuel pump when he did the re-build.

I will have the tach done professionally and have access to an auto electrician (and fire extinguisher!) as needed.

Thanks

Robb

I am a little hesitant to jump in here because I don’t have a wide experience of electric fuel pumps. However, you may simply be able to reverse the leads. The Carter pump I just installed has two terminals, one marked + and the other -, with no indication that either is connected to the case of the pump. (I’m already at negative ground so I didn’t give it much thought.) Other pumps may be “polarized” and assume that the case will be negative and the power supply positive. I would say that if your current pump has two terminals and the (+) terminal is not connected to the case, you’re OK to simply switch the leads. If it has a single supply lead and the case is assumed to be ground, you may need a new pump.

As far as the alternator is concerned, what are you switching to? Do you have a kit with instructions, or are you installing one from the junkyard? In the latter case, take a look at this article.

Robb,

I’m not sure Gordon is completely right.

As you know, your S2 did not come with an ammeter. Either did mine. A couple of years ago I converted to an alternator. At the time, I could have added an ammeter and/or a volt meter. I chose to add a matching Smiths ammeter and it works great.

Thanks andrew and Frank,

Andrew- I will double check the fuel pump, I am pretty sure I can just switch the wires. I am using and alternator kit from RD enterprises. Since I am doing this to avoid future trouble I figured that I would use a new alternator

Howard- You are right there is no ammeter nor do I have a voltmeter. An ammeter might be a good addition

Thanks

Robb