Lotus Elan

Fuel Pumps Manual or Electronic ?

PostPost by: billwill » Mon Apr 10, 2017 1:33 pm

I am considering mounting an inertia switch inside the cabin, perhaps on the back panel. It could serve both purposes there, a quick slap of the wrist would disconnect the electric pump and it would take a very knowledgeable thief to know that he/she has to press the rubber button to get the pump going.
Bill Williams

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PostPost by: pereirac » Mon Apr 10, 2017 2:19 pm

.. but you have just told everybody now. :-)

Some light aircraft have both mechanical and electric pumps. The electric one is used to prime the engine before starting and for the more 'crucial' stages such as take offs and landings.. Only slight problem is that engine fires are not unknown if you over prime the engine!

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PostPost by: alan.barker » Mon Apr 10, 2017 3:48 pm

For me Mechanical Pump with glass dome as original. + Primer Bulb for when the car has not been used for a while so i can prime Carbs.
If you fit one of the replacement pumps with no glass dome they seem to produce too much pressure. So you need to fit a pressure regulator.
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PostPost by: rcraven » Mon Apr 10, 2017 8:36 pm

I've had more than one replacement mechanical pump without the glass dome and have had no trouble with excess pressure.
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PostPost by: Quart Meg Miles » Mon Apr 10, 2017 9:46 pm

For whatever reason, my standard car won't run on modern alcohol laden fuels when it gets hot without an electric pump by the tank. I run both and have a regulator at about 1½ lb/sq" just before the Webers.
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PostPost by: 7skypilot » Mon Apr 10, 2017 9:57 pm

I use Facet (silver top) electric pumps on both the BD (Seven) and TwinCam (Elan) engines.

Both pumps have performed faultlessly for a total of over thirty years. Neither uses a fuel pressure regulator; the Elan has a driver accessible on/off switch. IMHO the advantage of quick electric fuel pressure outweighs the added complexity.

An option I certainly considered for the Elan was a primer 'bulb' to assist the engine driven pump but the familiarity and reliability of the Facet won the day.
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PostPost by: Oziswan » Tue Apr 11, 2017 9:41 am

Just a big Thanks to all of you that posted..

Our forum is something special..Great feedback.

Think the electronic is the way.. have had experience with them in other cars I have owned..MGA Twin Cam.
Currently use a pair in my 1934 Supercharged MGPA...and they are better in the boot pushing the fuel rather than in the engine bay sucking..

Will post another question next week on a new heading concerning this Elan I have purchased (why do I have a Floor mounted Dip switch incorporated in my wiring loom and also a steering column flick stalk for the headlights ??)..

Thanks again to all the help..
Cheers Ozi Swan
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PostPost by: elancoupe » Tue Apr 11, 2017 10:57 am

Keep in mind that Webers/Dell'ortos only need about 2.5 psi of fuel pressure. Depending on your choice of pumps, a pressure regulator may be needed.
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PostPost by: tedtaylor » Tue Apr 11, 2017 12:24 pm

Oziswan wrote:
Will post another question next week on a new heading concerning this Elan I have purchased (why do I have a Floor mounted Dip switch incorporated in my wiring loom and also a steering column flick stalk for the headlights ??)..


Funny you mention this as I just recently saw the same exact thing (but my mind is blank at the moment to figure out where), but i noted the same floor switch on an Elan. My thought was a Super Safety federal requirement?? If i find it, I'll post the picture.
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PostPost by: nomad » Wed Apr 12, 2017 2:01 pm

If you go electric go with the cylindrical Facet that Rohan mentioned. I believe they call it the "gold" pump. That design came from Bendix. I took one of those off of a friends junked MGB in about 1970. Before he had it on the MGB it was on an MGA. I fitted it to my MGB and a friend now owns that car. Pump is still going strong. They are indestructible or at least were when Bendix made them. Facet claims the same. That Bendix has way over 100K on it and 50 years.

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PostPost by: nomad » Wed Apr 12, 2017 2:03 pm

The "gold" isn't very noisy and had a cleanable filter on the bottom as well. And, no, I don't work for Facet!! :mrgreen:

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PostPost by: Geoffers71 » Wed Apr 12, 2017 3:28 pm

I've wrestled with the issue of replacing the mechanical pump with an electric one, but only because I'm tired of having to top up the carbs with a dash of fuel before trying to start after prolonged non use. I've tried priming using one of those rubber hand priming pumps, which worked fine to start with, but is now as hard as the devil's toenails and thus useless. So I've decided to stick with the mechanical pump, but use a cheap electric pump to do the initial priming and wire it so I can switch it off before trying to start the engine. Trouble is my car (S2) is positive earth and many of the pumps, e.g. facet, available state negative earth only. Nevertheless I've bought a real cheapo one, under £10, that doesn't specify + or - earth, I figured out I could get round this if it wasn't solid state. Here's what I've bought.
img_1099.jpg and


I'm happy just to try it out by reversing the red/black wires, but before I do I thought I'd ask on here for opinions before I wreck the pump. After all a tenner is a tenner :lol: what do y'all think?
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PostPost by: Quart Meg Miles » Wed Apr 12, 2017 4:05 pm

Geoffers71 wrote:.... Trouble is my car (S2) is positive earth and many of the pumps, e.g. facet, available state negative earth only. Nevertheless I've bought a real cheapo one, under £10, that doesn't specify + or - earth, I figured out I could get round this if it wasn't solid state. :lol: what do y'all think?

I've got a Facet in my positive earth S2 and it looks similar to your recent purchase. When they are plastic bodied they don't have a polarity, you just connect the Red (+ve) wire to ground and the Black (-ve) wire to your switch, as shown below.
posiflow-installation-105-496.jpg and

Even if it was metal all you'd have to do is mount it on an insulator with nylon screws and make sure nothing touched it.
Meg

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PostPost by: pharriso » Wed Apr 12, 2017 4:08 pm

So you power your pump to prime your carbs, then switch it off. Then you start the engine... can the mechanical pump suck fuel through this electric pump?
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PostPost by: alan.barker » Wed Apr 12, 2017 4:27 pm

I've done that on my TVR 3000S. Electric pump to fill carb then switch off. Turn Ignition key and Engine uses Mechanical Pump no problem. No noise from pump :)
Alan
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