Lotus Elan

Electric fuel pump mounting?

PostPost by: dcmarsh » Mon Nov 16, 2020 6:12 pm

Since I only start my +2S with Strombergs once every few months, it takes about 10 cranks of 30 seconds each before it starts firing. Once started, runs fine. Have replaced the mechanical fuel pump. Have read about folks who have put Facet electric pumps in the trunk to speed up fuel transfer in cases like this. Dumb question. I don’t see how and where it can be mounted in the trunk. Looks to me like you have to cut the fuel line coming out of the bottom of the fuel tank under the car and mount it somewhere under the car. What concept am I missing?!
1971 Elan +2S
1975 Elite 503
2005 Elise
1991 M100 (sold, regretfully)
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PostPost by: friedy » Mon Nov 16, 2020 7:31 pm

I have a facet mounted inside the boot, :D (trunk) on the rear wall. The fuel line comes from the tank into the boot through the rear wall, through a filter then the facet pump, then back out the boot and runs upto the carbs. Works well. I have recently put a glass filter in as the standard facet was getting blocked. In the photo you can see it is mounted above the earth points.
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PostPost by: Foxie » Mon Nov 16, 2020 8:18 pm

I replaced the mechanical pump with a Facet many, many, years ago. I bought two at the time, as I was told always carry a spare. But it never failed.

Also, the mounting instructions said it need to be mounted vertically.

Mine is horizontal, and never had a problem.

:)
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PostPost by: dcmarsh » Tue Nov 17, 2020 5:36 pm

4B74CB38-0472-4C35-A2AA-43297F4A366A.jpeg and


Thanks for the help, but to clarify, how did you get fuel line into the boot? It looks like I would have to cut the almost inaccessible fuel line under the car and attach 2 elbows, drill 2 holes into the boot, and extend the fuel line. Or is my Federal US Vehicle plumbed differently?
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1971 Elan +2S
1975 Elite 503
2005 Elise
1991 M100 (sold, regretfully)
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PostPost by: Bigbaldybloke » Tue Nov 17, 2020 10:01 pm

I fitted mine in the engine compartment under the carbs, and with the mechanical pump removed I used a flexible line to extend the fuel line to the electric pump, then remade the line from the pump to the carbs. This means you don’t need to touch the tank connection, although I did as I fitted a new alloy tank! Fitted under the carbs on top of the footwell, the pump is below the bottom of the fuel tank so no trouble with priming it. Not really used the car much since this change but it seems to work just fine. Also fitted an inertia switch to cut off power to the pump in the event of a collision.
Change is inevitable, except from a vending machine!
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PostPost by: kwhittle » Wed Nov 18, 2020 11:33 am

During lockdown I have only started my +2 once a month or so.
I WANT to churn the motor before starting as it ensures oil reaches the bearings !

Am I alone in this ??
Kevin
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PostPost by: bitsobrits » Wed Nov 18, 2020 12:58 pm

When rewiring my car, I configured it so I can turn over the starter without the ignition on for that very reason. Also have a separate switch for the fuel pump. So my procedure for a start after sitting for a few weeks is: crank on the starter only for about 5 seconds, then activate the fuel pump while cranking for another 5, pause, flip the ignition on and crank again. I get an instant start then, and instant oil pressure.
Steve

Elan S1 1963-Bourne bodied
Elan S3 1967 FHC pre airflow

Formerly:
Elan S1 1964
Elan S3 1966 FHC pre airflow
Elan S3 1967 FHC airflow
Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
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PostPost by: alanr » Wed Nov 18, 2020 1:21 pm

kwhittle wrote:During lockdown I have only started my +2 once a month or so.
I WANT to churn the motor before starting as it ensures oil reaches the bearings !

Am I alone in this ??
Kevin


Exactly..
So stick with the original mechnical pump which works perfectly ok IMHO.

Alan
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PostPost by: Andy8421 » Wed Nov 18, 2020 1:26 pm

kwhittle wrote:During lockdown I have only started my +2 once a month or so.
I WANT to churn the motor before starting as it ensures oil reaches the bearings !

Am I alone in this ??
Kevin

No, you are not. I have a cut out relay that cuts supply to the ignition and fuel pump in the event of loss of oil pressure on the car I race. I have this in place of an inertia switch as a safety precaution in the event of a crash, and as a bonus it cuts the engine in the event of a catastrophic oil pressure loss.

I do have an override switch, but when starting I normally just crank the engine until there is enough oil pressure to trigger the relay. This can take 10 or 15 seconds if the engine hasn't been run for a while.

There are commercial 'pre oilers' that ether store pressure from the last time the engine was run, or use an electric pump to pressurise the oil system before the engine turns over.

https://www.merlinmotorsport.co.uk/knowledge_base_articles/view/accusump-oil-accumulators-how-do-they-work-281

I believe F1 cars not only have their oil system pressurised before starting, but also have hot coolant pumped through the engine to bring it up to operating temperature before any attempt is made to turn the engine over.
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PostPost by: alanr » Wed Nov 18, 2020 2:37 pm

My thoughts are that I don't understand this obsession with fitting an electric fuel pump which I believe is so unnecessary. Stick with the mechanical one it works just fine and is not difficult to maintain and also keeps the originality of the car.
It is not a modern car engine built to modern tolerances so why try and make it behave like one? I guess it is because your modern day to day driver starts at the instant turn of the key that you feel the need to try and make your twincam behave the same way.
Personally, I really do want my +2 twincam to churn over a few times before it fires and starts. It gets the oil pumping around the engine at low revs helping engine wear and longevity.

Just my two penn'th..

Alan
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PostPost by: dcmarsh » Wed Nov 18, 2020 3:04 pm

Hmmm. Maybe I have some other problem then? Agree with cranking to get oil pressure, but 5-10 mi utes of cranking, draining even a brand new battery and requiring a jump to start it seems a bit much. After the laborious starting process, it runs fine, Have rebuilt the carbs so can’t think of any other problem. Can’t imagine ignition would cause this.
1971 Elan +2S
1975 Elite 503
2005 Elise
1991 M100 (sold, regretfully)
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PostPost by: alanr » Wed Nov 18, 2020 3:27 pm

A properly set up Twincam engine shouldn't need turning over for 5-10minutes from cold! You definitely have a problem!
Unfortunately diagnosis of things like this are virtually impossible on a forum.

Alan.
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PostPost by: bitsobrits » Wed Nov 18, 2020 4:39 pm

dcmarsh wrote:Hmmm. Maybe I have some other problem then? Agree with cranking to get oil pressure, but 5-10 mi utes of cranking, draining even a brand new battery and requiring a jump to start it seems a bit much. After the laborious starting process, it runs fine, Have rebuilt the carbs so can’t think of any other problem. Can’t imagine ignition would cause this.


Having had Zentih-Strombergs as well as Weber's on various cars, I find that the ZS carbs can be more difficult on a cold start if the temperature compensators and choke adjustment are not spot on. Webers of course just need a few prods of the pedal for fuel enrichment, but the ZS carbs don't have an accelerator pump, so they rely on the choke.

You have eliminated the choke set up as a variable, then?
Steve

Elan S1 1963-Bourne bodied
Elan S3 1967 FHC pre airflow

Formerly:
Elan S1 1964
Elan S3 1966 FHC pre airflow
Elan S3 1967 FHC airflow
Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
bitsobrits
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PostPost by: dcmarsh » Wed Nov 18, 2020 6:34 pm

Good thought. Will check that. Thanks.
1971 Elan +2S
1975 Elite 503
2005 Elise
1991 M100 (sold, regretfully)
dcmarsh
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Posts: 40
Joined: 20 Jul 2017
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