Cranking Engine For Fuel Supply

[billwill]

Can anyone confirm my previous question that if the glass fuel pump bowl is half full would that suggest that the valves in my pump are working ok??

If that is the state of the pump after a 2 week period of inactivity, then probably yes, the valves are working ok and not leaking much.

[billwill]

Where are these valves? I have taken apart many Elans, Changed many fuel pumps and I don't recall ever seeing valves.


What about putting in one of the new mechanical fuel pumps.....I don't recall seeing valves in those.

I am confused.

Tony v

All diaphragm pumps have to have one-way valves at inlet and outlet or they simply wouldn't work.

[nmauduit]

Where are these valves? I have taken apart many Elans, Changed many fuel pumps and I don't recall ever seeing valves.

the valves are pressed fit into holes at the bottom of the top half of the pump, see Gary's post at :

lotus-carbs-f40/fuel-pump-overhaul-t22958.html

one can check the operation of the mechanical pump by having it briefly pumping into a can rather than towards the carbs, then assess the amount spurted by each stroke. When fitting a kit, make sure the valves are set right (i.e. for pushing the fuel towards the carbs).

[elanner]

William,

It all sounds pretty normal to me. The fuel pump bowl is rarely completely full - at least mine isn't. There's usually some air sitting at the top. Half full seems a little low but it changes constantly so check it a few times (and see if the level goes down when the engine is left standing - which I guess would be a good indication of the input valve leaking fuel back down to the tank).

Presumably if there was anything wrong with the pump valves the engine wouldn't run well due to starvation? There's really nothing in the valves, just a small flap - not much to go wrong.

After two weeks my engine took some cranking too, so I fitted a primer bulb, which fixed the problem nicely. I'm always a bit surprised that fuel manages to evaporate from the carb float chambers without any attendant smell, but that seems to be what happens. All that recent hot weather in the UK must be the problem!

As a general check I would look at the fuel filter in the carbs (I assume Dellortos have a filter). Dirt in the fuel could presumably upset seating of the pump valves.

Nick

Edit: Here's the picture from the boot strut discussion we had a while ago!

Primer bulb

[William2]

I decided to go down the avenue of fitting a fuel primer bulb in the boot like several other owners have recommended. Absolutely marvellous, a few pumps of the bulb and the engine fires straight away. Previously if the car was left standing for 2 weeks or more (not unusual at this time of year) I had to crank the engine over for what seemed like eternity to fill the Dellorto carbs. Like others have commented already this will save a lot of wear and tear on the flywheel ring gear, starter motor and the battery. Total cost ?6.00!! My only slight reservation is how well the rubber bulb will stand up to modern ethanol fuels.

[tvacc]

Here in Buffalo NY we have several stations that offer non-ethanol pumps. A bit more money but worth it.

I don't know where you are located, so I don't know if your area gives you that option.

I use http://pure-gas.org/

That tells me where the non-ethanol gas stations are located.

Tony V

[gus]

I'm betting on the carb floats being too low. Mechanical fuel pump makes it worse but there should be enough fuel to start the car. If there is not enough fuel that a couple kicks of the gas won't at least make it try, it is no the fuel pump's fault

[Geoffers71]

I'm familiar with the fuel evaporation issue and I have the same problem with starting my S2. I fitted a rubber primer bulb in the fuel line in the boot (trunk) and issue solved. However, as part of the process of trying to locate the source of a fuel smell in the boot I removed the pump and then had to resort to the usual practice of hand filling the carb bowls before attempting to start the car. So it's been a few months and I decided to refit the rubber bulb, but when I found it again it was ROCK HARD !! The rubber pipes used to connect the pump have also lost their flexibility and they are R6 spec. The bulb has absolutely zero flexibility at all and it was new when I fitted it originally. Is THIS one of the effects of ethanol fuel? Anyway there's no way this can be used again so I'm stuck with hand priming again, which is a pain in th a**e. I thought I'd fit one of those Facet pumps to use solely for initial priming, not all the time just to prime then switch off, but the ones I'm looking at state "negative earth only". Can the wiring simply be reversed to use it on a positive earth system?
Bit worrying if ethanol is the cause. What is it doing to other parts of the fuel system?
BTW I always use 97 octane fuel from one of the main suppliers ( Esso, Shell, Texaco) as I was informed this was unlikely to contain as much ethanol and in some cases ( Texaco?) none.

[William2]

I will have to see how I get on with my primer bulb long term. I try and use BP Super Unleaded because I have been told that in the UK it currently does not contain ethanol.

[Grizzly]

Can anyone confirm my previous question that if the glass fuel pump bowl is half full would that suggest that the valves in my pump are working ok??

Sorry missed that post, i fitted new valves to my car to fix a very similar issue. Looking at it now and knowing my car starts quite easy from cold, the glass bowl stays full with a slight bubble at the top for a week or so (not really left it longer than that un run) more importantly if i slacken the hose off the carb i get fuel after one revolution of the engine.

When it had bad/leaking valves the fuel level would drop to the height of the brass filter (about half way down the glass bowl) i could crank it as much as i wanted it wouldn't start until i primed the Weber Bowls with Fuel. If you loosen the Carb hose as before you won't see any fuel for a good few revolutions if ever.

Strangely this is fairly common with these pumps, because the one way valves are staked in they often get left when people fit the kits. One word of warning, when you tap the new valve in they are very soft and it's very easy to damage them so you need to make sure they are air tight before refitting to the car (also don't forget to fit the little gasket under the valve)

If the Fuel pump is working correctly there is no need for a Fuel Bulb.

These are the one way valves and they live in the top half of the alloy casting above the diaphragm.

Library picture of Google

[vincereynard]

I wonder if one of these would fit?

http://www.mayhilltractors.com/index.ph ... uct_id=542

Glass bowl, brass filter and a built in hand primer!

[Grizzly]

I wonder if one of these would fit?

http://www.mayhilltractors.com/index.ph ... uct_id=542

Glass bowl, brass filter and a built in hand primer!

Ac made them similar to that, we have a Hillman Minx at work that looks identical from the outside but has a priming lever. I've not taken it off the car so couldn't tell you what the actuating arm looks like but knowing how easy they come apart i bet it could be modified to work.

[vincereynard]

I wonder if one of these would fit?

http://www.mayhilltractors.com/index.ph ... uct_id=542

Glass bowl, brass filter and a built in hand primer!

Ac made them similar to that, we have a Hillman Minx at work that looks identical from the outside but has a priming lever. I've not taken it off the car so couldn't tell you what the actuating arm looks like but knowing how easy they come apart i bet it could be modified to work.

I had the same on a Sunbeam Alpine. Which, after all, is a Minx in a party dress. It also incorporated a shut off valve in the inlet side. I asked them to sell me a suitable gasket so I could check the fit but had no luck.