96 replies to this topic

[The Batman]

pump first stage fills a 'bucket' where the second stage is submerged and gets it's fuel from so there's about a 1.5L buffer and as a result it often makes fuel starvation in corners much worse

correct and incorrect there, it is know where near 1.5L reservoir, it is very small maybe 0.5L

the key is to 2 holes in the bottom of the sender reservoir about 10-15mm big per hole

[Arno]

Where is this bucket?

it's the outside housing the actual pump sits in.

The OEM pump is a 3stage design to work with this housing:

- 1st stage impellor sucks fuel through the outside filter sock/strainer and dumps it's fuel inside the plastic housing.

There's an overflow at the top, so any excess fuel is returned to the tank once the ousing is completely filled.

Non-return/umbrella valves in the housing also allow fuel to get into this storage area from the bottom when the housing is being emptied if the first stage were not to work properly.

- 2nd stage impellor draws fuel from the storage area inside the housing and draws it further into the pump.

- 3rd stage turbine pump pressurises the fuel and sends it up and out the connection to the fuel pipe

The return line from the engine is fed back into the fuel storage inside the pump.

A walbro or similar AFAIK does not have the 3 stage design, but only a 2-stage, so it won't use the intermediate space in the housing as a buffer. Either it sucks fuel directly from the tank connection, or using the non-return valve system to passively fill the secondary storage to draw from there.

Both cases don't bode well for fuel starvation while cornering as this setup allows very little buffer-time compared to the OEM pump, which can already be overwhelmed by high power (read: fuel hungry) engines in long turns.

Bye, Arno.

[The Batman]

the information that i posted above is what GM tell to do when changing the fuel pump in the performance build book

[cnrandall]

I'm with Arno on this... far better to fit an Aux swirl pot and high pressure pump :-)

[Mike (Cliffie)]

I'm with Arno on this... far better to fit an Aux swirl pot and high pressure pump :-)

So this internal Walbro and a swirl pot?

[Mike (Cliffie)]

Where is this bucket?

it's the outside housing the actual pump sits in.

The OEM pump is a 3stage design to work with this housing:

- 1st stage impellor sucks fuel through the outside filter sock/strainer and dumps it's fuel inside the plastic housing.

There's an overflow at the top, so any excess fuel is returned to the tank once the ousing is completely filled.

Non-return/umbrella valves in the housing also allow fuel to get into this storage area from the bottom when the housing is being emptied if the first stage were not to work properly.

- 2nd stage impellor draws fuel from the storage area inside the housing and draws it further into the pump.

- 3rd stage turbine pump pressurises the fuel and sends it up and out the connection to the fuel pipe

The return line from the engine is fed back into the fuel storage inside the pump.

A walbro or similar AFAIK does not have the 3 stage design, but only a 2-stage, so it won't use the intermediate space in the housing as a buffer. Either it sucks fuel directly from the tank connection, or using the non-return valve system to passively fill the secondary storage to draw from there.

Both cases don't bode well for fuel starvation while cornering as this setup allows very little buffer-time compared to the OEM pump, which can already be overwhelmed by high power (read: fuel hungry) engines in long turns.

Bye, Arno.

Is the OEM tank this badly baffled?

[techieboy]

Is the OEM tank this badly baffled?

I don't think there is any baffling at all in the standard tank. Luckily I've got the ProAlloy tank with the baffling and one way valve. Hoping that will work with the new pump as I desperately want my missing revs back.

[The Batman]

as I desperately want my missing revs back.

no you dont

[Mike (Cliffie)]

Is the OEM tank this badly baffled?

I don't think there is any baffling at all in the standard tank. Luckily I've got the ProAlloy tank with the baffling and one way valve. Hoping that will work with the new pump as I desperately want my missing revs back.

Standard tank is baffled, it has vertical plates welded inside, I am not an expert in baffling though.

Maybe Arono or Chris could give us more of an insight to make sure.

[cnrandall]

I'm with Arno on this... far better to fit an Aux swirl pot and high pressure pump :-)

So this internal Walbro and a swirl pot?

I run a completely stock tank/pump then an external swirl pot feeding a bosch high pressure pump. Works well for 420bhp in race use.

[Zoobeef]

I'm with Arno on this... far better to fit an Aux swirl pot and high pressure pump :-)

So this internal Walbro and a swirl pot?

you would still need another pump after the swirl pot

[Duncan VXR]

Is the OEM tank this badly baffled?

I don't think there is any baffling at all in the standard tank. Luckily I've got the ProAlloy tank with the baffling and one way valve. Hoping that will work with the new pump as I desperately want my missing revs back.

Standard tank is baffled, it has vertical plates welded inside, I am not an expert in baffling though.

Maybe Arono or Chris could give us more of an insight to make sure.

Found this out when trying to get the fuel out with the tank in situ - well after when I looked lol

Short of cutting one open if its just the vertical ones it explains why heavy cornering with less than a 1/4 tank can get fuel starvation issues. I found the forge tanksoved my issues - well until the pump was not upto it on its own.

Be good to see the feedback on the new pump option - some good info in this thread though

DG

[Mike (Cliffie)]

Where is this bucket?

it's the outside housing the actual pump sits in.

The OEM pump is a 3stage design to work with this housing:

- 1st stage impellor sucks fuel through the outside filter sock/strainer and dumps it's fuel inside the plastic housing.

There's an overflow at the top, so any excess fuel is returned to the tank once the ousing is completely filled.

Non-return/umbrella valves in the housing also allow fuel to get into this storage area from the bottom when the housing is being emptied if the first stage were not to work properly.

- 2nd stage impellor draws fuel from the storage area inside the housing and draws it further into the pump.

- 3rd stage turbine pump pressurises the fuel and sends it up and out the connection to the fuel pipe

The return line from the engine is fed back into the fuel storage inside the pump.

A walbro or similar AFAIK does not have the 3 stage design, but only a 2-stage, so it won't use the intermediate space in the housing as a buffer. Either it sucks fuel directly from the tank connection, or using the non-return valve system to passively fill the secondary storage to draw from there.

Both cases don't bode well for fuel starvation while cornering as this setup allows very little buffer-time compared to the OEM pump, which can already be overwhelmed by high power (read: fuel hungry) engines in long turns.

Bye, Arno.

Arno,

The OEM pump is not three stage, only two as is the replacement pump and as it retains all the original in tank fittings and resevoirs it is a straight forward swap and upgrade. The fuel storage unit you talk about is not in the pump but in the pump housing which is retained in this uprated set up.

The kit is now ready for purchase at £86.90 plus VAT with free P&P if ordered from Glencoe.

[markiii]

good to know is yours in yet?

[Arno]

The OEM pump is not three stage, only two as is the replacement pump and as it retains all the original in tank fittings and resevoirs it is a straight forward swap and upgrade. The fuel storage unit you talk about is not in the pump but in the pump housing which is retained in this uprated set up.

Correct. The OEM pump sits in a plastic housing. It's first stage sucks fuel from the main tank and dumps it in the housing. This overflows constantly as it's open at the top. The second stage now sucks the fuel from the housing into the pump body itself and feeds the high pressure stage and out towards the engine.

We could probably debate the number of stages (2 and 3 can be viewed as being 1 and the same), but so far all replacement pumps I have seen (eg. Walbro, BOSCH, etc.) which fit in the original housing only have one suction feed and this is immediately pressurised and sent out to the engine.

Unless there is now a new pump available, the uprated ones all lacked the initial stage which the OEM pump has and which fills up the canister the pump sits in.

The above mentioned pumps rely on the umbrella-valves in the bottom of the housing and the return feed from the engine to fill the canister, or some simply do not use the fuel in the canister at all and suck it directly from the tank.

The Lotus service notes on the S2 elise have a nice diagram of the OEM pump operation. I'll see if I can scan 'em..

Again.. If someone has found/designed a pump that does retain the active filling stage of the housing/canister the pump sits in like the OEM then more power to them and I hope they sell lots of 'em!

It's just that various 'upgraded pumps' have been marketed for the Elise for some time on-and-off and so far they all failed to deliver enough fuel in conditions where the OEM one does keep the engine supplied with fuel, eg. when cornering hard.

I'm not trying to imply that this new pump suffers from the same problems as earlier attempts on getting a higher capacity pump installed.

Bye, Arno.

[kipper]

Interesting thread. Can anybody think of any downside of fitting the Glencoe pump with say, with only a stage two tune? I'm going to be fittting my Pro Alloy tank in the next couple of weeks and wounder whether this might be a worthwile upgrade while the tank is out, bearing any future mods to higher power levels? Following the discussions, there does not seem to be a concensus as to the advantage of this pump upgrade. When dropping the tank is there enough spare wire in the loom to allow the tank to drop below the chassis level, before disconection or does the wiring to the pump have to be disconnected through the inspection port, which I beleve is acessed form the pasanger compartment? Thanks Dave

[techieboy]

Can't see a problem with fitting it and having spoken to Jon at Courtenay's, he's pretty sure it's a good swap although he did want to check one small point with it. I'm certainly going to fit it and will be on the phone to Glencoe again tomorrow (thanks for the reminder). I've got no choice, I need to fit a new pump whatever, as mine is not capable of coping with the engines fuelling demands and Courtenays have had to decrease my rev limit to protect the engine. They do wear out with time and whilst I could fit a new OE pump that would be good to circa 300bhp, this is a cheaper and more capable replacement and gives me headroom for a Harrop or whatever, in the future. No, there's no slack in the loom to allow you to drop the tank as there are also hard fuel lines from the pump that go through the firewall to the engine bay. If you can get the car fully into the air, you can reach up to where the fuel lines and loom connect and disconnect them. But, you'd be doing it blind and by touch alone. The fuel line connections on the pump housing are a little fragile, as I found out to my cost, and are easily snapped. Definitely better to take the seat out and go through the access panel. Will also be a good chance to enlarge the access hole so that you can remove the pump and upgrade/replace it at a later date, without dropping the tank.

[kipper]

Can't see a problem with fitting it and having spoken to Jon at Courtenay's, he's pretty sure it's a good swap although he did want to check one small point with it. I'm certainly going to fit it and will be on the phone to Glencoe again tomorrow (thanks for the reminder). I've got no choice, I need to fit a new pump whatever, as mine is not capable of coping with the engines fuelling demands and Courtenays have had to decrease my rev limit to protect the engine. They do wear out with time and whilst I could fit a new OE pump that would be good to circa 300bhp, this is a cheaper and more capable replacement and gives me headroom for a Harrop or whatever, in the future.

No, there's no slack in the loom to allow you to drop the tank as there are also hard fuel lines from the pump that go through the firewall to the engine bay. If you can get the car fully into the air, you can reach up to where the fuel lines and loom connect and disconnect them. But, you'd be doing it blind and by touch alone. The fuel line connections on the pump housing are a little fragile, as I found out to my cost, and are easily snapped.

Definitely better to take the seat out and go through the access panel. Will also be a good chance to enlarge the access hole so that you can remove the pump and upgrade/replace it at a later date, without dropping the tank.

Thanks, good deal of pointers there, Techie.

So as usual more complex than I initially thought. Getting the car in the air is a bit of a problem in my garage, well any garage. Have been trying to source some expandable ramps..some on Ebay, hydraulically pumped which seems a bit of over kill. Looking at some manually screwed types which are a bit cheaper, but still quite expensive. These ramps give between 16 to 20" lift ,which I assume is enough space to drop the standard tank and fit the Pro Alloy tank.

Back on subject, there must a seal of some form (I know I should consult the TIS disk ), O ring, which will need to be replaced between the mounting flange on the tank and the pump housing?
Enlarging the access panel would also mean enlarging the closing plate and possible repositing of the plate securing points?

Off to find TIS disk

Cheers

Dave

[techieboy]

Yep, there is a large O ring between the pump and the tank. Not sure if it's reusable or whether the Pro Alloy tank comes with a new one, as I bottled it and got Courtenay's to fit mine. Just wish that I'd had the foresight to enlarge the access hole when the tank was out. Just trying to pluck up the courage to do it now with the tank in-situ.

[theolodian]

Yep, there is a large O ring between the pump and the tank. Not sure if it's reusable or whether the Pro Alloy tank comes with a new one, as I bottled it and got Courtenay's to fit mine. Just wish that I'd had the foresight to enlarge the access hole when the tank was out. Just trying to pluck up the courage to do it now with the tank in-situ.

The main wiring harness is taped up and over the tank. If you use a nibbler and take it easy then you should be fine, but don't just hack away with any kind of saw.

Or you could use a plasma cutter, not.