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MG MGB Technical - Fitting an EFI tank + ancilliaries

Right, I'm currently fitting EFI to my MGB, so obviously need to change the pump/filters etc, and I guess the tank as well?

1) Is there such a thing as an MGB EFI tank to fit into the standard place? If so, where is it available from and how much? (I can't find one).

2) If the answer is no to the above, I want ot fit a fuel cell in the boot. As there are a few grey areas regarding fuel cells in the cabin in road legal cars (in teh UK anyway), can i lower the boot floor, and mount the fuel cell there? This would also help with CoG.

3) Have any of you guys fitted EFI, and if so what tank/pump arrangements have you used? I'm planning on using a Facet pump to lift the fuel to a swirl pot, the use a Bosch EFI pump/filter arrangement to the fuel rail. Return line will either go to the swirl pot or tank, haven't decided yet.

cheers
OT Hayter

Tim Fenna at Frontline sells lightweight 14gallon fuel tanks with integrated swirl pot, and feed and return pipes.

I have just fitted one for my EFI conversion. I also know a couple of people that have it fitted.

The tank costs approx £300.

I have just completed the plumbing, which included the following,

- standard Range Rover Bosche fuel pump attached very low on side of battery box.
- pre-pump filter attached to side of battery box above the pump.
-12mm hose from tank to filter to pump.
- standard mgb 6mm copper feed from pump to engine bay.
- Fuel Injection filter sitting on nearside bulkhead
- standard mgb 6mm copper pipe for the return.

I will shortly be putting pic's on the web site if that helps.

Also, I am currently running this EFI plumbing with Carb so I can get the car back on the road whilst I'm sorting out the wiring etc for the EFI manifold/plenum/ECU to go in.


Hope that helps.

Jim
j w mcglynn

...by the way, my car is a V8. The tank would fit any MGB, EFI or not and regardless of engine.
j w mcglynn

oof! £300 is a bit pricey for a tank don't you think?

Is it baffled and foam-filled (better be for that price!).

Just thinking a Jaz fuel cell is only about £150.

Does that tank come with a breather connection?

DO you ahve any pics of your car?

cheers

olly
OT Hayter

okay second thought - can I use the standard non-EFI tank that i have now and run the return line from the fuel rail to the anti-surge tank instead?

That way I don't have to buy a new tank or worry about a new sending unit etc.
OT Hayter

You could but you'd want a BIG anti-surge tank as you risk the fuel boiling when stuck in traffic as you are recirculating warmed petrol.
Steve Postins

Olly,

I've had one of the Tim Fenna supplied alloy tanks on my car for a couple of years. They are baffled but not foam-filled and there is no breather. The tank filler connects to the original fuel cap, which as you know, for the UK market, is vented. The tank is deeper than standard but attaches using the existing fixings; it also uses the original sender. Being deeper and obviously lower it is also venerable to damage and mine now has a dent where something has hit it or it has hit something. It’s nice having the extra range between fill ups.

Geoff
Geoff King

I saw pic of an MGB GT recently that had a Range Rover tank fitted. The boot floor was cut open to allow it to protrude through, and the spare wheel replaced with a can of goo.

OT - £300 is a lot of cash, but I had a late tank with late sender, so had no where to return the fuel. An early tank and late sender would give me that, but that would mean a new "early" tank, plus a welding job for the swirl pot.

By the way, I got all my info from Geoff !

I will try to update my site tonight with pics of my bits.
j w mcglynn

Hmph, ok cheers for the info. Still a bit grey on this area and I need to get it right.

My car is a 1972 J-plate - will it have a 'late' tank?

J W McGlynn; if you had a late tank/sender combination, why didn't you just fit a surge tank to take care of the return line? I realise a bit more plumbing would be involved (and two pumps) but it would have been cheaper than the new tank!
OT Hayter

Oh, and Steve;

"You could but you'd want a BIG anti-surge tank as you risk the fuel boiling when stuck in traffic as you are recirculating warmed petrol"

I don't think I have ever heard that happening from anyone in a road car, track car or otherwise. The fuel may get a bit warm from some minor heat-soak from the engine, but boiling?!?
OT Hayter

Olly,
Don't know if you subscribe to Practical Performance car, but it's a great read and they've been running a series on aftermarket EFI. One of the writers tried recirculating to a surge tank a couple of issues ago:

"... most of the time this caused no problems but sitting in traffic could lead to fuel vapourisation....Half an hour with the boot open and the car would be fine. But half an hour on the had shoulder of the M25 isn't my idea of a good time."

Another writer is in the process of putting a T16 in a BGT...
Steve Postins

OT - I was going to fit a swirl pot, and have one in the garage, but then my LP Pump failed.
So I needed 2 new pumps, and made me realise that there would be two points of failure rather than 1.

j w mcglynn

I might be missing the point somewhere, but don't you just need a pipe in the tank to return to?

I bet you could dangle a pipe down the filler neck low down into the tank if you want a cheap solution, and solder the pipe in place (as I think the filler neck fits from outside. (or slice 2" out of the neck, fit the pipe & braze in place so it goes down into the tank, then use an extra rubber pipe to rejoin the slice to the neck.) This does end up with a fuel pipe inside the boot though.

Or just buy a new tank and braze a return pipe into it

My rangerover efi didn't need surge tanks, or two pumps.

There was a single in-tank mounted pump (you could use an EFI Cavalier, Granada or old BMW 3 series external pump low at the back) that fed the fuel rail (via a filter) at 4 or 5 bar tops, then the end of the fuel rail was a regulator- 3 bar or so, any extra fuel went straight back to the tank from the regulator, just to a spigot on the tank.

Worked well enough for 17 years.
Martin Layton

Try over on the V8 board, their are loads of threads regarding EFI fuel tanks,

1. Use a standard MGB tank and just make up an adaptor to go in the filler neck for the return or buy a Jaz or equiv tank with a fuel return. You can also use an ealy tank and a late fuel sender (or is t the other way around). Either way, it's the sender with a fule line included in its "lid".
2. Use a BIG fuel filter as the surge tank.
Connect th existing low prexsure pump to fill the filter from the tank then put the high pressure pump after the big filter.
See here
http://classicbroncos.com/efi.shtml
and here
http://bcbroncos.com/store/product_info.php?products_id=119
and here
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=12795and here
http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=36&subjectar=36&thread=2004041700580314982
Regards
Tony
Tony Bates

Oops, I screwed up the third thread, please delte the "and" at the end or just go here
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=12795
Tony Bates

Tony - great sites. Very useful.

Martin - yes and no. There's the other debate of whether you need a swirl pot or not. Some say yes, others say no, others say a big filter is enough.

Lots of ways and lots of great opinions.

I went my route just because the new specially made tank is neat (feed and return pipes and in built swirl pot) AND big. And because 1 pump means 1 point of failure. And because it's what Geoff did !

Jim
j w mcglynn

OT - I have added some pictures to my site, if they are of any use?

http://www.jimmcglynn.pwp.blueyonder.co.uk/engine/efi/plumbing/index.html

Jim
j w mcglynn

Olly,

Your ’72 will have a late tank and you could fit an early sender to obtain the flow and return, but you still need a surge tank or swirl pot so the pump doesn’t get starved when the fuel level is low. A large filter appears to work as a surge tank and you could fit the filter between the tank and the pump, then a second HP filter between the pump and the fuel rail with the return from the fuel rail to the early sender. With the HP pump mounted as low as possible, like Jim has, you shouldn’t need a LP pump.

Martin,

The Range Rover has a swirl pot inside the fuel tank; the pump fits into the swirl pot.

Geoff
Geoff King

Here is another alternative on a '74 MGB.
http://home.comcast.net/~whaussmann/Bosch_MGB/fueldelivery2.htm

werner haussmann

Hi!
When i converted my car to EFI i spend one year trying to figure out a misfire that started at about 13 minutes on my ride.

I tried and replaced everything including the EFI system. and after a year i discovered that my problem was the small fuel filter inside the feed line in the fuel tank.
that filter does not have the volume capacity for EFI use, dont forget to remove and you dont need any swirl pot without that filter.

Thanks.
Luis Rodriguez

Fuel supply- After trying a variety of set ups of varying degrees of complexity, expense and difficulty, I found the following to be the most effective. Easy to set up, quiet, reliable and cheapest. The very late model fuel guage sender may be fitted to earlier tanks. It has a fuel uptake line in it. Run a fuel line from this to a very large, beer can size, fuel filter. Run a fuel line from the filter to a 'feeder pump'. Run a fuel line from the feeder pump to the main high pressure pump. Thence to the engine and from there back to the old fuel uptake on the tank.

These are all standard, 'off the shelf parts' so they may be replaced with ease (and speed) if the need arises. As has happen to me when I needed to replace a fuel tank in a hurry.

The big filter (less than, $20 Kmart) acts very effectively like an antisurge tank, as well as protecting your fuel pumps and injectors. I'm using a Bosh fuel pump as the main high pressure pump The feeder pump is made by Peirburge and it's part # is 12001. Available everywhere. This feeder is a high volume, good suction, pump and can pull through a filter up to half a meter above the top of the tank. This means you can stash the filter and two pumps in the boot if you like.

Why use two pumps? There are two main factors-
A-High pressure delivery fuel pumps deliver good pressure but they are very bad at sucking the petrol to them, especially though the very necessary filter. If stressed they will cavitate noisily and wear out fast, even if they are managing to get fuel to your engine under those conditions.
Conversly a strong suction pump won't deliver the high pressure.

B-Unlike water, petrol has a very high vapour pressure and so obviously does not siphon well. This compounds the poor suction issue. After it has been around the hot engine and been released though the pressure valve it will also have developed lots of tiny vapour bubbles. The initial boiling point of petrol may be as low as 16degC which gives you an idea of the problem. Any EFI fuel delivery system must have a way of venting off that vapour. Running the petrol back though the tank is the best way of doing this. Allot of these light fraction (butane etc) bubbles also redissolve back into the main bulk of the petrol.

The government regulations for vapour pressure have allowed an effective increased of about 20-30 KPa here in Australia in the last couple of years which makes the problem even worse!

I have never had any problem with lack of fuel pressure, even when the tank has been down to less than 7 litres. I know this because when I had to replace a tank I only had 7 litres in a jerry can to fill the new tank. I then gave it a pretty good work out on the way to the petrol station.
If however you do decide to put in an external swirl pot (for whatever reason!) you have not wasted any money because you still need a feeder pump.
Peter

This thread was discussed between 25/10/2006 and 26/10/2006

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