MGB Fuel Injection

[John316m]

Hi,
I've not posted here for some time, but I am looking for some help and advice
I have seen what appear to be stock (other than having a return line fitted) MGB fuel tanks used with fuel injected engines.
These seem to have a single high pressure pump rather than a low pressure pump feeding an external swirl tank with the high pressure pump feeding off the swirl tank.
Is this how you do it ? If so do you have any problems with fuel starvation on acceleration or cornering ? Or has anyone suggestion for installing a swirl pot inside the standard tank
Many thanks

[BlownMGB-V8]

John, it has been done many ways and it all works, after a fashion, depending on your demands and your habits. If you rarely corner hard with less than a quarter tank it should be just fine.

Jim

[John316m]

Hi Jim,
Many thanks for the reply
Which have you found to be the  most effective, an in-tank or external pump ?

John

[BlownMGB-V8]

It's not a matter of effectiveness. In-tank has many advantages including quiet operation and reliability of fuel delivery but it is a big job to install. External is easier but more noisy and a little less reliable. External swirl pot is a sort of hybrid.

Jim

[Moderator]

One internal solution is shown here: http://www.britishv8.org/Articles/EFI-Fuel-Tank-Mods.htm
Other EFI fuel tank mods are shown here: http://forum.britishv8.org/read.php?2,31845
A particularly nice auxiliary tank/pump solution is shown here: http://www.britishv8.org/Articles/MGB-V8-Supercharger.htm

I hope to complete an EFI installation this winter. I'm leaning toward a solution similar to the first of these.

[John316m]

I had seen one and two, but not number three.
The first one was my first choice and is probable the was I will go. I did try to locate a similar pump in the UK but came to the conclusion it will be easier to buy one over there on our next vacation !!!!!
I am not sure if the tank will need to be spaced down from the trunk floor if I want to fit a remove able plate over the top of the pump
Thanks to all
John

[BlownMGB-V8]

A relatively popular  external solution was to use a marine fuel filter and modify it so it acts as a reservoir by adding an internal siphon tube and a vent line. The low pressure supply pump then keeps the filter full and a restriction in the return vent line allows it to have a reasonable duty cycle under low demand. I used this system with good results to feed my blown 215. Rail pressure was supplied by a Ford or GM chassis mounted external pump, with a separate return to the tank. It all fits neatly in a spare battery box liner, and although the volume of the screw-on filter isn't all that much (maybe a pint of excess capacity available above the siphon tube) it is enough to prevent starvation in turns.

I do not favor running fuel through the trunk under any circumstances. The trunk is vented to the cockpit, and if bulkhead speakers are mounted it is even worse. If you mount an in-tank pump, special efforts should be taken to keep the lines below the trunk floor, even if it means modifying the floor for them. I do favor the use of an access panel however as the need for fuel pump replacement should be anticipated. Lowering the tank may not be a very good solution, much depends on how it is done.

The MG tank was not designed for EFI and has no provision to puddle the last of the fuel. Therefore if you open the tank you should consider putting some form of baffles in it for that purpose. Pick-up location clearly should be at the lowest point, but side baffles to prevent the fuel from being able to slosh away from the pick-up are a good idea. They should be fitted with weep holes or clearance to allow the last bit of fuel to get to the pick-up

Jim

[John316m]

Jim,

Thanks for the help, I was trying to avoid using two fuel pumps, hence the request for information from the US where EFi on MGs is much more common.

As you may know the common practice over her is to run a low/high pressure system (even Frontline who are selling a limited edition of the MGBs which Mazda engines (which sell for around $75,000) use this system)

British Motor Heritage (who manifacture bodies/panels etc.) have all the parts to reproduce the RV8 fuel tanks which are designed for EFI and have an internal swirl pot, but after over 12 months of trying I cannot get a date out of them as to when they will actually assemble the tanks and sell them.

John

[MG four six eight]

The third one is my car and it worked well. That said, I had the aux tank spring a leak on the way back from Reno last year. It devolped a crack in one of the welds.
When we got home I decided to convert to the in-tank set up like example number one.

The plumbing runs through the trunk, but what I did was make a removeable sheet metal cover that fully incloses the fuel lines for protection and isolates the fuel system from the trunk. The cover is then sealed to the trank floor with a gasket as well.

When a plastic inclosed pump is used like the GM pump in the pics, you can run the tank almost bone dry ( I tried it!!) This is because the fuel return is routed back to the inside the plastic body. In the OEM application for this type of pump there usually isn't any kind of swirl pot or baffles, just a big open tank!

Bill

[John316m]

Bill,

Thank you.

I think I will go with number one (although I'm not sure what pump it will be yet).

As I will be centering the fuel tank it will not be that much extra work to modify the trunk floor to incorperate an inspection panel and some sort of "hump" to allow the feul pipes to be located under the truk floor.

I think I will fit the pump unit on the flat section of the tank (shown in the attached photograph) rather than having to make up a flat surface as in the example one.

[kstevusa]

Good decison John.   The reason I chose the location pictured in my install was that is the location of the stock pickup and also the lowest point in the Tank.  I wanted to have full use of all of the fuel.  The fuel pump module I used did not allow for a flexible pickup that could be moved to another part of the tank.  That was the sole reason for chosing the location I did.  Glad I did becuase this spring I made it to an interstate exit and coasted to within 75 yards of a gas pump.  Had to haul a gallon back to drive up to the pump.
SAFETY FASTER!

[John316m]

With the price of gas over here any that is left in the tank is an investment !!!!!!!!!!!!!!!!

[MG four six eight]

John

When converting to EFI, I recommend going with the newer style tank that has the serperate externial vent and canister (the one that hangs in the RR fender. As well as a non-vented fuel cap.
With EFI the fuel in the tank can get much warmer in hot weather, due to the return line cycling the fuel from the engine.
Under the right conditions (full tank, city traffic, hot weather) fuel can percolate out through a vented (or non-vented cap that dosen't seal correctly) on to the paint. I found this one out the hard way when it happened to me and blistered the paint on the car.
Most modern EFI vehicles use non-vented fuel caps with a carbon canister, additionally the fuel cap/fill is located much higher vertically than a MGB fuel filler cap.

Bill