Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - In Tank EFI fuel pumps, need advice

I have EFI on my 3.9 Rover motor/MGB conversion.

I have had a "swirl pot" put into the fuel tank (at great expense) and I was running an external Bosh fuel pump. This was a little noisy in operation and sounded strained even though it was located below the fuel tank in the battery compartment (pretty much as per Rogers book) and used a 3/8ths feed line. This (new) pump chose to fail last night and I shall have to replace it. It did not have a filter in the feed line to the pump which may be a contributing factor, is a filter essential?.
I have concluded that since I already have a swirl pot/baffle in place, and since I have to buy another pump anyway then I might be better off getting an "in tank" variety as these are much quieter in operation and I'm beginning to think, more reliable.
The local guy who does alterations to fuel tanks is able to supply and weld in the Flanges (and fuel pumps) from a Nissan Patrol or Toyota Hiace but is unable to tell me what pressure these deliver. Is there any one out there who knows?
Does anyone know of a more suitable pump?. The pump has to be able to deliver at least 36 psi. and be no taller than 14 cm (the depth of the tank).

Peter, I can't quote any figures or stats, but I'd be looking at the Holden Commodore pump. I've heard of it being in V12 a replacement. Barrie E
Barrie Egerton

Peter - when I looked at my pre-pump filter after the conversion, it was full of metal filings even 'though the tank had been cleaned carefully. There was other gunk from the fuel too. I am aware of other (than the RV8) cars that have a pre-pump filter and guess it is pretty well standard with FI.

Remember, in-tank pumps are not without their problems either and need to be accessible. Try the SDI arrangement if you are keen to go that route.

I've run without a filter on the low pressure side for nearly 20.000 miles without ill effect on the pump. I can see that there could be a problem in the long term as the tank gets contaminated, but most cars seem to have a filter at the high pressure end.

I found the original pump noisy, and replaced it with a high pressure pump, and modified resistor from Rimmers, it seems to be quieter, my pump is on a bracket behind the back axle immediately in front of the tank, I also have a Golf GTi, and I can hear that pump pressurising up before I start the engine.

Michael barnfather

Hi there,

I am thinking of doing the same thing with an in tank fuel pump. I have a pump from a 1997 VW Jetta. This pump has a swirl pot included and feeds the return line into the swirl pot, which will help with starvation.

The height of this pump will fit into the MG tank. It has a strange VW specific mounting arrangement so I will have to craft up some mounting brackets.

I have some concerns about the output pressure. The Jetta has Motronic injection that requires about 60psi pressure. As you stated earlier the Rover setup is 36psi. I'm not sure if the fuel pressure regulator will be able to handle this difference. I will give it a try before I install it in the tank.

Hope this helps,

Best regards,

Andrew Moss

That makes sense as I recall that the first Holden Camera's (unsure of spelling) used the Jetronic system . It's likely that they "Holden" would use common parts. The problem is that I recall that the Cameria used a 33 psi fuel pump. I might call the Holden people and see if they can tell me for sure.
You're probably right about the filter. Initially I used one but it had 1/4 inch apertures and I took it out as an experiment to see if this would reduce the "strain" on the pump and make it less noisy (I also put in a resistor). The people who installed the "swirl pot" , "Brown Davis", used a Half inch take up as I requested however did not use a Half inch elbow for the attachment of the fuel line (as I also specifically asked for) . This restriction on flow might well be the cause of the strain.
There was no problem for about a week (sans filter) and then I refilled the tank on the fateful night and 27 km later everything went dreadfully quiet. This of course means I have two variables; was it the fuel or was it the "strain" on the pump that did the damage?. If I could be sure that it was the fuel I'd put up with the (minor) noise..
Since I can't be sure and that bosh pump DID make an irritating whine, I'm inclined to the in tank arrangement. Did the SD1 use an in tank arrangement? Does this pump fit an MG tank?
How did you get the pump to fit?, I orrigionally wanted to do this but the handbreak cable is too close to the tank.
I don't know what a VW jetta is, I expect that it has another name in Australia if it made it here. I will look at VW's from around 1997. It sounds Ideal, how does this pump fit into the tank? A big flange like a dinner plate? . I would not guarantee the figures but the bosh pump runs at 60psi on 12 volts(so I'm told) so that should not be a problem for the Rover motor. If it is a problem then maybe put a resistor in at the fuse box to slow it down? (0.5 ohm, 5watts

The best and simple way (for me)is to use the GM pump they come from 15 lb to 120 lb of pressure. These pumps can be mounted in the tank or externally.

A filter is a must, install filter between the tank and the pump. Injectors are very sentive to small dirt particles. It's better to mount this pump in the tank due to the fuel helps to keep the pump cool, thus lasting longer.

Opel uses the same pump (GM) In Australia any GM product will have the same pump. Price $80 US to
$130 US There are also after market pumps of the same construction as the GM.
Bill Guzman

Another option is to add a swirl pot to the passenger side battery box. I had one fabricated the size of a battery with 4 ports. Two at the top for a low pressure pump feed and main tank return. The lower two fed the high pressure pump and return from the fuel rail. 65, 3800 series II V6 roadster
Don Zeigler

Peter, forget about the Holden Camira. Go for the V6 Commodore 3.8 ltr.It's a similar size engine for starters. But as far as I know ,it's only an in-tank type & could be different from the GM one Bill Guzman suggests. Barrie E
Barrie Egerton

Guys, when i had the EFI in my V8 i used the VP Commodore V8 fuel pump and had the surge tank made from high grade aluminium ( all was located inside the boot)and i also used 2 filters, one before and after the pump,
never failed

The Sd1 uses an external Lucas Bosch pump, mounted near the rear axle, with an inline resistor on the electrical feed, and the filter is on the high pressure side, just before the fuel rail, in the engine bay where it can easily be replaced.

If you can get your hands on a Rimmers catalogue for the SD1, all will be revealed !!!, or I can send you a pic of my engine bay, showing filter position.

I tried to mount the pump as close to the tank outlet as possible, I had previously fixed it onto the battery box, but as the pump does not suck well, had difficulties drawing fuel over the axle to the pump, fixing it next to the tank, low ,means it's gravity fed, and now works fine.

To get it to the required level, I welded a bracket vertically from just in front of the tank, as you say it is a close fit with the handbrake rod, which actually rubbed against the bracket until bent to shape. The pump is somewhat lower than the handbrake cable, being on a level with the bottom of the tank.

I'm using an SD1 axle, and 15" wheels, so the levers on the backplate may be in a slightly different position from the standard V8 axle.
Hope this helps,
Michael barnfather

Thanks Michael,

I have retained the MGB back axil, with the supra gearbox the 3.9 ratio is OK . However the handbrake cable is unfortunatly much too close to the tank for a pump to fit. Perhaps I could attach a small metal block/pully and move it closer to the axil. Failing that, perhaps I could relocate to the dead space behind the rear wheel arch which makes for a short fuel line which I think may be the main cause of the improved performance of your pump because in theory the fuel should syphon over the axil.

There is Just room between the side of the tank and the spring, about 5mm clearance. However given the possibility of rear axil movement I'm concerned that this may not be enough, what do people think?

As you may gather I'm going to give the external pump another go based mostly on Roger and Bills remarks and partly on lazyness. I will try and find a large 1/2" appature fuel filter, maybe off a truck?, any suggestions?.
If the pump fails again I'll try the commodor pump.

Thanks all of you for your help. I'm sure that I could have done this motor swap without assistance but I'm also sure that it would have taken much longer, cost much much more and not be nearly as good.
And I've got to say that an MGB V8 is a VERY good sports car. A whole different kettle of fish compared to the 4 cylinder variety. I'm quite blown away by it.


I don't think I would risk it between the spring and tank, as you say, there is a certain amount of movement on cornering.

My handbrake linkage is an inch or so above the pump, and the bracket mounting the pump is between it and the handbrake rod, worst case scenario is the rod rubs on the flat surface of the bracket, which it did until I bent the bracket inwards towards the tank.....Is this a possible solution ?

Michael barnfather

Commodore V8, V6, These are GM products. The pump is the same as the GM in US or Opel in Europe. The pump can be use in tank or out. If it's going to be use out of the tank make sure it gets air to aid in the cooling of the pump.
Also check the fuel pressure, different pressure pumps look the same.
I have one that was mpounted in the same location as the original B, it has been in the car for 3 years and about 40k miles.

BTW Edelbrock makes a pump that looks just like the GM pump and it's design to work outside, also Mazda MX5 Miata fuel pump (in tank)looks like the GM pump. This pump is rated at 80 to 100 lb
Bill Guzman

The pump is working reasonable quietly now, but not without some difficulties. A local company INTERJECT make an external filter that is an external version of the internal filter like that found on the intake in mgb tanks. It has large diameter inlet/outlets and is a simple cylindrical plastic mesh. I did find ,however, that this filter must be placed upright with the inlet on the bottom (in a loop of fuel line), otherwise a vapour bubble forms in the filter which will every now and again be pulled into the outlet and break the syphon thus making the pump suck very noisily. I used half inch fuel line and drilled out stainless fittings as far as I dared.
When I was re-plumbing after finding out about the vapour bubble problem I had reason to examine the (transucent) filter and observed all sorts of debris. A clear cause of the initial pump failure. Like Roger I would say that without one you are taking a gamble. You've got to ask your self Michael, do you feel lucky! (Appologies to Dirty Harry).
All in all I'm inclined to think an in tank would have been cheaper, quieter and allot less trouble!
Next time for sure.


If you are in need of this type of FI information get the book titled Chevrolet TPI & TBI Engine Swapping. An excellent book that covers a lot of stuff that about FI systems. I use it all of the time (although by now most of it has been committed to memory). I have been swapping Chevrolet v6/v8 FI engines into Volvos. Ever driven a Volvo 200 series sedan with a FI Chevrolet v8 and O/D auto trans...? Oh yeah.... Alan

Yes, a 740 with a 5.7 (350 CI) TPI, a real screamer, but... Volvo is a Volvo, now if I oculd change the looks.

What I did on the 5 F/I that I have done is keep it easy to work on & reliabale. After you do the weld in a NEW tank you will get weld scale & trash. I washed my tanks 6 times & I still run a n.a.p.a. filter that is 1/2' in & out & I was changing the filter every now & thin for the pump will make a good bit of noise when the filter get durty & thin we go to the rover s.d.1, Jag or bosch pump. What I did is mount the pump were the chrome stock pump was on the B. I used the rubber mts. that hold the back muffler on the 4 cyl. B (the ones that have the 5/16 studs that come out of each end) & a 1" X 8" 1/4, alu plate. I mt. 1 rubber mt. at each end of the plate to rubber mt., to hold down the noise. Thin I drill the holes in the pan infront of the batt. were the old pump use to be Thin I mt. the rover pump to the alu. slat with a rubber exhaust hanger (with out the steel bracket) I use the rubber strip to hold down the noise. Thin to hold the pump to the alu slat with the rubber strat I use 4 of the H.D.nylon tie raps. I have over 75,000 miles on my G.T. & the pump has never given me trouble & when the pump makes noise I change the filter (15 min. job) to change the pump (20 min job). The rover, bosch, Jag. pump will go for 150,000 miles. I will hear the pump run (if I listen for it for the 3 sec.) when I turn the key on & I will never hear it when the motor starts. I hate the thought of pulling the tank to feplace the pump. And I run a filter after the pump, in the trans tunel.
Glenn Towery

I'll hunt up the book, but if Glenn is right about the long gevity of the bosh pumps(neat idea with the exhaust hanger!)I might not need it.
The car's running like a dream now.

This thread was discussed between 11/02/2003 and 19/02/2003

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.