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MG MGB GT V8 Factory Originals Technical - Rover Hotwire Fuel Injection Questions

I am in the process of fitting a Rover Hotwire Injection on my Buick 215 V8 and I have a couple of questions. I was able to get it to fit under the hood by milling off 5/8" from the bottom of the middle manifold that has the air tubes in it. My car is a '67 and when I put the Buick four barrel manifold on it 54,000 miles ago I was able to find the fittings to plumb the water tempature part of the safety gauge to the intake manifold at my local ACE Hardware store. I would also like to use the safety gauge on the Rover manifold and the sending unit screws in alright, but there is nothing inside the manifold for the bulb at the end of the tube to press againist so it will seal. This unit was made to fit onto a 4 cylinder B head. I would appreciate hearing from anyone who has plumbed the safety gauge to their EFI manifold.

I am going to tap the back of the manifold for one of the heater connections. I bought a 1/4" NPT fitting the has a 1/2" hose barb on the end. Looks like that is what a few others have done.

Another challenge is the bypass hose that goes into the back of the water pump. The Buick manifold is made so that the water outlet has a 5/8" fitting as does the front cover. The rover manifold has a 3/4" connection on the left side (facing forward) so I think I will buy or make a fitting that will marry the 3/4" to the 5/8".

I need to get a air filter. Can someone give me a part number of a paper filter or a K & N.

I'm planning to drive the car to Wisconsin for British V8 2008 and appreciate input from anyone that has converted to EFI.


Al Wulf
A. Wulf

Just thought of another question related to my EFI
project. What temperature thermostat? 160, 170, or 180

Thanks in advance,

A. Wulf


My lower manifold section has a tapped hole for the temp sender in almost the same place as the Buick intake. I installed the Bordon tube at that point with no other fittings. I am using a dual guage as well in my 1966.

You want to use a 190* thermostat. FI needs to run hotter than a carb.

I use a K & N cone style air filter attached to the end of the mass air sensor. Sorry I do not have a part number. Go the the K & N web site after measuring the diameter of the MAS and order a cone filter about 5" long. It will attach with a hose clamp.
Jim Stuaqrt

Thanks for the response. My temperature sender screws in OK, but the bordon tube is loose and won't seal. On the Buick manifold I was able to find the fittings at my local ACE to neck it down and I had to bore some of the material out so the bulb on the end of the tube would fit.

Tomorrow I'll buy a fail safe 190 and go to the K & N site.

Thanks again.

A. Wulf

Hi Al,
you need an adaptor,
they are available in the uk from The MG Owners club,
checkout their web site WWW.MGOCSPARES.CO.UK, part number 11k2846 about $6/$7 plus postage.
Hope this helps.


Thanks for the information. I was able to source an adapter from Paul Dierschow at Sportscar Craftsmen in Arvada, Colorado. Paul said he had a he uses them on 1275 Spriget engines. I will file away the part numbers in my personal files. I have everything hooked up, but have not been able get it to start or run the fuel pump through the injection harness. If I take it to the British V8 in Wisconsin I may have to put the carburator back on.

A. Wulf


Thanks for the information. I have just registered on the Land Rover Forum.
A. Wulf

What arrangement did you use for your fuel pump/fuel tank setup? I've got a whole new motor in my car and I'm still having some dodgy starting problems. The only things left to replace are the distributor and the fuel injection harness/ecu. (I have a spare of each).

I need to hook up a gauge and see what kind of fuel pressure I'm getting while cranking. Maybe it's dropping too low...

I am using a Airtex E8228 Fuel pump mounted on the outside of my battery box, the same place as where I mounted the 5.5 to 9.5 pressure pump for the 4bbl carburator. It was a Master E12S. I am using my original '67 MGB fuel tank with a return line plumbed it near the front on the passenger side. I did not put a swirl pot in the tank. When I have time I'll put the car on the lift and send a picture. I chose the E8228 because of the 5/16 lines and it has enough pressure and pumps 40 gallons per hour. You're a little ahead of me because I can't even get mine to fire or get the fuel pump to run from the injection harness. The fuel pump will run independent of the injection harness.

I think my problem is in the harness. I downloaded the 24 test procedures from the Range Rover site and will probably go through them and hopefully find the problem.

I'll send some pictures of what I've done so far. We just go back from the V8 meet in Wisconsin and another trip to Northern Minnesota.

The white plug which I think is the plug that doesn't have a home when removed from a Land Rover has the following wires.
1. Brown
2. Black/Yellow
3. White/Red
4. Purple/Yellow
5. White
6. White/Purple
7. Yellow
8. Black/Orange

If Rovers are wired the same as other British cars the Brown is Hot all the time, white/red is probably for the starter, white is the ignition, white/purple is the fuel pump. I only used the Brown, white/purple and the white.

2756 is the way I plugged into the negative side of the coil. I have a pertronix and there is a red wire going the positive side and a black wire going to negative side. The other red wire on the negative side of the coil goes to the VDO tach. Since the EFI wire wasn't long enough I had to add an extra wire as pictured.

A. Wulf


Another picture. This is the way I plugged the EFI harness to my cars system. Brown is spliced to a hot wire all the time with a 30 AMP in line fuse, the white/purple is spliced to a wire that goes to my fuel pump on/off switch. ( I know I should have a inertia switch) The white wire coming out of the plug is spliced to a wire that is live with the ignition switch on that I used to use for the electric choke on my carburator.


A. Wulf

I don't have the wiring diagram handy, but you must run the fuel pump from the relay in the Rover wiring harness. It is fine to put an inertia switch in line, but you should not run the pump outside the Rover harness. The injection harness keeps the pump shut off if the engine is not running, for whatever reason- wreck, out of gas, etc.

I found a spare diagram= white purple from the relay to the inertia switch and then to the fuel pump.

Don't forget the white/black wire that goes to - on the coil. Without it, the engine will not run. This the wire that tells the ECU the engine is running.
Jim Stuart

Al, the red/white lead has to be connected to the starter relay. It provides power to the pump while cranking. The ecu takes over once the engine is running. Barrie E
Barrie Egerton

not wanting to start an argument, as I do not know what system you are running, but I cannot find a red/white wire in the 14CUX harness, and the start up power comes from the ECU to the fuel pump relay, not from the starter relay.

To quote from the Rover manual, " the main relay is energized via the ECU when the ignition is switched on and supplies current to the fuel injection system. The fuel pump relay is energized by the ECU which in turn operates the fuel pump to pressurize the fuel system."

I have a battery + connection, an ignition hot (from the ignition switch) connection, several ground connections, and a - coil connection.
These are the only "outside" connections required. Aside from sensors, all other connections are within the FI system.

In actual operation, when the ignition switch is turned to "on", the fuel pump relay is energized for a few seconds, and then shuts off after building up pressure. It is turned off because the ECU does not receive a signal from the black/white coil wire to tell the it that the engine is running. When the switch turns to "start", the coil becomes hot, the starter turns, the injectors spray fuel and the engine starts. At this time, the fuel pump has power from the relay and pumps continuously, with the excess fuel returned to the tank.
Jim Stuart

Jim, I just double checked. The circuit I was looking at was for an '84 model.I don't have EFI any more. I've gone back to a carby. The system I used was wired as I described, but obviously from an older model.I remember connecting 4 wires from the EFI loom. Sorry for the confusion. Barrie E
Barrie Egerton

Yeah you kind of threw me on that one too. I started looking around my harness and couldn't find any such wire.

Why did you choose to go back to carby? I remember Jim Stuart having a little fun with me at a V8 meet for the problems I was having with fuel injection, and now he has converted to the dark side. =)

Justin, the EFI started to play up & I found it too hard to fix. The only way I could find was to substitute the parts & I didn't have that many spare bits. I did have a Holley 465cmf & an Offy manifold lying around so on they went.I haven't noticed any difference in performance, so the carby is staying put. Barrie E
Barrie Egerton

My roadster has a 14CUX system and I love it. There were some initial problems but you all got me squared away.

I am in the middle of fuel injection for my GT which has a Buick 300 engine. There are no FI intakes for the old 300, but I found a throttle body with 4 injectors.

A few more weekends.....
Jim Stuart

I am happy to report that I got my car to start and run, today. It was a stupid thing, really. I borrowed another harness and on it I noticed a heavy black wire (10 gauge) and a black/gray wire (about 12 gauge) that attached to a ring terminal. Also, next to these two black wires were white and gray wires going to a a plug. On the harness I bought on Ebay all of these wires had been sniped off. When I asked the seller about it he said they weren't necessary for wiring to the MGB. I shouldn't have taken his word for that. I also noticed that in Curtis' write up on there is a black/gray wire from terminal 27 to ground. Neither of my other two ground wires were black/gray. Being around british cars as long as I have, I should have realized that whenever you see a black wire it needs to be attached to the body or engine.

As soon as I had everything hooked up right, turned on the key I heard the fuel pump run and when I moved the key to the start position it fired immediately. It idled smoothly at about 700 RPM. I put a 195 failsafe thermostat in and according to my dual gauge it warmed up to a little over 200. In Denver, today the outside temperature is close to 100 and when I got stopped in traffic it heated up to 212. When I shut off the engine and restarted it, it started almost as fast as did from cold. But, I did notice that it idled at 1200 for about 30 seconds and then went down to 800, which is where it seems to like to idle.

My harness doesn't have a place to plug in the Fuel Injection Fault Display, eventhough the seller included it with my harness. I may follow the instructions on Evan Amaya's web site and wire it in, but for now I think I'll just drive it.

Sorry to be so long winded, but I have a question. I have the ECU sitting on the passenger seat and I took the plug out behind where the petals would be on a right hand drive car and ran the wires through. Do you normally shorten the wires? They're really long. I like the way Jim Stuart has the ECU in the little parcel compartment on the right kick panel.

Finally, I would like to thank everyone who responded both on this board and by e-mail. Glen Towery was also very generous with information eventhough I have never bought anything from him.

Jim good luck with the 300 EFI project. Keep us posted.

Isn't this a great hobby! I love it when a plan comes together.


A. Wulf

Al, if you keep the Fail-safe stat and it reached the failure mode, you will get cold this winter. i had the same situation occur when i fired my car off first time. we did not wire up the fan until the engine got hot. next winter i was traveling on a chilly morning and noticed engine did not warm up much. i pulled the 180 degree stat and it was locked open. i went with a Mr. Gasket full flow unit. seems most of the high flow stats are made my Robert Shaw Co.. Just a hint of what could have occured if it reached the failure mode.
Look fwd to seeing you & Wife in N.C.
kelly stevenson

Congrats, Al!

I use Robertshaw 'stats, as well.
Carl Floyd

If I recall correctly, variation in idle speed is caused when the speed sensor is not used with the 14cux. I have the same thing and just got used to it. I find the instant starting somewhat disconcerting as sometimes I don't use the car for a month or so when I'm out of town. I'd rather have it crank for a bit when starting up after sitting a while. Another one of those "I'll get to it some day" items.

Anyway, I think you'll find the EFI very enjoyable.

Edd Weninger

"I find the instant starting somewhat disconcerting" I wish I knew what that was like. For 8 years I've had to crank away for 5-10 seconds to get it to start....

Kelly and Carl,
Thanks for the tip about Robert Shaw thermostat. I just bought one at Autozone and will put it in one of these days. If I had gotten it operational for the last trip to Wisconsin my wife would have had to hold the ECU on her lap since the wires are so long. Today I took it part way up Mt. Vernon Canyon and it runs good at road speed. I haven't driven enough to check the fuel milage, but it does seem to have a little better acceleration than with the carburator. Edd, when I started it with the EFI after it hadn't been run for about three weeks it started much the same as my Dodge Dakota pick up. Fired right up with just a little lifter rattle that disappeared very quickly. Normally, if I drive every couple of days I don't get any lifter rattle on start up. Every time I start it now the engine revs to about 1400 and then goes down to 800. Yes, I am finding the EFI enjoyable but I wish it would return to idle instantly like it did with the carburator. Edd, I really like your car.
Looking forward to NC next year.

A. Wulf

This thread was discussed between 28/06/2008 and 07/08/2008

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