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MG Midget and Sprite Technical - Any Ideas?

Hi Everybody,

I thought I had it licked and I was going to get to enjoy driving my midget this summer. Since she was running Great just like a normal car. I decided to take a little trip down the interstate 65, 70 mph I got about 10 miles then I noticed the power start to drop. So I turned around and started home. Had to get off the interstate because it just Keep getting worse. I nursed her home at an average of 8 to 12 MPH.
she didn't have enough power to get out of 2nd gear and if the speed got up to 15+ MPH it started spitting and sputtering like the mixture was completly wrong or the timing changed a lot. The distubitor was still tight and I had driven it around before in the same set up as today with no problem. I had taken it out on the interstate, but for only 2 to 3 miles. Ok the set up I have is a 1275 with a Weber DGV. I did not have a chance to look into it today, but here are my thoughts as what might have happened. 1.The power valve in the Weber went bad only part not replaced in the rebuild. 2. The fuel line to feed the Weber runs to close to the Header / radatior and the gas is getting to hot causing issues. 3. The fuel regulator went bad and is actually starving the engine. If any body has had this problem before am I own the right track or is there a different direction I need to be looking?

Thanks in advance for your help.

james caddell

James

Id say your in the right N.hood, those are areas Id be looking at...Id add in the fuel pump and the fuel filters on the list also.

take the easist 1st and work up to the most difficult to check...no doulbt that will be the one at the end.


Where in north carolina? My brother is in Angeir, just out side raighlie

Prop
Prop

Did it run fine when cooled down?

A
Anthony Cutler

Coil, Points? Most common point of failure.
Graham
Graham P 1330 Frogeye

points closing up

often because they havent had a spot of oil added to the cam after fitting new ones

the nylon tip wears away with friction against the dizzy cam

later Lucas points sets (late Minis, Metros etc) actually have a grease impregnated felt pad fitted to lubricate the cam faces

Or condenser beginning to fail (OK everybody shoot me)

or coil

No matter what you think carburettors very rarely fail in service.

Electrics do
Bill sdgpm

Thanks for your Ideas A little more info. When It cooled down it still did not want to start so I just pushed it in the garage. I do not have points. I replaced them with an electronic ignition several years ago.
james caddell

Is your gas tank vent working? When I first got my Midget it would pull a vacume after running at high speed for 20 minn. I figured out what was going on when I took off the gas cap and there was a giant sucking sound as air rushed in.
Steve
S E Bryan

read a thing by David Vizard a long time ago..... same thing happening, and it was traced to a particular make of points which had a type of plastic which, when it became warm, also became soft, and the points didn't open the same as when set. Once they cooled down, the problem disappeared........... until they warmed up again!. it definitely sounds like points to me, and I had exactly the same problem with a Lotus Seven a long while ago. Also had a similar thing with an invisible crack in the distributor cap - I didn't see it, but once changed, the problem never came back. Worth checking......
D le Versha

but he hasnt any points, he's electronic...

Maybe coil breaking down under load but with points OUT of the equation fuel IS a possibility.
Bill sdgpm

Hey thanks for your Ideas. I am eager to get home to look at a few things the gas tank venting idea sounds like it could be the problem because the problem got worse kind of like getting the flue. You start filling bad and you fill your self getting sicker and sicker and I added a few gallons before I got on the interstate the most gas I have had in the tank with this carb.
Also I have not hard any thought on the gas line being run to close the header and raditor. With the Weber Down draft I do not have a heat shild and the fuel line was almost in contact with the upper raditor hose. Could the heat cause the fuel to vaporize before it reached the carb?

Thanks for your help.
james caddell

No points is not a reason to ignore the electronics which often can get flaky when warm. I happen to have a VW Passat, one of the last models with a distributor, and the hall sensors are known problem areas. Have had one go, they start to fail when hot by not restarting, if you're lucky they go again when cooled, until they don't anymore.

I've learned from experience don't not check something just because it's new or newish, on at least 2 occasions a difficult to find issues was a newish part that I discounted as "it can't be that it's new", live and learn.
David Billington

Ok It was not the Tank venting. Checked all filters all good. Still does not want to start. Took the carb apart to check for any obvious problems, dosen't seem to be any. Does any body of the top of their head know the symptioms of a bad coil?

Thanks
james caddell

http://home.mindspring.com/~purlawson/files/LucasPointsIgnitions.pdf
Trevor Jessie

James,

The symptoms of a bad coil are close enough to what you describe that I would be inclined to try one.

Charley
C R Huff

This thread was discussed between 01/06/2009 and 02/06/2009

MG Midget and Sprite Technical index

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