MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

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 Midget and Sprite Technical - Fuel Starvation uphill

Experienced fuel starvation going uphill a couple months ago. Was advised that dip tube inside tank may be old and sucking air and to keep tank full to get home. This worked. Bought and installed new tank from Moss Motors. Have installed new mechanical fuel pump (after testing on bench) it seems to work fine. Replaced fuel filter b/w pump and carb. Ensured 1/4 rubber is on 1/4 tubing and 5/16 rubber is on 5/16 tubing and all conections tight. What's left to check? It runs fine on the level. Thanks, Rush
RP Pond

Hi Rush.

What car is it? If it has a mechanical pump, it’s either an early 948cc or a 1500. Also what carburation?
Dave O'Neill 2

Hi Rush,

Fuel starvation or fuel evaporation ?

Was it a hot day ?
Malc Gilliver

Many moons ago my Frogeye gave symptoms of fuel starvation when going only around left hand bends. I could not fathom it nor could pros.
On the IOW it developed a further problem up the hills.
Eventually gave up and called a breakdown provider. He had recently had a car with a similar fault……the coil. I was using an oil filled coil of some age and, apparently, when cornering / climbing the oil level changed and some sort of fault occurred. Worth a try?
Alan Anstead

Alan I ought to have remembered that. I had the same problem twice, both times on MkIII 'Tina's.
The factory fitted the coils just inboard of the grille where they got soaked and they were fitted "upside down" into the bargain, so they had leaked.
What clown thought that was a good idea?
Standard fix was to relocate the coil to the left inner wing and turn it right side up.
Both times I refilled the coil case with transformer oil but I needn't have bothered with the expense. It's essentially coconut oil which is cheap and easy to get from the supermarket. It works fine.
Greybeard

Thought i was the only one that had wobbly coil issues-
I had a 2.0Litre mk11 Escort that i used for club track days and had trouble with it missfiring/ cutting out on hard rh turns, felt 100% like fuel starvation---nearly did my head in trying to fix it but same thing --bl%%dy coil --didn't like going round rh corners
William Revit

Hmmm. I wonder if there's a way to check if your coil still has oil in it.

My Sprite coil's tilted down at the sharp end. And it is very probably/possibly from the 60's , as I've never changed it. I've got a spare of the same vintage.

Never noticed any oil leaking out though. You would I assume. Or maybe I just didn't pay attention. Maybe I should buy a new coil. lol.

anamnesis

I was once told it was a known thing amongst racers and they always mount then vertically because of this, yet back in the day many manufacturers mounted them at all sorts of angles with no apparent problems.

Trev
T Mason

Maybe mine aren't oil filled anyway. Not all 'older' coils were oil filled. Some used asphalt. Could well be why mine haven't leaked.


"Traditionally, ignition coils were made with varnish and paper insulated high-voltage windings, inserted into a drawn-steel can and filled with oil or asphalt for insulation and moisture protection."

https://blog.simonbbc.com/products-from-powerspark/powerspark-ignition-coil/



anamnesis

AFAIK all Spridgets and MGBs had their coils pointing downward.
Dave O'Neill 2

Twice now I've had isolated incidents where the Frogeye has started misfiring and lost power going up an incline with a low tank. First time it cleared after a rest, second time it wouldn't clear even with another gallon but would just about run very roughly to get home. Hasn't happened since after hundreds of miles so still not diagnosed.
Bill B

I once had fuel starvation problems on my 1500, butonly on hills. Turned out to be a split in the pump diaphragm and although it was ok at lower fuel demand rates, it couldnt keep up on hills.

Did I read that you have replaced the pump? If its mechanical, did you get the correct length lever arm, plus the correct spacers?
GuyW

My pump was new Guy (mechanical as my 12V 1275 has a cutout) - shouldn't be that. I guess fuel evaporation is a possibility but there are mixed views on that. I also have a see through fuel filter just before the carbs so you can readily check for fuel.
Bill B

Check float chambers and carb jets for FOD? I had this on a Fiat once, very intermittent problem so I didn't figure it out until after I scrapped the vehicle for other reasons.

Root cause then was plating from floats coming away and would very occasionanally block the jet inlet (Weber downdraft). Great thing was that if you switched it off for a few minutes the FOD would float away and car would then be fine, so whatever you did when it conked out "fixed" it, many blind alleys explored with that one.
AdrianR

FOD?
anamnesis

rubbish - an
foreign object/debris
but Adrians mention of a Weber did remind me of something---float drop adjustment
Depending on what model SU's we've got here ,some of the swinging/lever type float arms have an adjustable/bendable drop stop which if the drop is insuficient can cause fuel starvation under load---quite common with dd Webers as well.
Doesn't matter anyway, looks like RP isn't coming back to report.
William Revit

Ah yeah. Sediment and crap. Thanks Willy, fod had me stumped. Lol.

Yep I've had bits move about and do that.

And good point, where's RP? Just noticed, he's the only one who hasn't posted since he started the thread. Hope he's not stuck by the side of the road trying to fix it. 😏.

anamnesis

I was wondering why we haven't heard from him. I was also wondering if the problem is present with the new tank, I seem to recall someone mentioning fitting a new tank and finding it was missing the pick-up tube, also if the problem exists on the level with a low fuel level. Is the connection into the tank the correct soldered cone, DAMHIK.
David Billington

This thread was discussed between 11/06/2025 and 14/06/2025

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now