MG-Cars.net

Welcome to our resource for MG 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 TD TF 1500 - Mobius acting up again

Went for a drive with a local club yesterday. About an hour drive to get there and the car was fine. While on the drive with the group I noticed a hesitation when accelerating in the low gears. It would sputter and loose power. It got worse as the day progressed. Usually when I eased up on the accelerator it would "catch" and then react normally. As the day progressed it seemed to happen in all gears. Switching between fuel pumps had no effect.
Stats:
pertronix ignition
New coil
New supercharger with carb from Moss
Two fuel pumps in series, switchable so only one runs at a time.
New in line fuel filter
In tank filter replaced about a year ago.
Previous test of generator showed good voltage at all speeds measured at generator.

Pulled each spark plug lead while idling and had spark at each cylinder. Pulling 3 and 4 had less effect on idle than 1 and 2.
I opened the float bowl and estimated the gap at the forks to be over a half inch. Adjusted to approximately 3/8. Had no effect on performance.

It's pretty scary when you are in traffic and keep loosing power. Had to pull to the shoulder several times until it "caught".

All ideas most welcome.

TIA,
Mort
Mort Resnicoff (50 TD-Mobius)

Vacuum leak?
Failing coil or pertronics?
I'd look for something loose (vacuum leak) then the coil and the pertronics next.
-David
D. Sander

Check the float bowl inlet screen for debris, also the screen under the fuel pump.

Is the inline filter BEFORE the pump? It shouldn't be.
Dave Braun

mort, if the car drove fine previously, why would you reset the float level?
in regards to david's post..with a super charger won't the troubleshooting items will be a bit different than with a normally aspirated induction system?

regards, tom
tom peterson

What was the ambient temperature? On a hot day, the engine compartment can become hot enough to start getting vapor lock, particularly if driving slowly. Cheers - Dave

PS. I agree with Dave B. an inline between the tank and the fuel pump should be avoided (although I doubt that it would cause the symptoms you are experiencing). See the article, SU Fuel Pumps, Facts and Myths in the SU Fuel Pump Articles section of my Homepage at: http://homepages.donobi.net/sufuelpumps/
David DuBois

Mort, is that the 'old' Pertronix with the magnetic sleeve? If so, you might want to take a look at http://www.ttalk.info/Failure.htm. Bud
Bud Krueger

Thank you all for the comments.
I shall check the front fuel filters and the innards of the distributor.
News at 11.

Mort
Mort Resnicoff (50 TD-Mobius)

Since the firing order is 1-3-4-2, especially check for gunk/short between those segments in the cap. Bud right on about the too tall Petronix magnets, I had to trim my rotor. If there is only one carb w/ the supercharger, use some carb cleaner spray to check for a manifold gasket leak on those cylinders. Didn't you have some issue earlier with the new setup? I forgot what that turned out to be? George
George Butz

Dave Braun, Minnesota, USA

Check the float bowl inlet screen for debris, also the screen under the fuel pump.

Is the inline filter BEFORE the pump? It shouldn't be.


Dave,
I checked the inlet screen at the banjo and it is clean. Where is the "screen under the fuel pump"?

When I first got the car I put an in line filter just outside the tank. I had no information as to the condition of the inside of the tank and was concerned about debris. Later on I learned of the in tank filter and replaced it with a new one.
Mort Resnicoff (50 TD-Mobius)

David DuBois, Washington state, USA View vehicle profile

What was the ambient temperature? On a hot day, the engine compartment can become hot enough to start getting vapor lock, particularly if driving slowly. Cheers - Dave



It was in the mid 60's, overcast and occasional drizzle. I watched the temp gauge and it was never over 80 C.
Mort Resnicoff (50 TD-Mobius)

Bud,
I read that article when I first put the Petronix in about a year or so ago. I cut down the rotor cap as you suggested.
The cap looks clean and with no signs of wear, carbon build up or any arcing. The carbon brush is springy with very little wear on the tip.
Mort Resnicoff (50 TD-Mobius)

Try it with points. I don't really trust Pertronix, as it fails w/o notice. Some users are happy until it stops working...

Tom Lange
MGT Repair
t lange

Next job for this week is to put the points back in and test drive.

Mort Resnicoff (50 TD-Mobius)

This thread was discussed between 19/05/2013 and 20/05/2013

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.