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MG TD TF 1500 - Need Carb help

My 52 TD was running perfectly and suddenly won't run at all. Car starts and then quickly starves for fuel and dies. Checked fuel pump and float valves ok. Is there anything else to check before disassembling the carbs for further inspection. I notice that the piston in one carb has more resistance to rising than the other one. I have the same 30 weight oil in both and neither is binding. any help will be appreciated. Paul.
P.W. Lester

I had a similar symptom in the past. I rebuilt the both entire carbs, installed new fuel pump, wires, plugs, etc. Still wouldn't run. I then loosened the distributor (first time there), turned it about 1/8" to the left, and it ran like a kitten and still does!!!
Ed
efh Haskell

If you are sure that it is being starved from fuel, then the first thing to check are all the fuel filters. The tank, the pump and both carb filters.

John
J Scragg

95% of carburetor problems are electrical in nature.

The truest statement ever said. More people tear SUs apart when the issue is electrical.

What leads you to believe it is starved for fuel and not lacking spark?

Peter
P G Gilvarry

EFH Haskell. I tried turning the Distributor a slight bit to the left. Sorry to say it did not help but thanks for replying. J. Scragg, pumped a quart of gas into a jar with the fuel pump to check for separation of liquid but found none. Pump works fine. removed filters from float bowls and checked that float valves were not stuck. Lifted pistons and held the float plungers down with key on and fuel came up through the jets as it should.
P.W. Lester

Peter, I checked for spark at the plugs. I have a good blue spark. I checked the condenser and it read .22mf. Points are new and are set properly with a blue spark when engine turns. I have the recommended red dist. rotor. I am at wits end today. May just have to leave it for a while and go back fresh.
P.W. Lester

With ignition on press on “tickler” on top of carb bowls, pump should tick and fuel come out of overflow pipe if filters are clean.

Test each carb in turn.

Peter
P G Gilvarry

Peter, I have done that and and also removed the filters and checked them and the float seats for good measure. I used the gas I drained when checking the fuel pump operation to mow my lawn this morning and the mower ran fine so gas is probably not contaminated either.
P.W. Lester

Turning the distributor advances/retards the spark (depending upon direction).

Do you by any chance have an in-line fuel filter anywhere between the gas tank and the pump?

Lastly, check the gasket between the head and the intake manifold, you may have a vacuum leak there which is causing the issue.

Good luck and let us know the outcome.
Charles Duffy

As I remember I loosened the dizzy, turned the engine on and turned it left and right until it ran smoother. You must have the engine running to do it this way.
efh Haskell


I don't see any mention of the choke.
J Barry

It starts so choke might be OK.

I would put a spark tester in the #1 plug lead and watch it as it dies.

Peter
P G Gilvarry

I had an issue with bad idle, unable to accelerate the engine and occasionally dying.

Spark tester showed diminished spark, swapped the condenser, idle was 200rpm higher and problem was gone.

95% of SU issues are electrical in nature.
P G Gilvarry

Both AM coils and condensers are suspect. If you're happy that the condenser is OK then swap the coil with a proven functioning unit. Fault finding by replacing one suspect component at a time with a known serviceable item is a foolproof method. I also think that the problem is electrical, and if I had to take a punt my bet is it may well be the coil, even though it does initially appear to provide a good spark. Cheers
Peter TD 5801
P Hehir

I did notice with the bad condensor the coil was hotter than I would have expected, runs a little cooler now.

Peter
P G Gilvarry

Took off Saturday and did not work on the car. Today I decided to use a kind of shotgun approach. I reset the valves, reset the timing both per John Twist videos. Cleaned and gapped the plugs and reset the jets on the carbs. Engine starts and runs fine. Was the problem electrical? Almost certainly but I may never really know. If the problem re-occurs I may change the coil as it has not been changed since I have owned the car. Many thanks to all who took the time to offer help and advice. This forum is invaluable for those of us who have to keep these cars running ourselves.
P.W. Lester

Job done! Congrats...enjoy the drive!
Charles Duffy

The issue with a shotgun approach, did you fix it, or is an intermittent issue that fixed itself, temporarily.

This is something that happened suddenly, so not valve adjustment. Carb jets unlikely to have changed suddenly.

Plugs maybe, but it was running, then not running well.

Timing might have changed, was distributor loose?

Drive it like you stole it, time will tell.
P G Gilvarry

Peter, intermittent is certainly a possibility. Distributor was not loose. Plugs were sooty. and points were a bit too close but not not enough to cause it not to run. Time will indeed tell. I just hope it is not too far from home.:-)
P.W. Lester

Glad it’s now running well. The problem with the shotgun approach is you really didn’t learn anything other than tossing a bunch of parts unnecessary parts into the mix has cured your issue. You still don’t know the root cause. If the problem occurs again at some point down the road you’ll be left wondering and with no better knowledge of where to focus your attention. Was it a bad plug, condenser, bad high tension lead, weak coil, carbon tracked distributor cap, simple carb adjustment/ necessary rebuild, dirty/clogged filter etc. Though a bit time consuming it is always a good idea to make singular changes at one time. If the change didn’t fix the problem then undo what was just done and try something else. Repeat the process with making adjustments to the next possible item. Rarely will it be a multi system failure of components or adjustments.

At any rate, now that the engine is running well again, it’s now time to enjoy the fruits of your labor.

Bill Chasser
TD-4834
W A Chasser

Paul, My next door neighbor has a 51 TD. He had a similar issue as did I with my MG-B. It turned out to be the nuts that hold the intake/exhaust manifolds loosened to the point causing a vacuum leak. Tightened the bolts and problem solved. Try it out, nothing to lose

Cheers

Gary
79 MGB
gary hansen

Gary Hanson, the car is still running ok but just for good measure I tried the manifold bolts and got a little better than half a turn on each. If not part of the problem it certainly would have been in the future. Thanks, Paul.
P.W. Lester

This thread was discussed between 05/07/2019 and 15/07/2019

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