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MG MGB Technical - nearly stalling when accelerating

hi,

I am back again on this forum with another MGB GT and not anymore on guernsey!!
right the problem I have with this new GT that I only got last sunday is that when starting the engine and trying to accelerate it firmly just to warm it up a bit, the power drops ... and when taking off my foot from the pedal the power surges again, this is with the choke on and a weird thing is that the fuel pump doesn't stop ticking when on ....

any ideas? fuel starvation? fuel pump? pipe blocking? float chamber?

thanks a lot
so good to be back again here!!
Alexia
Alexia

Hi, and welcome back.

Is it ok when it has warmed up ?.
Is there fuel coming from the carb overflows ?.
Does it have a standard fuel pump ?.

Assuming that the engine has been serviced (if not, do this first) I would start by checking that the carb pistons are not sticking (remove the air filters to get at them, only takes a few minutes).

Don
Don

Hi Alexia
My car has an electronic fuel pump fitted (rather than points) and this means that it constantly clicks compared to the original type. It sounds like there is possibly a mixture issue - will it start with the choke pushed in? If not, then start the car, push the choke in and then give it some gas and see what happens. It could just be set to run very rich at the moment and needs tuning.
Martin Port

Do you mean the power drops, or the revs?

Curtis Walker

Alexia. Nice to see your name again. Always good to have a former owner return with another car.

I agree with the others that there is not enough information for us to narrow down what the causes might be.

The first thing to do is to start the car, run it up as you have been, and write down what you are doing and what happens as you do various things. Do a little "playing with" things--turn on the headlights and see if anything changes, pull out the choke a little more or push it in a little. Martin's thought about trying to start the car, from cold and without the choke, is a good idea.

After you have noted what has happened and described it so the rest of us can understand what you are seeing and feeling, time for a tune up. Change the oil and filter (always a good thing to do on a new car unless you know when the oil was last changed and what oil was used). Set the valve clearances. Check out the distributor, inspect the rotor, distributor cap, wires and spark plugs. Check for loose wiring connectors, loose connections on the cap and plugs, loose bolts on the intake/exhaust manifolds, etc.--a general inspection and tightening of things.

Then, start the car, see what, if anything has changed, and let us know what you find.

Again, welcome back.

Les
Les Bengtson

If it has SU carbs you could check it has oil in the dashpots when you do the sort of simple checks Les suggested.

Have a look at what the fuel pump looks like. As other have said the little square modern types do click all the time.

Simon
Simon Jansen

I agree, check the oil in the dashpots.

j
JohnB

I have experenced this sort of problem with other cars I've owned. It oftern happenes when your spark plugs are old. If you haven't changed them in a while then do that and let us know.
Matt

thanks guys as usual much support is coming very quickly!!
have added a bit of oil in the dashpots but they were fairly ok, had time to let it warm up much more and irt was better... i really think this car needs a good tune up of the carbs as it slightly backfires a bit

process was:
try to start it cold without the choke: impossible so started it with the choke on, if choke decreasing car was starting to struggle so was putting back the choke
the car is a 72 model, high mileage: 94 400miles, engine never reconditioned so I'll have to change few parts before trying to get the MOT....
I'll try to change the oil, I'll change the spark plugs and leads, rocker cover, air filters and thermostat and then I'll see how it goes ..
thanks and have fun on the roads, winter is behind now!!
Alexia

This thread was discussed between 06/04/2006 and 10/04/2006

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