MGB: Help Car wont run right HELP

My MG is no longer running right. It has been a while now, when the engine starts it idles fine, but when I begin driving, it lurches, and feels like I am pulling my foot off the gas, when I am not. I have a Weber DGV carb, that was just rebuilt in hopes of fixing the problem. It did not work, and now I have nothing else I know to do. A friend of mine says it sounds like it is losing compression. What are any thoughts that you may have? Should I just take to a mechanic? Thanks
Josh

First of all you need to update your information, we have no idea on what year your car is.
Does it have points or electronic ignition?
Has the compression been checked?
Have the valves been adjusted recently?
Have you checked the timing?
Most running problems are in the ignition system and until everything in it has been checked and set properly you can't even think about the carburetor.
If the distributor has points in it they may be closing up and that will retard the timing.
A tight valve will also lower the compression.
Old distributors also may have weak mechanical advance springs and so the advance curve will be screwed up.
Is the vacuum advance mechanism operating properly.
These things are easy to check and your problem probably lies somewhere in the things I have mentioned.

Thank you Daniel, I was about to say the same thing. I am not much of a Guru or anything like it but one thing I learned is that you always have to check the simple things before you jump into the big things.

This cars work on a very simple concept: Gas, air and Electricity.

If your gages work and you get nice/normal oil pressure, chances are that the problem is not on the engine itself. Mechanical should be out.

Since you had the carb. rebuilt, perhaps you can look into the fuel pump. If you have the kind with points, perhaps they need to be cleaned. If you have an electronic pump, it may need replacement. If none of these are the cause, then you can check the electric portion of the ecuation.

Distributor - Points or no points - clean or not?
Distributor Cap - good condition or cracked?
Rotor - check the tip to make sure that is not worn out and it's making contact.
Wires - when was the last time you changed the wires? perhaps one of them is cut or not transfering energy completely. Check them one by one.
Spark Plugs - When did you changed them last?
Coil - Even though this coils are ment to last forever, forever is just a figure of speach, they do go wrong, even if you car is an 80, that makes your coil 28 years old... MMMmmm...

I personally was getting some weird things happening to my car and it was the distributor, so I changed the distributor and the coil and now it's riding like a dream.


I hope that helps...

sounds like a fuel delivery problem, could be a little foil part from a fuel additive bottle in the tank ? seen it a few times, or a dirty or faulty fuel pump

Take a look at all the hoses that connect for vacuum, especially the small one that controls the advance on the distributor. It could be the fuel filter too.

Hmmm.

I had a similar problem in my GT when I first purchased it. It turned out to be a fuel pump issue. You might easily check that your fuel pump is delivering the goods (gas) at the right rate.

The car is an early 64, It has a recently rebuilt engine, yesterday I rebuilt the carb, less than 3 months ago replaced the coil, and had a new rebuilt distributer put on it. I changed both fuel filters, and put new fuel pump on about a month ago. Tires are new, spark plugs are new, all wires look good, all vacuum lines seem to be working as they should. Ill check everything else that was listed this afternoon. Hopefully I can find something.

It idles great, it is just when driving, it feels as though it is flooding out, rpm's cut way back for a second, then rev up again, then cut out and rev up all without the gas pedal moving.

It sounds like the float level may be set wrong in your carb. Webers are VERY finicky about float height. If its not within 1/64" (height and drop measurements) it won't run the way it should!

It sounds like the float height may be set wrong. The float height and drop level need to be set within 1/64" of specs for it to run correctly, or it will flood and run out of fuel at odd times and respond as you describe. I think the specs are even listed here in the library. Be cautious on where you measure from. Some times the listing is with or without a gasket in place, sometimes its from a float seam or flat spot or notch on the float. There seem to be variations almost every year on the Weber design!

That would sound like the Weber downdraught hesitation symptoms. I am by no means a Weber afficionado, but I do believe that there are some articles in the Library here concerning that.

rudy Wrote: