QuestionQUESTION: I have been having trouble with my 1973 MGB GT. It runs fine at start up and under a load until it decides to lose power. I have two fuel pumps I can switch incase one quits. It will restart after a few minutes but runs rough. I have replaced the coil and checked the fuel pressure, the distributor and 2 SUs are fresh rebuilds.
I think the engine isn't getting enough air and choking itself to the point where it dies.
any help would be appreciated.
ANSWER: Hi Adam. This is a tricky one. I really need to know which part of the USA you live in, and also what fuel you are using.
I ask because I have had a lot of reports of engines cutting out or refusing to restart, particularly in warmer climates like California. I am suspicious that it may be caused by the stuff they have started to add to the fuel. In particular, are you using E10 with 10% Ethanol?
Next, have you still got the original heat shield that goes between the carbs and the exhaust manifold, and is it still intact? This is essential. Without it the fuel will vapourize in the carbs or even in the fuel lines.
And finally, the problem could be carb icing. I am not joking. This can happen on a damp day with temperatures as high as 20C (68F).
Please get back to me.
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QUESTION: I should add its stock but without the pollution control
AnswerOK Adam. Sounds like carb icing to me. This has been happening more and more in recent months. The next time the engine starts to die, pull the choke control out. If the engine picks up again, that confirms it.
Once the engine has warmed up, it should not die any more. Basically, water vapour from the air is freezing in the SU jets and closing them. Pulling the choke cable lowers the jets and re-opens them.
You could try using a higher octane `super' gasoline. It contains less of the additives that are causing this problem.
As a longer term solution, you need to duct some WARM air into the air intake.
Sorry there is no easy answer to this problem. We are currently working on it.
