QuestionQUESTION: I have a UK 1500 midget, 1979. It starts and runs well for around 10 miles under all load conditions. However, it then missfires for around 1/2 mile and then stops. Following this, it refuses to start for around 1 hr. Afterwards it missfires but I can get home. The next day it will be fine for another 10 miles and the process repeats. All filters are clean. I have been through the ignition system thoroughly and the fuel pump - one can never be 100% sure but I don't think these are not the problem. I suspect somewhere in the carbs, but where. Only other pointer is that the problem can I think be triggered if I drive up a (not steep) long hill - short steep hills no problem though. Any advice greatly appreciated. Thanks.
ANSWER: Hello: I would double check that the fuel supply to the carbs is good and consistent. Also double check that all fuel line filters are clean. There should be one inside the tank (a screen) which can become plugged. One way to check is to disconnect the fuel line at the carb and carefully put the end into a container, have someone turn on the ignition to where the fuel pump runs but the engine doesn't turn over. Check the flow it should be strong - if not suspect the pump or dirty fuel line/tank. You can try to use air pressure to blow air back through the fuel line to the tank. See if this improves things. If so, dirty tank.
If you have recently worked on, or had work done to the carb(s) I would check them after doing the above. However if not, they won't go out of adjustment suddenly so I would not think that is the problem or contributing to the problem. Hope this helps out.
Brian
---------- FOLLOW-UP ----------
QUESTION: Many thanks. The fuel filter is clean and the carbs have not been touched for a while. The smooth running before failure suggests the problem is heat related. I'll check the pump (carefully) as you suggest. The other thing I have noticed is that the heat shield is very grubby. I thought I might try wrapping the float bowls in silver foil and see if there's any change - I have heard a lot about vapour locks.
AnswerYes, it is possible that their is some heat related issue. How hot is the engine running after 10 min. of driving? Have you only noticed the problem in the summer temps? I have had heat related issues on a T series in the hot summer after stopping the car the bowls heat soak and it is difficult to start then runs rough until cool fuel from the tank takes over and the car gets moving. If you have good fuel supply try your foil experiment - if it works, viola, you've found your issue. Good luck.
