MG Car Repair/carburetor and gas feed
Hi, I have a USA version 75 Midget. T1500 engine and a 150 CD4T carburetor. Having a problem with the carburetor and gas feed. I have rebuilt the carb and am trying to get the mixture correct. It runs real rich and lopes at idle. I have purchased an S353 tool and when it comes to time to turn it to change the mixture it is real difficult to turn. I am unsure how much force to put on the hex tool without damaging something. I that normal and it is really tight or do I have to loosen some set screw to allow it to turn?
The gas feed seems to allow only the top two gallons from the tank to feed. I have a new tank and new gas feed line to the carb and a new mechanical fuel pump. I added a fuel filter just before the carb and that allows me to see that the fuel is absent when the engine stalls. Working on the idea that there is a vacuum in the tank I pulled the lines off the separation tank and blew compressed air through the lines and all is clear, including the separation tank. I even ran the car in the garage with the tank filler cap off to no avail. As it stands I have to carry a 2 gal. gas can in the trunk to refill every time it stalls. Any ideas?
I have several thoughts on your problem:
1) If you cannot turn the mixture adjuster then it is probably at the end of its adjustment. My guess is that it has been adjusted too rich, so it needs to be leaned off by turning the wrench anti-clockwise. However, there might be a problem with your anti-smog equipment making the car run rich, so you might find that the wrench is at the fully weak limit.
Adjusting a Stromberg is not a simple matter. The best article I have seen was written by John Twist of University Motors. Here is a link to it:
2) I would check which fuel cap is fitted to your gas tank It could be the wrong one, depending upon whether your car was built to Californian specification or not. See the Moss catalogue, item #7:
3) The next time the car stops, go to the rear of the car and LISTEN CAREFULLY while you remove the gas cap. If you can hear a sucking sound, then the tank is not vented correctly.
4) I note that you ran the car without a gas cap. Did it stop? If so, then I would diagnose a strange problem INSIDE the gas tank. I did find such a problem on an old MG TC. It had leaves in the tank from an oak tree. The leaf would settle on the exit hole and block the fuel line. I have also seen an MGB with a faulty fuel pickup pipe INSIDE the fuel tank. The pipe was bent incorrectly so it would only suck from the top of the tank.