QuestionQUESTION: Hi Howard, the fuel pump in my '76 B (with ELC) is unable to pump fuel from the tank. It can pump fluid from an open container, and I can manually (orally) siphon fuel from the tank, with difficulty, but the pump can't seem to pull hard enough to get fuel from the tank. How can I determine whether I have a weak pump or a problem in the tank?
Thanks,
Billy
ANSWER: Hi Billy,
Clarify what you mean "With Difficulty" when you say you can siphon fuel from the tank. If you can start fuel flowing from the tank and lower that line down below the the tank, the fuel should continue to run freely from that line. Are you siphoning fuel from the line from the tank to the fuel pump? If fuel does not run freely when you lower the line below the level of the fuel in the tank once you start it flowing then the line is restricted by something. Remove the gas cap and use compressed air to blow into the tank line to clear any obstruction then siphon it again to see if it will flow freely then. Also check to see that the vent line from the tank to the charcoal canister is free and that the canister is clear.
I have only been working on MGBs from 1963 to 1980 and I never heard of "ELC". What is a MGB with ELC?
let me know,
Howard
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QUESTION: Sorry, I was trying to be clever by acronymizing Evaporative Loss Control. Speaking of which, I recall one of the manuals I have saying not to pressurize past 1 PSI with the evaporative loss control canister connected. Is that OK?
ANSWER: They probably said that because the tank nor the vapor separator or hoses on the vapor system can handle more than 1 PSI. I know the gas tank can't. The charcoal canister is plastic and is in the system up under the hood and it can not handle much pressure at all, especially if it is partially stopped up.
Many times in the dealerships we had to drain fuel tanks (BLM in their infinite lack of wisdom removed the tank drain plug) So now we had to siphon the fuel out. A good way to burn a pump up was to let the pump do the work, so the next was to siphon the fuel out by removing a fuel line and lowering into a can. If the fuel did not run mechanics would put a rag around a air nozzle on a air hose and blow a little air into the tank. This was not a good control so much more than 1 PSI was exerted at times. (this pressure was transmitted all the way to the front charcoal canister. I have seen mechanics who were not careful make the fuel tank bulge. I had a method that worked well. I would put the air nozzle of the air hose into the open tank filler and blow air in with no rag. This only slightly raised the air pressure in tank and I could raise the pressure enough to start the fuel flowing from a lowered fuel line by just lightly applying a rag over the open filler neck and thus it gave me a good control of pressure.
If we had a car with no fuel flow at the carb we did the following.
To test the flow of fuel to a pump the fuel must flow freely from the tank and the way to test this was to lower the fuel line below the fuel level and siphon fuel. Then we connected the pump up and opened a line on the output side of the pump and turned the pump on. If that was ok we went to the front and tested the fuel line there. If there was no fuel up front then it had to be a stopped up or a pinched line.
Howard
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QUESTION: Well, I've established the problem is a blockage coming out of the fuel tank, and I've been unable to clear it, though I put more pressure on it than was probably healthy for the tank. Is there a tool available for snaking the line out? Or should I use a chemical?
AnswerSometimes you can use an old speedometer cable in a drill motor to clean out lines. However, there may be something in the fuel tank too. In a dealership we have had to have tanks cleaned out. Some radiator shops do it. You can inspect a part of the tank by removing the sending unit on the right side and use a flash light to inspect part of it.
Howard
