From: Bruce White - [email protected]
Date: 28/05/00
Time: 22:18:01
Remote Name: 129.96.230.236
Hi Melvin, It seems you may not have isolated the problem well enough.... Assuming the fuel system did work at some stage in the past and after your recent rebuild of the SU pump you have the same fuel problem then I would look elsewhere first. Do you have inline fuel filters before and after the pump?? If so, have you actually seen that there is no fuel in the filter on the outlet side of the pump when your problem occurs? Does the pump still run (tic,tic)?? Is there fuel in the filter on the inlet side of the pump??? If you do not have a filter on the inlet side of the pump, I think it would be a good move to add one and keep an eye on it changing it yearly. These old tanks are hard to clean 100%, I am amazed with my relatively clean tank at how much dirt the inlet filter still picks up. If you do isolate the problem to the pump, another option is a new 6v universal pump. Once again these MUST be located at the back near the tank and attention should be given to the height of the pump relative to the tank - instructions are included showing you how to do this. To my knowledge, all these new pumps are designed only to push fuel not suck fuel - hence there position is important. These units can have one problem if you are using a single SU carby - the pressure delivered from these newer pumps is about 8psi and the pressure from your old SU is well under 2psi. We have found on our hotter summer days (30-40 degrees) that this can cause a problem. The small needle and seat on the SU carby (even using the newer style needle and seat) can not handle the higher pressure when you turn the engine off after a run. It seems the pressure seems to increase in the line between the pump outlet and the carby even greater then 8psi in these hot conditions. This results in the flooding of fuel from the top of the SU. Not a happy seen. I am unsure if this would be a problem with your standard carby? With an SU, this can be solved by adding an inline pressure regulator. Most of these have a simple dial setting that allows you to select a desired outlet pressure. I have found 1.5 psi works well. A cheaper solution is a neat little inline fuel filter that has a pressure relief system built in itself. I have used one of these in a Morris 8/40 special years ago and it also worked well. The 6v pump is about $80 to $95 Australian, I can't remember what the pressure regulator was worth but it was not cheap either. These prices make the continued use of your current SU very attractive!
Good Luck
Bruce