ADRIAN wrote:When fitting the pump, put the spacer on the pump with a gasket either side all smeared with thin coat of Hermitite or Hylomar sealant equivalent. Put the operating arm into the hole at the very top of the hole, and once the assembly is up against the block push the body of the pump downwards in order to line up the two bolts in their holes then tighten them up with spanner whilst holding the pump with the other hand to stop it moving. Can be a bit fiddly and difficult but it ensures the arm goes onto and stays on top of the cam where it is supposed to be, Fit petrol pipes onto the feed side of the pump only, then, with ignition wires disconnected at solenoid for safety, operate the starter. The pump should eventually pump up, squirt petrol out with force like a fountain, not a dribble . If it doesn't squirt, - the pump is faulty.
Another thought to check, If the pump you have is the incorrect type, in other words for another car, like for instance a Triumph Herald pump, the operating arm will be at the wrong angle. Only a slight difference in the angle of the arm will mean that it wont pump fuel, as the arm will be pushed more sideways by the camshaft lobe rather than lifted up as it should be on a Viva engine.
Thanks for the advice Adrian. I've been trying again to re-fit the new mechanical pump all afternoon, with no success. I primed the fuel line from the tank with one of those rubber pumps so I knew that fuel was in the feed pipe, before re-connecting to the fuel pump. I also looked inside at the camshaft using a mirror but nothing looked worn ( the camshaft didn't feel like it had a worn groove in it either when I stuck my finger inside).
Again when I was trying to position the pump I could hear the diaphragm moving as the activating arm pressed against the camshaft, but no fuel was coming through when I turned on the ignition.
However, reading your last message again, I see that you said to fit the heat insulator block to the pump and then fit the pump+insulator to the engine . My insulator looks fused to the engine block, so I would need to tap it off I suppose. Could this be the reason why my activating arm is not in the correct position, although I can't see how it would make any difference fitting the pump onto the engine+ insulator or fitting pump+ insulator to the engine, but I suppose normally when the cars were assembled then the insulator wouldn't be stuck to the engine block prior to the pump being fitted?