Petrol pump mystery

[andrew_27]

Took my Toledo to a show on sunday at Beamish museum, lovely weather and a massive turnout... but the little Triumph decided to die once i arrived.
Turned out the float bowl was completely empty and the pump wasnt delivering, its the older type with the little primer handle underneath and pushing this made a bit of a wet squeaky sound from the pump and still wouldnt draw fuel in. so with a modest amount of spares available i decided to swap the diaphragm, it fired up after that and got home without any issues, However.... the diaphragm i took off the car looked fine so one home i swapped it back and the pump worked fine... i can only think perhaps a stuck valve (they are only a few months old as i renewed them) or some sort of bloakage. I wondered if anyone had any other ideas/suggestions? im just concerned that it has the potential to do it again.
cheers!

[tony g]

Did you removed the tank filler cap during your diagnosis? Maybe you had a vacuum forming which the pump wont like and after you released the pipes/ pump for inspection you allowed air back in hence no problem after that. If you run it again and it dies I would remove the cap and then re prime and see if it goes.

On my sprint I had similar issues and found the small slot in the cap had some small debris in there. I cleaned it out and enlarged the slot to allow more air to enter.


Tony

[andrew_27]

ah good call, i never thought of an air lock and it would make sense. I didnt take the cap off but if it happens again (fingers crossed it doesnt though) ill definitely give that a try.

[Jon Tilson]

Also have a look for perished sections of rubber joiner on the fuel line. These can develop pin holes
that let the pump suck air.

Jonners

[trackerjack]

Flakes of rust collect in the bottom of the tank and block the outlet. When the car is shaken or the draw is stopped they fall back.
Then when the car is started again they may or may not block again.

I have had all this happen over the years and even had a bit of crud in the float needle that caused fuel starvation or flooding as it liked.

Blocked cap air vent would be my prime guess though as suggested.

[andrew_27]

thanks for all the suggestions! I took it off the car yestrday and dismantled it, i also checked all hoses and connectors, everything seems to be fine and its back on the car running without any problems, also checked the float needle and thats working freely too. I have an in line filter before the pump which has collected a bit of muck but doesnt seem to restrict petrol flow at all. I plan just to continue running it and see if it occurs again and investigate from there (im not carrying a spare pump in the boot though )