Hello altogether,

I´m facing a problem with what I think must be the fuel supply / fuel line, however I´m not sure what to do - here´s the situation:

Whenever the car is parked for a longer amount of time (couple of weeks and longer), it seems that the fuel pipe between the tank and the pump is emptying, and the car won´t start the next time. The solution to that so far has been to fill up the pipe backwards (pouring fuel into the pipe from where the pump is as well as from where the carburator is). I have always assumed that the old, original pump might be worn out and simply too weak to pump the fuel all the way from the back when the pipe is empty. Once the car is running, it is running just fine, so my approach was to install an electrical fuel pump that is stronger than the old one.

Yesterday I installed an electrical pump, which is now bypassing the mechanical one. The pump is working fine and running as it should be. In a test before connecting the new pump to the tank, it was pumping gas from a jerrycan all the way up to the fuel filter and carburator, no problem, engine starting.

However, when connecting the fuel pipe (that is coming from the tank) to the new pump, I could see right away that the pipe was empty, no fuel dripping out. After connecting pipe and pump, there was no more fuel being pumped (I can see it as the filter is transparent) and the motor died as soon as the gas (which was already inside the filter) was up. The tank itself is still half full so, it can´t be that and the new pump is running at normal speed.

Bottom line now for me is: changing the pumps doesn´t solve my problem after the car being parked for a longer period of time.

Now I´m left guessing of what the problem could be:
- why is the fuel line constantly emptying when the car is parked longer?
- is the fuel line maybe clogged (is that even possible?)
- did I overlook some part in the process? As far as I know and researched, there is no other pump located inside the tank
- anything else I´m not thinking of?

Anyone have an idea of what it could be? What would you check or do next if you would encounter this situation?

Thanks in advance for your help, looking forward to your replies - every little hint helps!

Cheers

Timo


P.S.: This is a quick sketch of the old, new and test setups mentioned above:

 

Have you replaced the rubber hose from the tank to the metal line? It sounds like it might not be sealing and you get air in the line and lose your prime over time. Take it off and push some wire (or compressed air) through the open metal line to see if there is a blockage. Old fuel varnish or decayed rubber pieces could cause blockage. Not sure if yours has an in-tank strainer that could be clogged.

 

No, I haven´t - that´s probably gonna be the next step in the process.

Thank you for the hint, I´ll get back as soon as I have tried that out!

 

UPDATE

So it seems I found the solution:
There was a little crack in the fuel hose right after the tank. The hose is quite old and thus lost almost all of it´s flexibility. I cut the part with the crack and re-attached it and that solved the problem. I´ll probably replace the whole fuel line soon to tick that off the list.

Thanks everybody!