Fuel pump knocking/won't start

[Hitchinrides]

Hi all!

I recently bought a 1.9 1982 Kamper, it runs fine unless left sitting for a week or two - when the fuel pump knocks and it won't start. I know it was left unused for 2 2 years before I bought it. The pump had been replaced with an electrical one at some point. Can hear it knocking as the engine is turned on, but nothing else happens.
I took the intake pipe from the bottom of the pump and injected petrol from a pipette, and it worked fine, until being left to stand for two weeks.
No strong smell of petrol when parked.
I'm thinking the fuel line could be persished and fuel is slowly evaporating leaving a vacuum? Or maybe a faulty pump? Any thoughts would be appreciated.

Many thanks

Love the forum!

[bigherb]

If the pump is rattling then it has no fuel to pump. Where is the pump mounted?

[Hitchinrides]

On the right hand side, against the edge as you look into the engine bay


Sent from my iPhone using Tapatalk

[bigherb]

It is too high and too far away from the tank, the pumps are not designed to suck fuel any distance or height.
The pump should be mounted level and near the tank outlet like this.

[CovKid]

I have same set up and unfortunately ran out of petrol a couple of weeks ago. Unless the line is full of fuel between tank and pump, the pump will be unable to pull the fuel through. If there is fuel in tank, remove pipe where it connects to input of pump, then blow through it to ensure no debris is sitting against tank outlet then point hose down until fuel emerges. Quickly fit hose to pump again, then try starting. Line should prime all the way and it should start eventually.

On the plus side, that knocking sound (like a hammer drill) is a 30 second warning that you're going to break down

[Hitchinrides]

Thanks for replies. The original pump is in the engine bay next to carb so don't see why new one wouldn't work there?
I will try to re prime it today and then buy some pipe to replace it this week. Hopefully that will sort the problem.


Sent from my iPhone using Tapatalk

[bigherb]

Thanks for replies. The original pump is in the engine bay next to carb so don't see why new one wouldn't work there?

If you mean the original mechanical pump it is a different type, a suction pump.

[CovKid]

As Big Herb says, two different principles. Both have their advantages and disadvantages. Mech pumps really struggle if line goes dry, worse if float bowl is dry but in good fettle they're very reliable. Electric pumps also reliable but they hate a dry line between pump and tank. Electric one pushes so has to be close to tank. Mech pump sucks (in more ways than one)

[Hitchinrides]

That makes sense. Many thanks


Sent from my iPhone using Tapatalk