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S3 Lightweight fuel system problem


theredkite

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I've always had to manually pump the fuel pump on my Lightweight to get fuel to the engine to start it off. However after not driving it over the winter, no fuel was coming through at all, even into the glass reservoir under the fuel pump. Having taken the whole thing apart several times I can't find a blockage (even though I did have cruddy petrol in it last year).

 

My immediate question is this. When the fuel pump is off the engine, and connected to a fuel supply, should it draw fuel into the reservoir and then pump it out the other end? Any thoughts or suggestions much appreciated!

 

Mike

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Check the seive on the bottom of the lift pipe inside the tank(s) not clogged.

 

The cork seal inside the change over fuel tap could have dried out and be sucking air (common after standing) , check on eBay for Fergy tractor TVO change over tap (same - manuf. by Enots).

 

If the pump is a genuine AC or good copy , there should be a manual lever on the underside for you to prime with - if OK then you should get a good gusher at the carb end - they don't need much to start & run LoL

 

Beware of the non-genuine rubbish lift pumps..

Edited by ruxy
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Cheers Ruxy. I suspect the £13 replacement fuel pump I've used may well indeed be rubbish...

 

The lift pipe is clear, and so as far I can tell are all the pipes. It's all a bit of a mystery, but I'll try again when the new pump is fitted. Watch this space I guess...

 

Thanks for the suggestions,

 

Mike

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  • 1 month later...

if you take the lift pump off and strip it you should find two small 'penny' type valves...one traps the fuel as it comes 'in' from the tank...the other traps the fuel as it goes on 'up' the line towards your carbs (or injector pump on a diesel) and stops it running 'back' towards the lift pump....

These 'valves' are very simply 'lift' affairs and look just like 1 penny pieces....they are held in place by a retaining clip....take them out and make sure they don't have small piece of crud of some sorts under them preventing them from sitting down properly and doing their jobs because if they have become fowled ...instead of getting a good squirt up to the carbs the fuel will sort of go 'backwards and forwards' thru the pump without going on up to your carbs/injector pump.......and you can faff about all day and not have enough fuel up at the required place no matter how long you either crank the engine or work the manual lever..!

hope that helps!.:cheesy:

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Cheers Bob

In the end I replaced the pipe from the fuel tank to the pump, and for good measure the pump itself. When I tested it off the vehicle i.e. new pump and new pipe into a fuel can, the blooming thing still wouldn't pump, and I began to believe the laws of Landie physics had stopped working in this part of the country. Turned out the new pipe was blocked with crud - goes to show you can't be too careful.

I couldn't find anything other than replacement pumps around, but the quality really seemed to vary. I certainly think the first replacement I got was complete rubbish, but the one I finally used seems good stuff.

Thanks for all the help,

Mike

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It's probably worth sticking a little non-return valve inbetween the lift pump and the tank too..........I took the seat panel out and put one about 3" or so down the line from the tank.......then if you get any problems re-occuring with your lift pump at least the fuel can't drain back away from it causing an airlock...more important with a diesel than a petrol I guess but worth doing anyways.......:-)

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