DDK - Die Deutschen Klassiker

My car is currently running with the stock fuel pump with a glass filter fitted before it enters the pump.

Prior to sending my carbs off to get rebuilt i noticed that whenever i had been out for a run, the fuel in my filter would have a stream of small bubbles running from the pump side back towards the tank.
This would quite often result in my filter emptying of all fuel after a being stood a while.

My first thoughts were that i had an air leak on one of the fuel pipes and so replaced all of the pipes - still the same thing happened.

A previous owner had fitted a facet electric pump before the manual pump (though still feeding through the manual pump)

When i had the car serviced at Strasse, they disconnected the electric pump and fed the fuel straight into the manual pump as they thought the facet pump might not be feeding properly.

It was only after this i noticed my filter was emptying.

1. Am i correct in thinking that the manual pump has a non return valve in it - hence if this has failed, could this be the cause of my backflow?

2. Is it best when using an electric pump, to totally bypass the manual pump and feed directly into the carbs fuel line?

3. If so, should i remove the manual pump and fit a blanking plate or is it alright to leave in situ?

4. If i decide to stick with the original set up - do the fuel pump repair kits have the necessary parts to fix this problem?

I would like to sort this for when i get my carbs back.

Any help appreciated

Now this is something i can help you with

My 912 had same prob the non return in the pump had gone would let fuel stay up it keep running back!!

No it dont come as part of rebuild kit!!! £50 and didnt cure my prob
I ended up fitting an early top part of a bug fuel pump only difference is the fuel pipes tad smaller.Started second turn of the key

I found this out after taking the pump to pieces 4-5 times and what a mission to get the pump off
if you want to keep the og look go for the above or if its cost id go facet fuel pump.

I would keep the orginal pump and look to strip and clean it.

I wouldn't worry too much as my filter goes empty when I park up for a while and my car starts almost first turn every turn now.

Also could I point out the glass filter... if it was me I would lose that..... I just don't like the idea of glass in the engine bay. If that glass breaks the fuel is going to go every where... Stick to the plastic ones.. and go for a smaller one as well.. I only used a large one because I wanted to catch all the crud coming out the fuel tank after I cleaned it out.. Now it's got a smaller one..

So going back to the fuel pump I would wait till the carbs come back and then set them up..

But you could strip and clean the pump and have a look at the NRV in there.

Yep just what he said

thats why i kept the orginal pump
Only thing was that damn little black nrv in the top of the pump wouldnt draw up the fuel on mine or hold and sort of pressure either.I also fitted a filter beside the gearbox always good keeps the crap out of the carbs

Cheers lads

Got to say that it didn't seem to be causing any problems with running - just knew it wasn't right.

Maybe i will just leave it alone -

Memo to self:
if it ain't broke, keep your bloody fingers off - it will end up costing