Datsun Roadster Forum-311s.org

Hi all,

More fun today. One SU peeing out the overflow all of a sudden.

Pulled bowl top, everything ultra clean and brand new. Float is plastic type sitting on top of the gas in the bowl. Tiny piece of hard resin-y stuff in the float needle tube, figured that might be blocking it up. Confirmed needle is sealing by blowing on it upside down. Spring is there, hinge is moving freely.

Tried a start up again and after 15~ it started shooting out again.

Also, my other carb seems to be seeping slightly out the 'nozzle' on the bottom of the carb or perhaps above it and flowing down. I am not sure how that seals up as the nut above is the idle adjust correct?

What fuel pump are you running? Stock or electric? Check the pressure, is it possible it is just over driving?

The tiniest fragment between the seat & pintel will cause it rubber , rust , calsium

notoptoy wrote: Mon Aug 16, 2021 7:44 am What fuel pump are you running? Stock or electric? Check the pressure, is it possible it is just over driving?

Just stock.

Then yes, probably just some grit dust or dirt working it's way through the system. Is there a filter after the pump and before the carbs? Changed the filter recently?

It has the stock glass bowl filter which is new.



found more crap blocking the needle again. Given it has happened twice in repeat succession I wonder WTF is going thru my fuel system and getting past the filter.

I am thinking of adding a second filter where the soft line drops down to the fuel pump.

It gets crusty at the carb nipple, ( alum meats steel) plus lots of debri e after the filter
And you can get electrolysis between the brass and alum that pits the needle / seat

redroadster wrote: Mon Aug 16, 2021 1:09 pm It gets crusty at the carb nipple, ( alum meats steel) plus lots of debri e after the filter
And you can get electrolysis between the brass and alum that pits the needle / seat

it is almost like a shellac or something. thin hard and plasticy. everything in the carbs is super clean.

Datsun used musalac , that old glue on vacuum hose lines maybe fuel too

Never hurts to filter fuel. Have you checked or cleaned the screens in the fuel fittings at the float bowl? Blow compressed air through your fuel lines from the filter to the carbs, maybe with a clean cloth over the ends to see what comes out. My favorite varnish cleaner is Berryman's carb cleaner, but it will damage some paints just like any of them will so be careful to wipe it up.

Welcome to old car teething exercises! It's testing you to make sure you're committed

All dry after removing the second chunk of schmutz. I will probably install an extra filter as a safety measure.

cbez wrote: Tue Aug 17, 2021 1:47 am All dry after removing the second chunk of schmutz. I will probably install an extra filter as a safety measure.

I ran a nice inline, perforated metal mesh filter when I had carbs as a second to the one before my electric fuel pump. You can see it here in the pic I posted when I sold these items... the black metal cylinder. Worked great and was easy to install with a very small footprint. It unscrews if it needs to be cleaned (mine never did).