yeah deserves a medal turning the filter around 

*cough* EFI conversion *cough*

4 hours ago, dvderlm said:

So the AA man helped any captured crap on inlet side of old fuel filter to flow into the carb. 

You need to test the pump..

 

 

I wonder if the float is sat too low.

Certainly on Webers going up an incline causes more fuel to cover the emulsion tub holes as these are slightly offset to rear of the well by design with float hinge pivot facing direction of travel. (I once drove with a reverse mounted DMTR from Golf - fine in the flat fens of East Anglia).

 

A swirl pot needs a return or the pump will overcome the needle valve and flood, It's just a means of removing bubbles. A large accumulator after pump

(I use a motorsport fuel filter) might help.

 

 

 

 I can't for the life of me work out how to tell if that's the case/ if so how to adjust/replace the needle valve. The float seems to be pinned in, and the needle valve isn't obviously removable. Ruddies and Haynes weren't much help.

 

Fuel pump is spurting clean fuel nicely, Haynes didn't have a flow rate but 5secs of cranking have a few hundred mL. Seems okay. 

Looking through Etzold Polo "so wird's gemacht" it reckons stuttery running in cold weather, especially before reach full operating temp. (2 hours in these Siberian conditions)

is due to the part-load channel heater element having failed, in 1b3 on cars upto July1983 manufacture.

 

Test with cold engine and bulb connected from batt +ve to the heater element's spade connector. 

Dont confuse with autochoke bimetallic strip heated element (overcomes choke mech inertia).

 

 

Can't find torque for carb mount.

There's a sieve filter in original pumps - that can be removed and cleaned with petrol. If pump has slot screw on top, might be worth checking that filter (and billing AA).

Newer 

 

1b3 float should droop 28.5 (+ or - 1mm) with top held perpendicular to ground and float arm just pushing the needle.

Schwimmerjustierung... from Ruddies berlin

 

 

Fuel pressure spec is 0.2 to 0.25bar = 3.6psi

Float pin needs driving out with a punch. Normally one side has a split in the tower, and other side is solid.

Carb top must be warm, or risk splitting /breaking the metal.

 

if float height is wrong just bend the metal tang to float down lower fuel leaner,  up for higher fuel. richer.

Lotus set fuel float 1mm higher for none emissions zone cars.

Edited 28 February, 20188 yr by dvderlm

14 minutes ago, NebulaicToaster said:

. A large accumulator after pump

 

no, that was wrong. before pump!

The wind and snow just started blowing so I've retreated inside. Tried the pump again just now and it seems my battery has drained, very weird. Only getting 9v across it, wouldn't crank. Puzzled me a bit, could a dash of petrol on the starter short it?

 

15 minutes ago, dvderlm said:

 

if float height is wrong just bend the metal tang to float down for higher fuel, up for lower fuel. 

What do you mean by tang? Float is just held on by the pin then the springy thing with a flat circle holding the float up. Sorry for lack of technical wording. Compared to my old autochoke carb that's in pieces the float looked about the same level.

You've been very helpful, I owe you all a pint at the social!

 

It just seems peculiar that even if she cuts out on hills, why she wouldn't reliably start once back on the flat. I might chuck it in tomorrow and swap the manual choke onto a proper polo 1b3 from the scrappy and try that. I just want to diagnose the problem before replacing all sorts.

Hm, too long dealing with Webers. Been looking at the ruddies pictures of 1b carbs.... the metal bit that engages with the needle, that leads to the plastic float.

You should be able to bend it where it reaches float.

 

Measure it against another carb by all means. From gasket to float top I think while just pushing on needle.

 

 

cuts out on hills at very low throttle.

It's looking like part load enrichment which goes through the idle circuit. See the bubbly flow...

 

Valve 13 is opened by vacuum letting fuel from well flow up past the enrichment jet 48 and then through idle circuit.

It has to be lifted sucked above the well to enrich through progression holes uncovered by throttle plate. 

 

Clear that circuit and all will be fine again.

Might need ultrasonic bath.

 

 

Edited 28 February, 20188 yr by dvderlm