New Problem With SU HIF6 Carbs

[nige71]

Hi All

Just done service kit from su carbs and now my problem is it will start up
and run for about 20 to 30 seconds and then slowly start to cut out until
engine stops fuel pump pumping fine into bottle .so mustt be happening
in carbs.??

could this be caused by sticky floats or by floats being set to lowe
as was running ok before service couldnt see both floats sticking at same time but both may have been set to lowe ????????

any info would be great.

Thanks nige

[kiwicar]

Hi
Yup you seem to be on the right trail, sticky float needle or float set too high. the other place to look is for a fuel filter becomming blocked by crud in the tank, when you switch off it falls back from the filter unblocking itself until you start it again when it flows back into the filter causing a restriction. Another place to look is after the filter for a largish bit of crud blocking the needle valve, then falling back when the engine is off. My final suggestion is a tired fuel pump that will give pressure on start up and in free flow into the bottle but quickly overheats and does not make pressure against the regulator when running.
Best regards
Mike

[ThatV8sound]

Got HIF6's on my P6, to set them I remove the bottom of the carb (4 bolts) and with it perfectly upright and inverted check the float level with a straight edge, through the bottom of the curve of the float and body casting side to side, can't remeber the gap but there should be one listed, the fuel pick up / jet might get in the way, so just dismantle and have the float and needle mounted. Adjustment by gently bending the brass tab. Needles can stick, bottom pin should be sprung if it doesn't do this anymore its time for a new one. I've never had any success without changing the seat as well. Dead givaway is usually the carbs dumping fuel via the overflows. They are not very forgiving for poor float level. If you're running these on a Rover P6 V8 check your fuel return pipe to the tank, it goes in at the bottom of the tank and can be covered in rubbish, try blowing it through with an airline ( filler cap open) and you should hear it bubbling away. Good luck.