13 replies to this topic

[charliefarlie37]

Got a problem with my carb, after a while it pumps fuel out of the overflow. stripped out to check for dirt in float valve but its clean, fitted new needle valve assembly and still does the same???
set up is 988 engine, hif 38 carb, electric su pump at rear, plastic inline filter under bonnet plus running the gause filter in the carb too... baffled

[nicklouse]

did you set the float height correctly?

[charliefarlie37]

morning 😊
i set the float according to a you tube video i found, using a ruler across bottom of carb housing?
ive had the float submerged in water to see if its got a hole in it and therefore takes in petrol but it checks out ok.
it doesnt overflow straight away, usually after 5 or so mins of running,
would the engine breather cause this, would it run ok without the breather attatched?

[Ethel]

Could the pump be faulty?

 

Still most likely to be the float or valve. The float can wear on the pivot shaft causing it to stick. Is there a a sealing washer under the valve?

[charliefarlie37]

sealing washer? between the valve body and the actually carb? if so, no, no washer, just a fine gause type filter under the valve assembly.
everything seems ok with the pivot .

[Ethel]

Sorry,

 

Looks like Hif's have a taper fit rather than a washer. Might still be worth looking at potential leaking around the valve threads etc.

[charliefarlie37]

fuel up the threads could indeed be a possibility.
just been to try the carb again on the mini and do further investigations and its still doing the same thing.

i dont think its the fuel pump, you can see each pump of the fuel into the plastic inline filter and its only just keeping the bottom 1/4 of the filter full.
the fuel starts to seep out of the overflow for probably 30 seconds and then builds up to a full spurt.
stripping the carb again to check things....
one thing i did try was turning the carb upside down and blowing in the feed pipe, the float valve is defo shutting as i couldnt blow air in .

on a positive note my wiring loom conversion i made to put the pup back to a single centre clock all works 😊

[Retroman]

A new float valve should not be the issue, assuming its not cross-threaded and tight

 

Whats the electric pump?

 

An Su carb only needs low pressure

[charliefarlie37]

its a su pump located under the load bed, the car has only just started doing this since changing carbs from a larger hif44 to the 38. i changed float valves over from the original carb to this one as the original one worked fine. might try some liquid ptfe on the threads

[nicklouse]

morning
i set the float according to a you tube video i found, using a ruler across bottom of carb housing?
ive had the float submerged in water to see if its got a hole in it and therefore takes in petrol but it checks out ok.
it doesnt overflow straight away, usually after 5 or so mins of running,
would the engine breather cause this, would it run ok without the breather attatched?

well not knowing if the info on "youtube" is correct try the correct source of info

http://sucarb.co.uk/...tter-reassembly

[Retroman]

Ok Bit confused, is it the new float valve or 2nd hand..?

 

And I would check the float level again too...also question the metal tag that closes the valve, I wonder if its weak

 

You did mention the breather, is the float chamber breather blocked ?

[charliefarlie37]

hi, sorry for the confusion, ive tried alot of things and got stumped.
after changing to the hif38 and this problem arising i initially thought it was the float valve and changed the valve assembly for the one out of the previous carb as this i had no issues with.
this didnt clear the overflowing problem up so i decided to buy and install a new float valve assembly.

float height has been checked and checked again, even compared it to some other hif carbs i have laying around.

just stripped the carb again, reset float height and checked valve for leaks using some petrol around the needle itself and compressed air down the fuel pipe ( carb upside down on bench) no bubbles whatsoever until releasing the pressure off of the needle valve.
hopefully will finish work at a resonable time and refit the carb and try again.

mrs is now moaning as i stink of petrol haha

[Retroman]

Modern fuel isn't a nice smell....going back it used to smell good...

 

My mrs complains about me cooking black crackle paint,

 

Its not an issue...cooker hood on full bore, window open, stink only takes about 3 hours to go...lol

[charliefarlie37]

haha, i think my life wouldn't be worth living if i used the oven for anything car related.
had enough aggro when i was soldering up my dash wiring loom on the kitchen side... women pfffft lol