keslider55 Posted November 28, 2010 Report Share Posted November 28, 2010 hey guys ive added some pics of my 4k with the twin su carbs fitted. ive hooked up the fuel feed lines to both fuel bowls and left the other opposite pipe on the bowls to vent to atmosphere. car runs perfect and everything working fine exept there is fuel pissing out one of the breathers. or what i think are the breathers. can u tell by looking at the photos if ive hooked it up wrong or if somethings broken. ps if i block off the leaking line the car misses then stalls. Quote Link to comment Share on other sites More sharing options...
Redwarf Posted November 28, 2010 Report Share Posted November 28, 2010 Yep they do that. Who set up your SU's? The guys that did mine spaced the bowl with about 3/8" of exhaust pipe (for various reasons unknown to myself, suffice to say it worked.....). It still ocasionally leaked fuel, and thus I ran a tee'd drain line (2 carbies) to somewhere out of the way for surplus fuel to exit to. I'll see if I can find a pic. Quote Link to comment Share on other sites More sharing options...
kangaroosa Posted November 28, 2010 Report Share Posted November 28, 2010 I can't find a pic of mine. But mine just had some fuel hose attached to the vent and then was cable tied to the fuel bowl, so any fuel that leaked was vented downwards and away from the exhaust. Mine never leaked any serious amount of fuel. Might be worth checking your fuel pressure to make sure the needle and seat is not being overpowered. Quote Link to comment Share on other sites More sharing options...
19914afc Posted November 28, 2010 Report Share Posted November 28, 2010 its not a fuel return is it? Quote Link to comment Share on other sites More sharing options...
keslider55 Posted November 28, 2010 Author Report Share Posted November 28, 2010 I don't thing its a fuel return because if u block it the car stalls straight away. Return wouldnt do that. By the way the piston that you can see through the ram tubes is a bit sticky on the rear carby. This is the on the same carby with the leaking hose. Could that be related??? don't think fuel pressure is the issue cause I'm still running standard mechanical pump Quote Link to comment Share on other sites More sharing options...
Redwarf Posted November 28, 2010 Report Share Posted November 28, 2010 No it is not a fuel return. It's a breather. Quote Link to comment Share on other sites More sharing options...
keslider55 Posted November 28, 2010 Author Report Share Posted November 28, 2010 So what should i do cause its coming out quite alot. Its not pressurized but its definatly just flowing straight out. Should i run it for longer to see if it stops??? If not what do i do??? Thanks guys Quote Link to comment Share on other sites More sharing options...
Trev Posted November 28, 2010 Report Share Posted November 28, 2010 Sounds like the needle and seat are stuck open. Quote Link to comment Share on other sites More sharing options...
keslider55 Posted November 29, 2010 Author Report Share Posted November 29, 2010 Hows the best way to check that??? Quote Link to comment Share on other sites More sharing options...
Trev Posted November 29, 2010 Report Share Posted November 29, 2010 Take the top off and see if the float is stopping the flow when raised up. Quote Link to comment Share on other sites More sharing options...
keslider55 Posted November 29, 2010 Author Report Share Posted November 29, 2010 All sorted the needle and seat was loose so not sealing!! Thanks so much guys. Made it alot easier! Cheers everyone Quote Link to comment Share on other sites More sharing options...
keslider55 Posted November 29, 2010 Author Report Share Posted November 29, 2010 All sorted the needle and seat was loose so not sealing!! Thanks so much guys. Made it alot easier! Cheers everyone Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted November 29, 2010 Report Share Posted November 29, 2010 Do you run a fuel pressure regulator?? SUs only like low pressure, one or two psi, and stock you will be pumping 6psi or so I think. One of mine overflows occasionally, very typical of SUs. I used to carry an empty Coke can to smack the rear Hitachi on my Datsun 1600, same problem. PM me with things you discover, I'm finding the SUs to be full of tricks when it comes to needles, springs and oil in the dashpots. I'm still running stock springs and home-made needles with Johnson's Baby oil, but I'd like to video the throats at full throttle to see if they open right up. The oxy sensors and the fuel mixture display has been great for tuning, well worth doing with SUs. Quote Link to comment Share on other sites More sharing options...
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