Gday all,,,
Been having a bit of fun with my 1.8l Mk1 Golf,, new carby
Finally took old pierburg carby out and put in a weber, BUT, got the same weird problem - sucking air from the fuel intake before the air cleaner (I can see the bubbles coming in), gets worse under load and stalls.
Setup was for old pierburg was; tank-filter(new one)-pump-carby (with a return back to tank just after pump, no return from carby with peirburg). Now I have weber setup is; tank-filter-pump-carby (with return to tank from carby) but I still get the bubbles coming from the tank into filter.
I found that when I blocked off fuel return the air stopped and car ran fine. Now trying different setups, I reduced the return fuel line size, hleped a bit but still air. Next I redirected the fuel return from carby back to the fuel into carby just after the pump (works fine)..
Then tried putting a T junction into the fuel line back to the tank, no good though, bubbles are back..
Any ideas?
Cant remember but I think last owner of the weber mentioned he never had a return as had it set up for rally / go fast.....
Daaaaave
Great to be back on road though, adaptor plate was a bugger to find, ended up welding an extra bit onto another to re-wrout the water, seems fine
Runs a lot quicker now too,,, good stuff,
pi22api22a wrote:.....sucking air from the fuel intake before the air cleaner
...er did you mean 'berfore the fuel filter'?
I'm going to sound stupid here, but why have you got a return line from the carby to the tank? I've seen plenty of Webber carbie set-ups, but never seen a return line used - what purpose is it supposed to serve?
R
🙂40hp, 6V and ...er... slowly making improvements
😂
It's nice to be important, but it's more important to be nice!
Founding member of the Gold Coast Dub Club Inc. 🙂all mk1 golfs had a return line from memory.
I have seen this exact problem years ago, and I cant remember what was done to fix it. Possibly just not run the return line, and fit a pressure reg, but I cant be sure.
If the pressure is around 2-4psi, and you dont have any float bowl issues with flooding etc, I would not run the return line.
Ah thanks for the tip,
Yeah I meant fuel filter (not air, whoops),
Only been running it this arvo, does not seem to flood it, runs pretty well, I'll try simply blocking off the fuel return then (fuel out of carby),,
Q: If webbers carbies dont usually use return lines then whats the fuel out used for? Or is it just blocked off?
Thanks heaps
Daaaave
sounds like its a problem with where the fuel return goes into the tank blowing bubbles that the supply line simply sucks in and pumps to the carb.
you said the same problem, I'm guessing it was there with the old carb too.
as for return vs. no return, generally speaking old cars dont run a return line, especially if using a mechanical fuel pump, whereas the later model car (imports before local) tend to have a return line. I believe its got to do with tighter emission controls, especially at idle in heavy traffic, fuel can be in lines in a hot engine bay for a few minutes, which can make it heat up and even boil in the lines, causing vapour lock, with a return line, the fuel is constantly circulating, therefore keeping cool, and when vapour or air does get into the supply line, its more likely to be bled back to the tank via the return line, rather than interrupting flow to the carb, possibly causing a slight lean situation, which may alter AF ratios and chage emissions out the tailpipe.
thats my theory, and based on what I see everyday, most issues in fuel systems are only because they are too complicated due to the tightening of emission control laws.
oh, its not really Danielle, its Ryan.
1968 pearl white beetle:kiss
1600 engine😉
soon to be supercharged 🤘🤘
1970 and 72 Squarebacks 70 soon to be rotor powered
hey Dave
the reason i would say the weber has 2 fuel lines is for if it was in a twin carb setup
alot of webers come like that
generally u just buy a new banjo fitting that only has one inlet line for a single carb installation
are they both the same size?
cos generally return lines are alot smaller
main lines are usually 6-8mm and returns are normally only 4-6mm
hth
Joel
Ah that must be it Joel, the return (or fuel out) from the carby is the same diameter as the fuel in, so must be for 2nd carby,,,, I'll just block it off then and see how I go (carry spares with me anyway),, already blocked off pipe leading back into tank.
Yeah I agree Ryan, fuel line return to tank must enter near the point where fuel intake to pump is, carries bubbles with it. Weird thing is the original setup had return going back to tank from a T piece on the fuel pipe between pump and carby intake (but the old pierburg was a nightmare, so many hoses & crap, still dont know what they all did, most stopped working I reckon)
Cheers for the advice all,
Daaave
