Bogging at full throttle
Posted
#1617227
(In Topic #221058)
Settling In
Cabriolet bogs at full throttle.
Since then I’ve replaced the rubber gasket between the inlet manifold and the carb plus I bought a Weber service kit, I removed, stripped, cleaned and replaced all the gaskets and rubber parts.
Made a world of difference, the car idles fine, revs clean and pulls well, the issue I still have however is this, when I floor the throttle it bogs heavily and will cut out if you keep your foot in it, lift off a bit and it returns to normal.
Another thing I’ve noticed is when stationary with the filter box removed I can see fuel vapour coming out of the top of the carb when it bogs if I floor it.
Ive had a mobile tuning guy out today and he’s adjusted the timing and set the emissions, he’s checked all the electricals and vacuum pipes, his conclusion is a blocked exhaust causing back pressure.
Only thing is it bogs at any revs when flooring the throttle, so my thinking is at low revs there can’t be much back pressure, it’s almost like when the second choke opens it bogs and pushes fuel out of the top of the carb..
The tuners suggestion is to remove the back box and recheck, then if no better remove the centre section, before I do this I though I’d run it buy the experts on here.
Any suggestions guys?
cheers.
Last edit: by davearnill
Posted
Local Hero
The Webber carb can suffer from to much petrol getting returned to the fuel so you can try and restrict the flow to see if that helps.
More info here….
http://forum.sciroccoregister.co.uk/viewtopic.php?t=15397
1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.
Posted
Settling In
I also managed to poke a screwdriver through the rusty back box, seems like it’s probably causing back pressure after all, anyhow, no more bogging down, pulls a lot harder and revs cleaner, I’m hoping a new back box will make it even better.
hope this helps.
cheers chaps.
Posted
Local Hero
1988 Mk1 Golf GTi Cabriolet 1.8cc DX, K-jet. Daily drive. 317,000 miles and counting
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.
1978 Mk1 Scirocco GLS 1.6cc FR, Webber carb. Weekend toy.
Posted
Regional Host NE
make any difference ?
Do not know a lot but willing to help if possible
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
Posted
Settling In
Wierd thing is when I’m parked up it revs freely with no probs, the tuner chap is on holiday now so don’t think I’ll call him till he gets back, don’t want to spoil his fun.
I changed the fuel filter around 50 miles ago, the same time I replaced the carb rubber gasket and serviced the Weber, the fuel filter has a bit of dirt in it already though, I’ve checked the filler neck, no rust inside and the outside seems solid.
Im still thinking fuel starvation could be causing probs, only thing is I’d only expect this to show its hand under hard acceleration, ive just received a few various sized welding tips to try and reduce the fuel return, will see what happens..
Im still loving the car but getting a bit frustrated with the running probs, will hopefully get to the bottom of it soon.
Thanks for your help chaps.
Posted
Regional Host NE
tooth ?
Do not know a lot but willing to help if possible
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
Posted
Old Timer
the weber carb always does this, don't know why they have a reputation for being reliable.
seen a few bypass the vapour separator and run the fuel line straight to carb from the pump and plug the return line.
Posted
Regional Host NE
on the second venturi (choke))
Do not know a lot but willing to help if possible
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF
Posted
Settling In
After competing all this work it’s actually running a lot better but it still splutters with full throttle, lift off a bit and all good, I’ve did 200 miles last weekend without to much bother.
I still want to chase down the spluttering problem so decided to replace the Weber with a new Weber, as the car had been sat around for so long I though why not.
after fitting the new carb the spluttering has gone, can floor it and it pulls much better, but still not perfect, it idles a bit lumpy now so am gonna get it tuned again next week.
Given the new carb I thought I’d remove the welding tip from the return and see how it runs, well I only made it out the drive and into second gear before it cut out, put the restrictor back in all good again.
It seems strange that it still needs a restrictor in the fuel return to make it run, has anyone removed the swirl pot altogether and deleted the fuel return?
Thanks for all your replies and suggestions guys, really helpful this forum, be stuck without it..
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