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Bogging at full throttle

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Cabriolet bogs at full throttle.

Have a problem with my 89 cabby fitted with a Weber 32 34 carb, have had the car around 2 weeks now, initial problem was that the car just cut out every 100 yards or so, the engine sounds sweet so was pretty sure it was down to the carb, after getting a good discount off the asking I bought it.

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

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1st job is check the fuel filler neck, shine a torch down it and check for any rusty holes then have a check in the fuel tank for any bits floating around inside which could block the fuel pick up.

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.

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Just an update regarding the bogging problem I’ve been having. I had the mobile tuner guy out again today, he spotted that the recently fitted cam belt was a tooth out and the timing had been set wrong, it was timed on the diamond instead of the dot.

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.

 

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Good to hear it's running right now, it is really easy to get the cam belt a tooth out as it moves when you tension it. At least when you next fit a cambelt if the car does not run right you know what's wrong.  :thumbs:

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.

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why would one tooth either way
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

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Spoke to early regarding the earlier mentioned fault, thought I’d go for a sunny blast after work yesterday, all was going well for around the first 5 miles or so, then it started playing up again, not quite the same as before though, instead of bogging at full throttle it just kangaroos and cuts out at any throttle position, must have died 5 times and only just made it home.

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.

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could be wrong but by one
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

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dot is for static timing, diamond for ignition timing with a strobe.
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.

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is the pump jet working
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

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Finally got around to looking at the golf again after a busy period, well since my last post I’ve done some more work on trying to make it run better, I’ve changed the plugs, plug leads, dizzy cap and rotor arm, I also fitted an .8mm welding tip in the fuel return as per searching this forum, seems to work for some cars.

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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