Pierburg 2B5 vacuum circuit

Carbs; K-jet; Tanks; Lines; Filler necks, Senders; aftermarket fuel systems; Exhausts and Manifolds;air filters - standard and aftermarket

Moderator: Scirocco Register

Forum rules
Hints, tips and guides for repair and modification - the FAQ section on the main website is worth checking first for information relating to common faults and technical help. Useful posts and guides will be added to the FAQ http://www.sciroccoregister.co.uk/scirocco-faq
philipayton
Posts: 38
Joined: Tue May 24, 2022 8:03 pm
fill in the right answer: 15
Location: Dorset

Re: Pierburg 2B5 vacuum circuit

Post by philipayton » Thu Jul 21, 2022 4:03 pm

Checked the sender unit. Filter is clean as far as I can tell - I tried to add a picture but size is too large. No sign of any sediment or rust.

However, removed the inline filter and there are little bits in there. I will fit a new one and check that after a few miles. The car was stood for a while - so just on the off chance.

Realistically it will need new pipes I guess from tank to engine bay. I’ve done the gearbox so can get the car a fair way of the ground. Is it still too hard to do the pipes?

And finally there is no swirl pot. From the pump it goes to a small (30-40mm) plastic cylinder with the fuel return out of the side and supply to carb at the top.

I’ve put some octane booster in - will see if it makes any difference.

The timing was right per the book but I have advanced it a few degrees and it is running better. Idle is a bit high as a result.



philipayton
Posts: 38
Joined: Tue May 24, 2022 8:03 pm
fill in the right answer: 15
Location: Dorset

Re: Pierburg 2B5 vacuum circuit

Post by philipayton » Thu Jul 21, 2022 4:47 pm

Further update. Advanced the timing a bit more - symptoms almost gone. No pinking but must be a fair way from recommended. Think I will run for a while and see how it goes.



Flags
Posts: 28
Joined: Tue Jan 18, 2022 9:10 pm
fill in the right answer: 15
Location: Dorchester Dorset

Re: Pierburg 2B5 vacuum circuit

Post by Flags » Thu Jul 21, 2022 10:47 pm

Hi Phil, fairly sure but the early FR 1600’s with 2B5 carbs didn’t have a swirl pot, just a small plastic T piece restrictor pot joining the feed and return pipes with an outlet to the carb.



RussGLAuto
Posts: 283
Joined: Sat Jul 14, 2018 11:51 pm
fill in the right answer: 15
Location: Spalding

Re: Pierburg 2B5 vacuum circuit

Post by RussGLAuto » Fri Jul 22, 2022 4:42 am

Hi Phil,

100% the problem is rust clogged in the hard fuel line if you have bits in the filter. Change that first. Not difficult, just time consuming. Held in place by metal tabs. Rubber grommets to stop rattling too in various places. Try not to bend the old pipes when removing, they become the template to shape the new pipes before installing.

Then you can change the filter and give the jets a final blow through.

You do need a swirl pot. They were originally fitted with one. Haynes manual will show you the correct mounting position.

Glad your getting to the bottom of it!! Nice one.


Daily Driver - 2017 Volvo XC90 T8 Twin Engine - Polestar - Arctic White
Weekend Wagon - 51k 1982 Mk2 Scirocco 1.6 GL Auto - Diamond Silver
Other Half's Wagon - 2020 Renault Clio RS Line - White
Daughters Curb Scraper - 2016 Fiat 500 1.2 - White

RussGLAuto
Posts: 283
Joined: Sat Jul 14, 2018 11:51 pm
fill in the right answer: 15
Location: Spalding

Re: Pierburg 2B5 vacuum circuit

Post by RussGLAuto » Fri Jul 22, 2022 4:51 am

Hi Phil, here's the link to the separator pot, if you clic on the 'fits vehicles' link it shows you its for a 1.6 FR engine which yours will be...

https://www.heritagepartscentre.com/uk/ ... etrol.html


Daily Driver - 2017 Volvo XC90 T8 Twin Engine - Polestar - Arctic White
Weekend Wagon - 51k 1982 Mk2 Scirocco 1.6 GL Auto - Diamond Silver
Other Half's Wagon - 2020 Renault Clio RS Line - White
Daughters Curb Scraper - 2016 Fiat 500 1.2 - White

philipayton
Posts: 38
Joined: Tue May 24, 2022 8:03 pm
fill in the right answer: 15
Location: Dorset

Re: Pierburg 2B5 vacuum circuit

Post by philipayton » Thu Aug 04, 2022 9:41 am

Update on this in case it helps someone else at some point.

Car is now running sweet. It was many small things - vacuum circuit, timing and a poor HT lead at the coil.

Fixed all of that but still was suffering what felt like fuel starvation. So as an experiment I bypassed the new swirl pot and went back to how it was with a simple Y piece.

And now the car runs great. There seems to be different opinions as to whether the swirl pot is needed on a carb engine. In my case not.

I will change the fuel pipes at some point but for now it seems unnecessary.

Thanks for the advice given.



Flags
Posts: 28
Joined: Tue Jan 18, 2022 9:10 pm
fill in the right answer: 15
Location: Dorchester Dorset

Re: Pierburg 2B5 vacuum circuit

Post by Flags » Sat Aug 06, 2022 9:41 am

All 3 FR engines I have owned or worked on with a 2B5 have not been fitted with a swirl pot but every 2E2 have.
Just because VW Heritage list it doesn’t make it right.
Glad you have it sorted now.