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my engine hesitates at low rpm

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4 of 50 Commited Dubber

71 posts · joined Sep 2003 ·

#669343
thanks for considering this problem:

I have a 77 micro bus. 1 year ago i had the motor rebuilt. since this time it has never run well.

the problem is the motor will hesitate as you put the foot on the gas through each gear. it is as if the engine never warms up properly. at higher rpm it runs fine. additionally there is black soot in the exhaust and a smell of petrol.

Naturally i find the above situation disturbing so i have had 3 seperate mechanics look at the problem. (This engine has cost as much as a Barina and right now i would swap it for one if given the chance.)

the carbies are twin solex with no choke. a friend of mine says the right side jets are spraying fuel onto the butterfly valve (apon which it bounces up instead of going on down)

we have checked and rechecked the timing.
electronic points set was fitted when rebuilt.

My questions are
1/ should i send the carbs away or buy a new set and start again?

2/ most of my trips are short. wouldnt i be better off with chokes

VWCOOL 23 Windows of Awesome

5,158 posts · joined Jun 2003 ·

#669350
when you say Solox with no choke, do you mean Kadrons? Aftermarket ones - not original? Sounds like they need setting-up properly...?
Pay your debts, CxxT

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#669359
1 where do you live

2 who have you taken it to PM me if you like

3 i may be able to suggest someone who may have more knowledge
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#669385
may be sucking air through the throttle shafts as well they tend to wear in the stock 2L carbies
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#669448
Maybe the accelerator pumps need adjusting
pumping too much fuel every time you touch the throttle

or the distributor timing is incorrect..

have the mechanics been VW mechanics???

Lee
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---

_me_ Seriously Crusin Dubber

125 posts · joined Jan 2006 ·

#669693
i have the same problem. and i have kadron carbies.

coincidence?
74 > 54

modulus Veteran Volks Folk

2,009 posts · joined Jul 2003 ·

#669698
As well as the carburettion, you should check that the ignition timing is right, as Lee mentioned, and also that the distributor vacuum advance is fully functional. It's easy to have the distributor bench tested.

hth
Peter Hill
1975 Type 2 Double Cab
modulus.com.au

kombi_kid Moderator Good Kid too many projects

124 posts · joined Aug 2002 ·

#669761
also check your manifold vacuum elbows as they tend to slip off/breakdown these are the 2 elbows balancing the manifold's
cheers
rhys
it aint just cool its aircool'd

mnsKmobi Wolfsburg Wizard

589 posts · joined Aug 2002 ·

#669911
Do you have the stock vacuum advance distributor or a 009 (mechanical advance only)? When you say you have checked the timing have you used a timing light and have you checked the advance with and without the vacuum attached (assuming stock distributor)?

Lack of chokes is not a huge problem with twin carbs because the manifolds are short. I have twin weber icts and just let the engine warm up for a few minutes in cold weather. Now a single weber progressive, that's a different story!

aggri1 Insano Dub Head

824 posts · joined Dec 2003 ·

#669914
I'm intrigued that you say twin solex with no chokes too, as the standard 34PDSITs have electric chokes.

I too had a motor rebuilt and used some 'rebuilt' carbies at the same time, and have never got it running well. These carbies have caused me very much grief, stupid things, mainly with a MAJOR hesitation at low engine speeds, much as you describe. I never figured out what the issue was and went back to an old set with leaky throttle shafts and all which ran better than the shiny clean ones.

But as the others have said, timing (incl. functioning distributor) is easy to check. That was not my problem however.

Accelerator pump not being right makes a huge difference. Either too much or too little flow and also where it gets squirted even - during my investigations I noticed a difference just in where the little squirter tube was pointed. Your friend might be on to something there.

Good luck dude, these things suck. No wonder the FI is so beloved by many (but strangely not the mechanics in Melbourne I've spoken to). These carbies have put me off the 'superior' TypeIV, just 'cause I have no running issues whatsoever with the good little SINGLE CARB 1600 single port in the '69.

Cheers, A.

EDIT: oh, when I took mine to a mechanic, he made it run richer to try to get around the hesitation at low speed. That was only successful in that it became so sluggish at all speeds that the hesitation became barely perceptible. That obviously is not a feasible solution. Hopefully that hasn't been done to yours. I mention that because it sounds like it's running rich (you mentioned soot and petrol smell). Rich running is bad of course and I think that that should be dealt with - get rid of the known problems first, then find the real problem.

westi what the

1,610 posts · joined Aug 2005 ·

#671022
don't rev it down low.
give it the beans,keep the rev's up high and your problem will dissapear.
down sharon.

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#671103
westi wrote:don't rev it down low.
give it the beans,keep the rev's up high and your problem will dissapear.
Spoken by a true bean giver.

All above is good info, at very light throttle, a lot can be caused by linkages, everthing fitted correctly/securely, both carbs balanced then actuated EXACTLY at the same time...
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

4 of 50 Commited Dubber

71 posts · joined Sep 2003 ·

#671840
Thanks for all the replies
in the mean time i have had some work done
problem is better but still there

thanks vw54 i will contact your man in Taree

Ben