Intermittent problem.

[vwadam]

Can anyone help?

I'm having problems with the engine in my squareback. Unfortunately it is very intermittent.

It feels like a misfire/stuttering when I try and accelerate. It will start and idle fine. I can rev it and it sounds fine. However when driving under any sort of load it stutters.

I drove to ninove a couple of years ago in it and it started when coming back into uk. So far to try and cure it I have cleaned the jets in the carbs, put new rubbers on the carb balance pipe ends, taken fuel tank out and cleaned it, changed the tank outlet and filter, changed the distributer for a vacuum advance one, put an nos fuel pump on, changed the coil and checked timing and valve clearances. It can be fine for certain journeys and then just starts happening.

Went to ninove this year with no issues, went to the heretics meet last night and drove fine there (about 45 mins), went to leave and the problem is back. I managed to drive it home by just touching the accelerator and driving very slowly. Any kind of effort to accelerate caused it to stutter. If I dipped the clutch and revved it, it sounds great. But try anything under load and it doesn't want to go.

It has the original engine case, 1600 single port heads, twin solex carbs, vac dizzy with points and blue coil.

I'm thinking its carb related but have run out of ideas.

[Marko]

might be worth trying a another pair of carbs and rebuild them 1st, have you played with the accelerator pumps on the side of the carbs? there are 3 positions they can be in to squirt extra fuel, may be worth a try...

[vwadam]

Only thing I've done is stripped them and cleaned the jets. It runs a little rough for the first minute or two when engine is cold but when warm it's fine (when it works).

I see Bert has a pair on the samba for sale. Mine a 32-34 pdsit-2 and 3. The only thing which seem different is mine don't seem to have cut off jets on either of them.

[Marko]

are they bus ones or proper Type 3 ones? they should have the cut off jets in. there is so many places dirt can get trapped in them it's unreal. I spent ages blowing mine out with compressed air and still missed some in the part with the ball bearings so had to do it again!

[vwadam]

Not sure how to tell the difference. Have another couple of spare pairs in the garage. The spare 32-34 don't have cut offs but I have a pair on 32 pdsit which do.....

[Marko]

the correct ones have the bridges over the throats for the air filter assembly to bolt to.

[vwadam]

All the ones I have seem to have that....?

Where there any differences between early and late?

[miketyp3]

Pre 66 carbs don't have the cut offs. They used a mechanical device in the fuel line before then (twin carb only - the single carb engine was less prone to running on).
I don't think there's much differance between early and late - I've certainly swapped early to late and vise versa and not had a problem.

From what you say it sounds like it could be a ignition advance problem - most likely a failure of the vacumn diaphram, but could be as simple as a split pipe.
Worth checking if you have not already.

Mike

[vwadam]

Where and how does the cut off valve fit??

When I changed the dizzy from the 009 to the vac dizzy I checked the vaccum worked and fitted a new vaccum hose. The issue was there with both distributors which made me think it was more likely a carb problem everything else (ignition related) has been changed apart from the wiring itself.

[vwadam]

Seen pictures of the inline valve but it seems to have 5 outlets/inlets....

[miketyp3]

Maybe look at the accelerator pump system then. Its not load related like the vacumn advance, but the engine will need more fuel under load, so if its under delivering then it could be it.
Its an easy thing to check... with fuel in the float chamber opening the throttle should result in petrol being squrted out the brass tube in the carb inlet. There is a set volume of fuel that should be dispensed, which I don't have to hand, but I can look in my dealer manual at home and let you know.
If its a blockage, like Mark said, it might be worth arming yourself with a couple of rebuild kits stripping the carbs down making sure everything is clear and getting them set them up properly.
There's a guide to the twin carbs here: http://www.thesamba.com/vw/archives/man ... /index.php
which I find quite useful.

Regarding the inline valve, it also forms the "T" piece and works by using the pressure from the pump to open the valve, so the lower connections are inline on the inlet fuel line, and the upper 3 are from the pump outlet two the carbs.

Mike

[vwadam]

Thanks for the help and info.

A few things to try now. Fingers crossed.

[broady_6]

Fuel pump???

Your not demanding when at idle or reving. Start driving down the road and it wont take long to empty the float bowls if the fuel pump isnt delivering at full capacity

[vwadam]

I did swap the fuel pump for a nos one I picked up. The carbs are the only thing I haven't physically changed, just cleaned jets. I've sent a pair of carbs to Bert to be rebuilt and have decided not to touch anything else at the moment until I've fitted the carbs and tried it. If I fiddle with too many things in one go I think I'm going to find it hard to narrow down the issue.

Thanks for all the suggestions so far.