More Running Issues!!

[EastWesty]

Hi All,
Need some advice from some more technically minded people because I'm at a loss with my Split's Problem.Some background: My Bus is a 65 Westy Lhd,running a New 1600 TP VW Brazil engine built in 2001.When bought it was running badly, running a Bocar Carb and a Bosch 009 Distributor.It idled ok when warmed up but as soon as you accelarated the bus it would hesitate and stumble, you needed to rev and slip the clutch to get it moving.On the advice of a VW Engineer I know he changed the Carb and Distributor.Its now running a rebuilt Solex 34 Pict 3 Carb and a Bosch SVDA Distributor.Also a new Empi Clutch and rear trans mounts.It is slightly better pulling away.But still hesitates and stumbles when pulling away, but is drivable on a long straight road.Will cruise at 60 and oil temps are good.Have lost confidence and am a loss as to the next step.
Advice please!

Tomas

[Who.Me?]

Chasing ghosts can be frustrating. It's usually something simple though, so do the usual tune up procedure and choke adjustment first, then retest.

Also, check thoroughly for vacuum leaks in the carb and intake manifold, and all connections along the way. Fix any leaks and retune.

If it's still bad, measure the output of the accelerator pump on the carb. The procedure is on most workshop manuals, along with the procedure for adjustment. Make sure it's in spec. Not enough squirt and it will lean out on acceleration. Too much squirt and it will flood. Both are bad.

If the output is low after adjustment (my guess is that it'll be too low, rather than to high) check the accelerator pump linkage for wear and play. The linkage on my 'professionally rebuilt' 34PICT3 was sloppy as hell. I had to scavenge parts to repair it.

Fix, check and readjust.

If it's still low, loosen the accelerator pump cover but don't remove it. Pull the throttle arm down fully and hold it while you retighen the screws. That's how to preload the accelerator pump diaphragm to get the proper volume but no one ever seems to remember to do it.

Check and readjust. That's likely the best you'll get out of the accelerator pump adjustment.

If that doesn't fix it, I'd also check that the choke pull off is working correctly, and that the diaphragm is right.

This is more likely to be noticeable as the engine warms, but before it is fully off the choke. The problem goes away after about 10 mins running....

First check the choke adjuster with the engine stone cold. You should only be able to set the choke as far as the furthest step on the stepped cam. If you can set it on to the very tip of the cam, then the diaphragm is shit. Buy a good quality carb rebuild kit and replace it. Some have a slot in the stem that is too long. Those will let you set the choke on the end of the steeped cam. The over-long slot means that it takes too long to engage with the choke, so it doesn't pull off straight away, and you can get stumbling under acceleration while the engine is warming up.


I've also had one where the pull off was sticking. To check and fix that, undo the choke adjustment screws. Remove the choke element. Remove the choke pull off diaphragm cover screws and push on the diaphragm. If it's hard to move or feels gritty, lube the diaphragm shaft and the bore it rides through. When it's smooth, reassemble, adjust the choke and try again.
_________________
Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[EastWesty]

Hi Andy thanks for the very prompt reply,with very useful information.Will work through this.When I ordered a rebuilt Carb the same guy ordered me a Bosch SVA Distributor by mistake, which he informed me was correct!.However we fitted a second hand Bosch SVDA Distributor,possible I suppose that the Vacuum unit could be faulty?

[Who.Me?]