2.1 DJ judder at 2k RPM and 20mph

[McNab]

Hi All

Hoping I can lean on similar experiences from others onto he forum.

My '86 2.1DJ westy Joker is a daily driver and has always had a slight judder or 'bunny hop' effect when driving in higher gears (typically 2nd gear). I've always treated it as one of those classic car things and a bit of clutch slipping or adjusted driving style has usually gotten me around it being a problem too much... however as I've got a south of France trip planned, I've been subconsciously noticing all the myriad of things that may go wrong on the trip and this hopping has come most to mind, or it's gotten worse and now I'm noticing it more..

I'm not sure if this issue could be due to need of a new fuel filter, a new / cleaning of the fuel tank, proper cleaning of fuel injectors or something not fuel related such as clutch.

Fuel injectors have always been my initial thoughts of the cause for this, but it only happening at 2k and 15-25mph steers me away from this a little. I've carried out the 'fuel injector cleaner' without any noticeable effect and so I bought some spare injectors to get professionally cleaned and replace my current ones, but as I was close to clicking on an eBay service I started thinking of potential alternatives to the issues. (If anyone can recommend a fuel injector cleaning service they've used, please let me know).. ..

The fuel filter theory came about as I had this changed about 2 years ago at a garage as part of their service, and driving it back I noticed it driving a lot smoother. I changed the filter again last year without as much noticeable difference, but I also probably wasn't paying as much attention. I've got another but not yet got round to fitting it, but that made me think - if it is the filter; is this service interval typical or is there more to it...

That leads me to the fuel tank. Since I've had the van, I've always noticed I can't fill it up otherwise fuel leaks out of the top - turns out the expansion tank connections are missing, so could this lead to dirt in the tank causing the filter to clog. I think the fuel pipes have been replaced, but can't say for sure and could this be another possible cause of filter clogging. I know it's a good idea to get the pipes changed in any case, which is on the list but could be part of my fuel tank removal if it is.

Then I'm wondering could this be a potential early signal of clutch issue? The clutch does, very occasionally, groan a little - possibly on longer journeys or hotter days, but I've not pin pointed a common situation for this..

So, there, some of my spinning thoughts on a post that I'm hoping people can help direct into an experienced or educated direction to rule out first. I am tempted to change the filter next weekend anyway as I have one floating about, and it's not a massive undertaking..

Cheers in advance

[silverbullet]

More likely to be a bad earth return from the ecu/injector wiring harness. Check for green ring terminals on LH head and also at chassis connection nearby. Could also a be a sign of a failing ignition amplifier (TCI unit) but thats more likely to cause starting difficulties.
So-called "vanagon syndrome" is also another culprit but nobody seems to know precisely what causes it or the remedy, other than replacing everything with shiny new aftermarket parts.