2.25 petrol - lurching - especially up-hill

Greetings,

Got a bit of a problem with my new S3. The engine sounds lovely, and it's really nippy compared to the 2.5NA in my 90, but it has a problem sometimes, especially when flooring it going up hill. The steeper the hill, the worse it seems, although very occasionally it does it on the flat, but it's always when you floor it. It seems to just hit flat spots, which ends up being quite a lurchy ride, it tries, but just keeps on lurching and lurching. It's not always so bad, but there are a couple of hills near me where you're almost guaranteed to get the problem. I had the same problem on another car, and that was one of the coil packs, but so far I've tried new NGK sparks, Lucas HT leads, a new coil pack, a whole new distributor (so distributor cap, points, vacuum advance, and condenser implied), and it seems to have not made a difference.

Any ideas on where to look next?

Cheers!

Not sure if it's entirely relevant, but when I stop the engine, sometimes it fires up again, or tries to a couple of times. It'll definitely have stopped 5 seconds or so after you switch off the ignition, but that's a bit weird isn't it!

snother thing. I clean out my fuel filter, and it looked ok really. the filter is definitely ok now.

Fuel mixture? or float height? what carb is it? zenith, or weber?

Thanks for the reply. It's a Weber carb. Would either of those cause such an intermittent problem? My friend's got a Gunson colortune which I could borrow if the mixture could be at fault, but I don't really have a clue about the float height. I haven't touched the carburettor to be honest. I was sure it was electrical, but having replaced the whole ignition system, I'm willing to defer

My friend actually has a similar problem with their 300tdi defender - but I won't muddy the waters with that

It's a possibility, float height is important, and can make a difference on a slope... is it only uphill? have you cleaned carb? or is it new? To be honest, I have had probs with mine since getting it of ebay cheap... haven't had it totally apart, but the filter on the fuel in section was really gummed up... cleaned it out, and it still is lumpy... but pretty much all the time until warm. The float height is about 7mm as can be seen in this page.Weber it's worth setting it up properly, and seeing if that makes a difference? also an in-line fuel filter before the carb helps. Good luck.

It's not just on a slope that I get the problem, but it's _always_ worse on a slope

I'll have a pop at cleaning up the carb and firing some compressed air through it and things. Hopefully I'll get somewhere eventually I guess I'll need to get a seal/washer and gasket kit to do that though.. more expense! The money pit deepens hehe

Thanks again for the reply

Hehe, yes money pit indeed... but.. there are certain advantages.. so float height seems to be between 6.5mm and 13mm from top of float to bottom of gasket. Looking into it, it does seem to make a big difference to running.. a good clean will also help loads, but yes, at least a new gasket set is in order. All the best.

Worth checking the filter in the tank (take off the cover under the driver's seat for access)
and the filter in the carb. It could even be a leaky or crudded up fuel pump, or a crudded up carb. If you can smell fuel in the engine oil it's usually the pump diaphragm that's leaking.

you know what, I think the engine oil might smell a bit of petrol. that's interesting..

I'll check all of those things. I haven't got around to doing anything else yet. Hopefully tonight, or some other night this week, just not sure if I've got time until the weekend!

The pump diaphram, that's interesting.. where is that? mine seems to smell a bit excessively petrolly too, and the pump was a little sporadic with it's flow. It's an su electric pump, I need to get it apart to clean it. would just prefer to fill it with LPG all the time, but there isn't a garage very close!

The mechanical pump bolts onto the side of the block and is driven by the camshaft so if the diaphragm leaks it dribbles fuel into the engine. The SU electric pumps were, I think, fitted to the 6cyl engines which had no mechanical pump so won't leak into the engine. Looks like your pump is rebuildable so it might be worth seeing if there's a rebuild kit for it.