Carb problems, volume 297...

[GroovyCarrot]

So, my new Weber TLA 32 has arrived, I've fitted it, everything's running sweet as a nut.. until I've been on the road about 5 minutes, then the performance gradually starts to drop, until it reaches the point where it stalls, and no matter what choke setting or how much throttle I give it, it just refuses to restart. It'll occasionally just catch on full throttle, then sit there at about 500 rpm struggling away until it dies again.

This happened on the way to work this morning, where it stalled in the middle of a rather nasty junction and wouldn't start until I'd been churning it over for a good minute. It also happened on the way home from work this evening, where it stalled outside my house. Very convenient, if it hadn't been in the middle of the road.. This time I actually had to run the starter for a minute or so leave it five minutes, come back to it and give it another minute of starter before it finally caught properly. Each time, when it finally does catch it suddenly runs perfectly, flies straight up to the red line in a rather unnerving way before I realise that it's finally started and ease off my right foot a bit.. but once it's done that, it'll sit there perfectly happily at 800rpm with the choke right in and not have a problem at all.

So.. Any suggestions? Kinda thought my carburettor problems were all done and dusted now

[Tahrey1043]

it hates you, you'll just have to get another car

on the other hand, how much did you check it out before fitting it? these troubles might be the reason it was being sold. something jamming up / worn out on the insides...?

[GroovyCarrot]

Nah, it was never used.. the condition of it was a testiment to that, it was absolutely gleaming, and didn't have any trace of the rubber mount that usually gets all over the bottom surface of it.

To be honest, I'm beginning to accept that first option.. I'm getting tempted just to say sod it and go and buy a nice 1.6 mk2 golf... but, I'll prod around a bit tomorrow and see if anything reveals itself.

[bstardchild]

Grooovy - just put a decent in line fuel filter in the line will ya

[GroovyCarrot]

It has one Not brand new, but it's only been in there for a year or so, it's only covered about 9,000 miles worth of petrol..

[optima21]

it could be that the choke is switching off too fast if its cold. I had this trouble years ago with mine and ended up disconnecting the electrical heater in the choke.

the other thing is that it could be carb icing and over the years I had loads of trouble until I fitted a permanent warm air feed for use in winter.

[GroovyCarrot]

It has a manual choke though.. does that open itself automatically? Would have thought it was entirely cable operated..
I'm going to give the permanent warm air feed thing a go, as I don't trust that vacuum operated switch thing at all.. although it seems strange if it's carb icing that it would keep turning over for ages and then finally just catch and run perfectly..

[bstardchild]

It has a manual choke though.. does that open itself automatically? Would have thought it was entirely cable operated..
I'm going to give the permanent warm air feed thing a go, as I don't trust that vacuum operated switch thing at all.. although it seems strange if it's carb icing that it would keep turning over for ages and then finally just catch and run perfectly..

Manual choke is exactly that - manual - it won't come on on it's own

I've had loads of webbers - thats why I recomended you went for one

I think you'll have to help me out here - what i need to know is

- when it doesn't start are the plugs wet or dry

- Is it a mechanical ful pump or electrical

So Plugs wet or dry

If they are wet then the problem will be detritus getting into the float needle seats and allowing excess fuel to choke the engine - basically you are flooding the engine and then it's a b'stard to restart but once it does you are away again untill circumstances dictate it floods again

If they are dry then the problem will be insufficient fuel

- Blocked filter would be a good bet - it will slowly starv the car of fuel leading to the symptoms you describe - gradual loss of performance and then it takes ages to start cos the fuel will be fighting against the restriction

- Moving restriction in the line or in the tank - I won't go down this route till we have exhausted the other options but it is within my relm of experience it's just far more unusual

- failing fuel pump a possibilty but unlikely (if we have to look at above we'll examine that too)

- incorrect float height (ie poor set up on the new carb) I'll discount cos it appears when it runs it runs well and you are happy with it

Off out now but back later today so if you can answer any of the questions I'll continue to help where I can

[ste mk1lx]

is the two way valve for the idle speed boost (the black box on the bulkhead with 2 pipes coming from it) still connected?

[GroovyCarrot]

Well, I've been playing around with it today.. it did the same thing 3 more times, then I revved the engine harshly a few times and it hasn't done it since.. I've driven it for about 45 minutes with no problems at all. I'm hoping that whatever caused it has fixed itself somehow, but I'd better give it a few days running before I declare it a complete success.

In answer to all of your questions:

The box with the vacuum pipes (I assume this is the two way valve? I was never sure what it did..) is still connected, and I've replaced all of the tubes. I've done a vacuum test and it was at the top end of the 'normal' range on my guage (I'll tell you what that is in in/HG or mm/HG if you want, but I'll have to go and find out). I watched the vacuum guage as it started to lose power one time, and it started gradually dropping and then fell off rapidly within about three revolutions, if that's a help.

Plugs wet or dry I'll have to tell you if it does it again, I'm afraid I didn't think to check when it was still doing it.
Fuel pump is mechanical, I did a pressure test on it and it actually seemed a good bit higher than the specifications.. I couldn't see why this would be, but I changed it for a spare one I had in the shed, which seems to work fine.
Fuel filter looks perfectly clean to me, and really hasn't covered many miles anyway. There always seems to be a reasonable flow of fuel through it, even when it's on the verge of cutting out.
Restrictions in the line are perfectly possible, but it seems strange that they'd only become apparent the moment I change the carburettor.
Float height again a possibility, but it really does seem to run perfectly when it goes.

What I'm hoping is that there was just a bit of rubbish that got into the carb and choked things up which shifted when I started revving it.. but like I said, I'll give it a few days worth of testing before I declare it all clear.. driving into town tomorrow first thing in the morning when it's still freezing cold should be a good indication of how well it's doing, anyway.

Well, cheers for all your help, sorry to trouble you with yet more problems

[GroovyCarrot]

Cut out this morning, just before a very busy mini roundabout in rush hour.. got it started eventually, and then cut out again coming into the car park where I had to get a couple of friends to give me a push into a parking bay I checked the spark plugs, and they're black as anything, absolutely caked in carbon, plus there's a great big patch of soot on the tarmac under my exhaust pipe from where I started revving it after I got it going again - never had it that rich before! Strange thing is, if it's running as rich as that it's suprising that it runs so smooth most of the time, and that the vacuum reading is so strong. I've decided to bite the bullet, and my local friendly mechanic is coming round tomorrow afternoon to sort it for me. First time in a year that I've had anyone but an autoelectrician fix my car for me, which is pretty good going considering the amount I've fiddled with it and how little experience I actually have. Still, I'm quite prepared to accept that carburettors are beyond me and I'd rather have a professional get it right than spend months cursing at the damn thing. Here's hoping that he gets it fixed up quickly..

[Tahrey1043]

complete shot in the dark but p'raps your choke cable aint set up right? ie you're on full choke 24/7... would explain the richness!

[GroovyCarrot]

Logical thinking but unfortunately no, it's wide open with the choke control fully in, and tight shut with it fully out.. it's possible that I'm overchoking it, but I run it at a choke setting where it's as open as possible whilst still idling comfortably.. maybe I need to increase the fast idle so it's more stable with the choke further open.. but anyway, the mechanic's booked for tomorrow afternoon, I hereby declare this mess up to him to sort out. I wash my hands of carburettors, I think they're best left to the professionals

[bstardchild]

My money is now on an oversize jet or more likely float height set way too high if the plugs are black and sooty......

Float height would be my favorite as the overfueling would be erratic and uncontrolled

Oversize Jet would be unlikely to result in intermittant engine stopping

A quick call to weber or a search on the web may well reveal the correct jet sizes and float height measurements - if I get chance later I'll have a ethan

[GroovyCarrot]

Mechanic came today and sorted it (hopefully..). Said it was just really badly set up, so he tuned it for me. Strange as the vacuum guage was reading so good originally, now it's just inside the normal range and fluctuating a bit Still, it drives perfectly and I've not had it cutting out yet. Once again, the proof will be in the early morning drive to town..