Stuttering

[RedBarron]

Hi Guys,

as a simple sanity check, I'm about to pull the plugs out of my '67 912. I start the car up fine and it idles as normal, but when accelerating from 1500-3000 rpm it is stuttering and I seem to be down on power. I've checked the points and leads, the car was serviced about 4 weeks ago and I've put about 500 miles on it since then. I don't think it's the carbs, but suspect that having been caught in an hour long traffic jam on Saturday that I may have fouled the plugs. Is this a resonable assumption?

Any suggestions?

Thanks,

David.

[Gary71]

Hi David,

Is it taking out all four or just two cylinders? As your problem is while accelerating I would suspect fuel rather than spark.

Possibly a blocked main jet or ineffective accelerator pump on one of the carbs if it's just one bank. (edit: do they have one carb beetle style or two )

No harm done pulling the plugs out and checking though, along with the points and HT leads. Always start with ignition system as the Haynes manual used to say

[Barry]

Hi David: do your carbs have a fuel filter ahead of them: there's a chance that some muck may have got in. I have to say though, that I'm not familiar with your carbs, so can't suggest where to look I'm afraid. I'd have thought that a) You wouldn't really expect to foul plugs really on that engine and b) If they had fouled, I would have expected them to clear on the next decent run.

You say you've checked the points: if you hadn't said that, I would have suggested these. They definitey haven't closed up? Sometimes as the revs come up, a tight contact gap will open a fraction, and the running will improve. Also IF you've got a condensor, worth just checking this: either by looking for arcing (bad) or by using the ohm-meter. (Disconnect the condensor, put the ohm-meter to ohms, put across condensor: quickly swap the meter leads over and re-apply: the meter should give a little 'kick' showing that the condensor is holding a charge).

After fuel blockage, points and condensor, I'd be tempted to go through the whole of the ignition: just on the basis that this is the area most likely to change suddening, rather than a gradual declining in perfomance. Obviously it's worth doing a quick muppet check as well: correct fuel, no spanners/beer cans/rats etc in engine bay .

HTH, and be interested to see what you find .

[Barry]

Gary: you've done it AGAIN!! I must type faster: each time I do a reply, I post to see that you've beaten me .

[Gary71]

As long as the answers (roughly!) stack up it 's OK!

[RedBarron]

Thanks Gents,

Gonna pull the plugs tonight and check the fuel filters. Had a problem in the past with the condenser so I might check that too. I'll double check the point gap while I'm at it. Let you know how I get on....

D.

[Bertroex]

Gary: you've done it AGAIN!! I must type faster: each time I do a reply, I post to see that you've beaten me .

Miauw!




best regards


Bert

[lewis]

I had exactly the same thing a couple of weeks ago, car would run sweet then, try and accelerate and the stutter appeared Checked the carbs and the electrics no joy. I have a glass filter and that seemed ok full of fuel and clean??? I then decided to check the fuel lines back to the tank, after taking off the fuel line at the tank end the fuel just dribbled out, anyway I am rambling, turned out that the tank connector has a fine mess filter in the tank which was filthy, cleaned everything up and bingo running like a dream again.

lewis

[RedBarron]

Well gents,

As it turns out it was a fuel fouled plug, I got Chris Turner to take a look at it and it was indeed running on 3 cylinders, we switched the soaked plug for a new one and I'm back in business!

Thanks for all the suggestions.

David.

[Barry]

Fantastic: the one and only thing I said it probably wasn't .

Oh well: did you establish why it had happened? Did Chris think it was just down to traffic?

[RedBarron]

Chris said the traffic 'may' have been the cause, but said he would reserve judgement until we were sure it doesn't recur which could be a whole other issue instead.

Drove 50 miles down to a business meeting this morning in Surrey and she didn't miss a beat. So, hopefully the traffic situation doesn't happen again.

D.

[Barry]

See how it goes then, by the sound of it: trouble with Surrey is I'd imagine you'll have to wait for months to find some more traffic to test it with .