First question - Backfire

[texasuk]

I've just bought an '83 1.9 and while it drives fine at the moment, it has the tendency to backfire (but not loudly, like a women breaking wind) when coasting. Under load it pulls well, although it feels a little 'worn', if that makes sense.
Any ideas of what to look at first? Timing perhaps? Is it a known problem?

Cheers,

[kevtherev]

air leak/weak mixture

[texasuk]

Thanks for the quick answer, but just to verify, do you mean an air leak on the induction side or the exhaust? And a weak mixture can cause a back fire?

[kevtherev]

yes to both

induction side.. could be the vacuum servo pipe off the manifold a vacuum pipe on the back of the carb, the choke pull down diaphragm, manifold gasket.

[fairwynds]

...also worth doing compression tests on all four cylinders at some point.
I had same symptoms and when enging was stripped found a burnt valve. This was probably caused by running with bad timing for extended period... so very important to check as above. FW

[Wolfsburg Willy]

it has the tendency to backfire (but not loudly, like a women breaking wind) when coasting.

If it backfires on over-run it is most probably an air leak. It's also worth checking the dissie for correct centrifugal advance and vacuum advance operation.

[HarryMann]

Yup, weak or retarded.. even a small exhaust leak or non-standard silencer (noisy) can creat popping back on the over-run

So you have it confirmed, 87 of us agree

[kevtherev]

Even the Haynes agrees

[clartsonly]

exhaust blowing... old weak engine is it most definitly a DG and not a DF (like mine) very weak indeed only two hills allowed a month

[texasuk]

Thanks for the suggestions, as soon as I get some time I shall check and let you know if an air leak is what was causing it.

[ghost123uk]

Thanks for the suggestions, as soon as I get some time I shall check and let you know if an air leak is what was causing it.

If it turns out to be an exhaust leak, (very likely), post back on here before rushing into anything

Exhaust jobs on these engines are not for the inexperienced or faint hearted

[kevtherev]

Exhaust jobs on these engines are not for the inexperienced or faint hearted

or Kwik Fit

[ghost123uk]

Exhaust jobs on these engines are not for the inexperienced or faint hearted

or Kwik Fit

[texasuk]

Just thought I would post the answer, which was that the vacuum pipes were slightly loose. Very slightly, a bit of a clean and pressing firmly and the problem disappeared. Cool.

Thanks for the help.