Intermittant backfiring 1988 1.9 petrol

[kevtherev]

Intermittent issues are generally electrical connections. Imo
Connections degrade and corrode
I would clean all connections to your coil and spark control.

When the garage say they have checked components, I assume they provide the data from the test?

[CovKid]

Fuel line draining back overnight? Weak fuel pump? You always need a considerably richer mix from cold. The fact you couldn't start it at all is telling. Next time it won't start, try tipping an egg cup full of fuel down carb throat (pull off rubber elbow). See if it'll start then. If it does, its fuel related, if it doesn't its lack of spark. Could be that. or ineffective choke.

[triumph2.5pi]

Thanks again for the tips, I'll try those
Didn't get any diagnostics from the garage, no. I didn't realise they could supply that to be honest, but I'll know for next time.
I don't have great confidence in the garage...They are T25 specialists but I've noticed their attention to detail is sometimes lacking - had a whole new stainless exhaust fitted and it knocked when I picked it up, leisure battery not reconnected after they been working on the van...and other things like that, that make me wonder what their standard of their work is like that I'm not fully able to judge.
I'm kinda caught between a rock and a hard place as they're the only T25 specialists within reach that I know about - I've asked more than once on the forum for any other recommendations/suggestions but drawn a blank...So it's either stick with them or take it to a "normal" garage which is again an unknown. So I've stuck with the devil I know so far...
I appreciate your help anyway. I'll clean the connections and try the egg cup trick if it doesn't start again

[kevtherev]

There is another alternative.
That is to learn how to do things yourself.

But maybe you're physically challenged or summat?

[Ralf85]

Put your locality etc in your profile details and then perhaps somebody can suggest a localish reliable garage to you.

[CovKid]

Poorly fitted exhaust manifold somewhere can cause backfiring when descending hills/inclines - another possibility.

[triumph2.5pi]

Thanks again all.
The van's going in for a new clutch today and I'm going to ask them to clean the connections as suggested by Kev.
I've put my locality in my profile now, so if anyone can recommend, or even suggest a garage within striking distance that would be much appreciated.

[triumph2.5pi]

And the culprit was...the coil. It took an age to diagnose as the fault was so intermittent and of course the van ran faultlessly every time I took it to the garage....

The symptoms were only present when it was very damp, or it had been raining for an extended period. Now, with an original engine, 135k on the clock and a new coil fitted, it's running sweet as a nut, all the time! It's nice not to have the embarrassment of a backfiring van any more!

Thanks again all for your input, much appreciated

[kevtherev]

Thanks for the update.