NEW MEMBER / OWNER NEEDING ADVICE!! BACKFIRING ONCE WARM..

[thorby]

Hi, new to forum and just bought a 1.9 Petrol Watercooled T25 (1983). Wondering if anyone has any ideas as to how we might go about solving van's problems?? We knew when we bought it very cheap that it was a bit broken, but having had a few beetles in the past thought that it might just need some carb tinkering and that we'd grabbed ourselves a bargain. However..... (I'm going to be as descriptive as possible)
First issue was that the van would start, but then cut out once warmed up. Previous owners couldn't then get it restarted, they said, until it cooled down. We had a vw friend come and look it over and he tinkered, got it running better, turned a springround that was apparently upside down and diagnosed air leaks and the need to replace a couple of the carb gaskets (apologies if my descriptions don't sound that technical)! Van then would restart after cutting out.
We took it to a garage for an MOT and rather than us sorting out the carb, asked them to get it running for us. Picked it up last night and all sounded really healthy. The van drove well for about 6 miles, through town and on the motorway. However, after the motorway run, it started cutting out at every junction and backfiring like mad. Obviously, the garage are going to have another look at it, but wondered if this rang any bells with anyone?
We did put some petrol in just before going on the motorway, and it has been running on pretty old petrol so it might be that its muck in the fuel tank, but we suspect something a bit more serious..... We had it running today and after about 10 minutes, same thing, idling became a bit erratic, when I revved it backfired, then got worse til it cut out again.
Don't mind bad news, in fact, prepare us for the worst and then we might end up pleasantly surprised! Any help very gratefully received.

[kevtherev]

Just be sure the timing is set properly and plugs/leads are new

But I would say your on the right lines with fuelling.
A back firing engine is a sure sign of weak mixture, blocked jet, clogged fuel ilter, air leaks. To name a few

[thorby]

Brilliant! Glad we're on the right track. Previous owners suggested engine might be dying - any chance it could be this? Hopefully a bit more work and we can plan our first trip! Thanks loads for help.

[R0B]

just so you know the fuel filter is just after the tank.

[jason k]

could also be an overheating coil,