Recently replaced:
Distributer Cap
HT Lead
Ignition Coil & module
Spark plugs
Fuel Pump
Air Filter / Oil
Rotor
Rebuilt Carb
New Exhaust
Checked for Air Leaks but nothing came to attention. Recently changed the Exhaust system with new gaskets etc. I’ve got a new complete Distributer in the mail with hall sender & vac advance unit but not 100% this is the issue. Thinking timing or fuel related? (don’t have access to a Timing Light but I’m sure garages near do). Any help much appreciated. I’m living in Central Portugal so parts take a awhile to arrive.
What was the original problem, did any of those changes make a difference ?
Who rebuilt the carb - was it a full refurb, or just a strip down and rebuild with existing components / gaskets
You certainly need to check the engine timing. I would also run the engine with the air filter off so you can see if the popping is a backfire in the carb or not
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
Yeah, a lot of the bits that got changed were long overdue anyway. Originally it would struggle to start and hold idle with good amounts of lag in acceleration and no power. The old HT Leads were in bad condition along with dizzy cap and the new ignition coil helped with startup. So all the new bits have helped get to this point.
I rebuilt the carb myself following instructions from 'James Akers' on youtube - https://www.youtube.com/watch?v=amnqCUSTnUw" onclick="window.open(this.href);return false; replacing gaskets and other parts that were old - rebuild kit from JK.
Ran the engine without filter and pretty sure coming from exhaust. would a small gap where the exhaust connects to the engine cause this type of backfire?
From the description of the initial problem I suggest you get a compression test done, but I suggest you check the tappet clearances first. Do a search or read the Wiki if you need instructions
I have a CU which exhibits similar problems and there's definitely a compression/hydraulic tappet issue. May be the same, maybe not.
I don't know what you mean by a small gap on the exhaust, but a gasket leak or small hole in the exhaust is unlikely to be the cause of the symptoms yu describe
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine
Had a similar issue with my bus (DG Motor). Sounded like a cannon going off when it backfired. Fine on tick over most of the time. Traced it to a poor connection in multi plug that goes into distributor from ignition amplifier. Pulled the plug out and one wire had snapped inside the plug itself.It was just sitting there making contact most of the time. May not be the same problem as you are having but worth a look as old wiring will become brittle. I replaced the complete loom and it has been spot on ever since.
1984 1.9 DG Caravelle
1984 Caravelle 1.9 DG 34 DAT
2002 Audi TT 225 BAM.
Thanks 937Carrera: Checked the tappets and clearance all seemed ok. Compression test will be needed next, unfortunately don't have the tester. One thing I noticed when the Rocket covers were off was when I rotated the pulley there was an audible what sounded like a 'leak' of air coming from Cylinder 3, which I guess is what a compression test would reveal? Also when running the engine after, the backfire sounded like it was happening towards Cylinder 3, would this make sense?
Cheers hubcap61: Gone over the wiring already but wouldn't hurt to double/triple check, the wiring/connections on the multi plug to the hall sender look solid.
Something like this should do the job and you'll have the tool for less than it will cost to have a test carried out, assuming you can get it to your place.
There's always air moving around, but all the cylinders work the same