Back firing and no go T25

Post by **JABMO** » 16 Jul 2012, 19:41

Hello, I really hope you guys can help

I have a T25 1600cc Air cooled camper. Electronic ignition, have changed leads, spark plugs, rotor arm and cap. Also a replacement coil has been fitted. When the engine is hot the camper engine starts to die and back fire and then cuts out. When i wait for 5 minutes I can start her again and she runs for a little while but the same things happens again. Bug Jam in 3 days and the panic has set in. Your help is needed in the most trying of days

Jason and Marie.

Post by **BOXY** » 16 Jul 2012, 21:06

Have you check the fuel filter? £1.50 part, 3 minutes to replace.

Post by **JABMO** » 17 Jul 2012, 05:40

Hi Boxy. No I haven't but checking it this morning cheers.

Post by **JABMO** » 17 Jul 2012, 08:43

Changing the ignition module and have had the carb taken off and being cleaned. Inline fuel filter looks clean and plenty of fuel in there. Running out of parts to change!!

Post by **82JEW75** » 17 Jul 2012, 11:57

Backfiring through carb or exhaust?

Post by **kevtherev** » 17 Jul 2012, 12:12

JABMO wrote:Inline fuel filter looks clean !!

looks are deceiving..
Fuel pump/pushrod fault/worn will also induce a backfire
Backfiring on the overrun is a classic air leak on induction too

Always fuel..spark..timing, on an investigation.

Post by **JABMO** » 17 Jul 2012, 12:52

Thanks Guys, the back fire is from the exhaust. When I get the carb back on tomorrow morning I will show the guy fixing it your comments so we can tackle all areas.

Post by **JABMO** » 18 Jul 2012, 15:25

Finally got her running this morning and been for a longish drive to see if she holds up. Changed the filters and everything else to boot but still did not cure the back fire, after a compresion test it turns out I have lost alot of compression on one cylinder. Therefore its time for an engine overhaul when I return. For now the problem has been cured/masked by advancing the timing slightly. Just needs to hold up for this weekends Bug Jam and then in the shop she goes. Thanks for your help on this.

Post by **steve n liz** » 18 Jul 2012, 17:21

We had a similar fault on our 2l a/c and had it looked at last year at vanfest and the German tuning guys changed the solenoid on one of the twin carbs and its not done it since,hth.

Steve

Post by **82JEW75** » 18 Jul 2012, 18:28

JABMO wrote:Finally got her running this morning and been for a longish drive to see if she holds up. Changed the filters and everything else to boot but still did not cure the back fire, after a compresion test it turns out I have lost alot of compression on one cylinder. Therefore its time for an engine overhaul when I return. For now the problem has been cured/masked by advancing the timing slightly. Just needs to hold up for this weekends Bug Jam and then in the shop she goes. Thanks for your help on this.

Burned exhaust valve, number 3 cylinder by any chance?

Hope you make it there and back under your own power, take it easy.

Full top-end rebuild on a CT (heads, pistons and barrels) is not too expensive, big advantage being that you can use beetle parts.

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Back firing and no go T25

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