MOT Fail Emissions Advice

[YellowDaisy90]

My 1990 1.9 petrol T25 failed it's MOT on emissions

Exhaust emissions hydrocarbons content excessive

Reading was 1914ppm the limit is 1200

Any ideas how I can fix this? I've done fresh oil, new oil filter, air filter and spark plugs.

How do I adjust the mixture, I can't even find the screw

Any help would be much appreciated

[TONYT25T25]

Mixture screw location depends on what type of carb you have, if doing it yourself you need a tester, have you checked the rubber pipe from crankase tower to carb, they sometimes get gunged up or collapse. Also taking the van for a good run prior to MOT is also suggested.

[YellowDaisy90]

That pipe was all collapsed! Ordered a new one. Thanks for that

[TONYT25T25]

Hope it helps.

[Aidan]

very often on a 1.9 petrol engine carb 2E3 if CO is good but HC is high it is caused initially by a leaky perforated vacuum hose from the intake manifold to the front to back brake vacuum circuit - air is being sucked in through the wall of the hose, causing the left side of engine to run weak, so someone has adjusted up the carb to get co right (only having a basic co tester maybe) and now the right side is running a bit rich and so you have products of unburnt combustion in the exhaust showing as high HC. If this is the case replacing the flex hose and adjusting the carb back a bit should result in balance acceptable for test.
ymmv

[YellowDaisy90]

Is that the hose mentioned above? I'm very new to t25s so don't really know what I'm doing at the moment.

It does sound like it could be that maybe, I don't know what to check/where to look

[YellowDaisy90]

---

CO was 00.19%

HC was 1914ppm 

Any ideas could be causing high hydrocarbons 
 

[THE KESZTHELY KID]

Dunno if this will help,

When emissions testing first became part of the annual MOT my trusty Amanda , (A 547 LTA where are you now?), also failed on the Hydrocarbons.

The MOT tester allowed me to take Amanda along the M62 for a sympathetic 'thrashing'. When retesting the emissions the Hydrocarbons had dropped down to a decent level and passed. YMMV  

[SurfT25]

I have an old colour tune.
For some reason image wont come up, so will try to discribe the kit.
You detach a sparkplug, attach a replica plug with plastic suround. Put the tube with a mirror at the end over spark device attach a lead into tube then reatach lead from distributer.
Start engine then adjust carb fuel intake until you see blue flame, via mirror. This should give your carb/engine a good tuning.
I always gave mine a good run around just before mot as afore mentioned. ( registerd historic now )

Best to put your bus's age,engine type and style at the base of your page so we know how to answer your questions