my M.O.T. is due soon and i am concerned about the black smoke, i have changed filters and oil als added asta 2000 to oil and diesel wich has improved it my townie is a 92 turbo diesel 2.0 litre. Has anyone had a fail due to this problem, which from viewing the BOK is common.. Any comments / advice?
- (#2147) Ron, 7 Feb 02

Go to your local diesel specialist, and have the pump adjusted to pass levels. Shouldn't cost more than £20-30.
I presume you've changes fuel and air filters, the only other thing to try is a bottle of injector cleaner - (#2149) david miller, 7 Feb 02

I guess a lot of us are heading for our first MOT. A reliable mechanic alerted me that whereas most MOT testers will adjust the mixture on a carburettor to get the emissions right, they will often simply fail a diesel - possibly because they don't know what to adjust.
On the 2C-TD the basic "MOT" adjustment, I'm told, is the "maximum fuel screw". See the diagram from the link on townace.com - faults - smoke black (excess fuel). It is at the end of the fuel pump nearest the back of the vehicle and to adjust it your (short) screwdriver is pointing towards the front of the vehicle. There is a locknut to undo.
I have adjusted mine several times, even a quarter of a turn has a noticeable effect and care is needed. Point it out to your MOT tester. If he doesn't want to know, try another one! - (#2161) Dave Mason, 8 Feb 02

For the "free- acceleration " test that's done, you're probably better adjusting the "smoke screw" on the top of the pump ( allen screw and locknut) It won't affect fuelling on boost or under load - (#2162) david miller, 8 Feb 02

The allen screw on top of the fuel pump is temptingly easy but:
1. its cam action means it can be turned to the point where it's having the opposite effect to what you expect - worth taking the top off to see how it works first, and more to the point...
2. it has effect whilst idling or in low-speed cruise (say under 30mph) but has no effect once pressure from the turbo begins to force the diaphragm down - which is why I thought it would not affect the MOT emissions test which runs a diesel at something like 4,500rpm for several seconds and would surely produce turbo pressure.
The maximum fuel screw at the rear of the pump, on the other hand has effect while idling and throughout the power range.
Have I missed something? - (#2187) Dave Mason, 10 Feb 02

the maximum fuel screw is a rather critical adjustment- your quarter turn could rob the engine of much power. I've a boost guage on mine, and on a free-acceleration run, don't see more than a pound or two of boost. no load on the engine to create gas... from my testing, the diaphragm only pulls away from the top stop after a few psi. Rotating the diaphragm and pin slightly is another option, it's a finer adjustment then the fuel screw. - (#2197) david miller, 11 Feb 02

What you say all makes sense, thanks David. I wasn't wanting to argue, just wondering why your advice differs from my neighbour's.
I agree the max fuel screw is tricky to adjust finely. I use a long screwdriver bit with several layers of masking tape wrapped round it and lines marked on the tape so I can see how much I've turned it. By dropping the kickdown cable out of the way a bit I can hold this tool in the screw with one hand and slacken its locking nut with a spanner in the other.
Faced with an MOT fail one of these adjustments might save the day for someone when getting the pump fully set up may not be an immediate option. - (#2200) Dave Mason, 11 Feb 02

Ho ho
i just had this problem in scotland when i discovered my MOT had lapsed! oops. Took it to the local garage who did a good job but had to fil it on the smoke. Remembered a BOK strand from last year where Dave Miller advised a clockwise turn of the 'smoke screw' (is it the "preload"?) of a 6th of a turn. Marked the allen screw before turning it and it did the trick. Legal limit is 3.00-m(-1) mine was 3.4. After adjusting was 1.3 and visibly much less smoke. performance doesn't seem to have suffered. So why do so many owners complain of smoke if it is so easy to correct? is there a drawback to this easy operation?
mark - (#2251) Mark Adams, 17 Feb 02

No real drawback, as long as you don't get it badly wrong. People generally consider diesel pumps a black art, they'd strip a carb, but haven't a clue about pumps... - (#2254) david miller, 18 Feb 02

thanks to the advice on this great site , i have had my fuel pump adjusted today by a very helpful diesel service centre in newcastle and they tested the emmissions to pass level for only £26...and offered to beef it up again at no charge after the mot...!!now clean and runs like a dream . havent even noticed any loss of power, still quite pokey for a townie

- (#2858) Ron Coe, 8 May 02

hi ronnie

mine is in need of that kind of attention,black smoke etc, have just been charged £153 for servicing my injectors and garage thinks now i need a new pump.But i think not thanks to this fine site. is that newcastle upon tyne or newcastle under lyme in staffordshire?

- (#3263) henry, 7 Jun 02

Urgent notice for all who have smokey exhaust.

Having spent a little time talking to my local Toyota Showroom in Yeovil, they recommended that i go and see a garage called LEC and a diesel mechanic. Originally diagnosed by Toyota aas either leaky injectors, fuel pump problem etc etc.

On most of our Townaces / Liteaces which have been imported they are fitted with EGR - Exhaust Gas Recycler. In Japan the limits of emissions are a lot lower than here and this piece of equipment recycles the burnt exhaust fumes.
this therefore cloggs up the inlet manifold leading to starvation of the inlet of air.
This then puts more fuel into the engine to compensate at low RPM and therefore leads to unburnt fuel in tye exhaust system - BLACK SMOKE and increases emissions.
A simple cure - disconnect the EGR pipeline to the inlet manifold and block it off using a clip or tiewrap. It does not effect the system, and will give you better fuel consumption also.
To clear the black smoke, whilst in park or neutral, lift up the seat and continually rev the engine by hand to approx 5000rpm and let go - you will see a cloud of black smoke comming out of exhaust but will eventually die down after about 10 good thrashes.
This i did with mine - no more black smoke, increases acceleration and better fuel consumption - all for the cost of a beer to the mechanic.

- (#3274) Andy Stancliffe, 8 Jun 02

If the EGR system is really bad, the inlet manifold may have to be removed to clean the deposits out- it's a common problem with VW TDI's.

- (#3275) david miller, 8 Jun 02

ok andy good advice

mentioned it to my diesel service centre and they said the same thing. But one thing they did say was,that if the pipe is there and conected it should remain so for MOT reasons, so what they did was put a ball bearing in the pipe and conected it back up.

- (#3379) henry, 16 Jun 02