View Full Version : TONS of black smoke at idle!!

09-03-08, 08:48
OK, another question;

On my '85, which has been standing for over a year I understand, I have resurrected it to the point of first hint of starter cranking it over :-)

Now; air filter is brand new, throttle body & Airflow meter has been cleaned thoroughly (by me) but still from cold the car starts up with a wisp of black smoke (Which tradition tells me is running too rich) and gets far more dense as she sits idling (we're talking CLOUDS of smoke!).

At first I thought it was probably valve stem seals from sitting, but as its black not blue, I'm tending away from that being the cause and leaning towards either a stuck (open) injector (or cold start injector) or faulty auxiliary air valve (or something else!).

Of course being armed with ONLY the useless Haynes manual; I have NO testing procedures for checking any of the above.

Any ideas, short of my next step, which will be to pull all the injectors for a good cleaning?

I must add too, that the car is possessed as at first (in recent weeks) it'd run for a while (say 10minutes max.) then snuff out, but when I REVERSED the 12v flow to the fuel pump (effectively running it in reverse); it'd start and run smoothly, with no noticeable smoke (of any colour) but die from lack of fuel after 20 seconds or less.

This WEIRD process made me think that reversing the fuel flow MAY have helped clean out the system a tad.

...I have already drained both fuel tanks and both were clean surprisingly. I also have loads of fuel injector cleaner in the tanks, (But not THAT much as to cause the smoke!).


Andi Candoo
29-03-08, 17:13
Have you checked fuel ressure regulator?

If fuel pressure is too high it could cause fuel to dribble out of injectors causing black smoke.

30-03-08, 01:43
Have you checked fuel ressure regulator?

Not yet, as such; I did disconnect the vac line to regulator and noticed a difference in idle but not really smoke output.

Andi Candoo
30-03-08, 10:03
If the regulator is faulty, then disconnecting the vacuume wouldn't make much difference pressurewise, after all, unhooking it will just create a "hole" and make the engine draw more air.

Tell you what, pay my fare to Brisbane and I'll have a look see at it :lol:

I was there 10/11 years ago and stayed in Camp Hill for a bit. Also stayed in Lutwich and Toowong. Visited Stradbroke Island for a couple of days camping.

I loved Brisbane, the river, South Beach, City centre (the Irish pubs) and would often walk from the centre to Toowong. Everyone I met in Australia was just fantasticly friendly :D . I used to work in a local radio station here in Inverness and arranged to meet with the guys at Triple M. What a hoot, some gorgeous birds there too :oops:

If someone offered me to move to Australia I would give up everything in this sh*tty Big Brother/Communist run island and move right away, you guys are sooooo lucky over there.

Anyhoo, how old is your car? Does it have catalytic converter? If so, the oxy sensor could have gone faulty. If this happens, the ecu can pour straight petrol in there. I had that with a Peugeot. Nightmare car :evil:

Post some pics of your engine/car and of course Brisbane :wink:

31-03-08, 00:17
hahaha. Gidday Andi;
lots of bells ringing with your reply; I LIVE not that far from Toowong actually! AND used to live at Camp-Hill!!! SMALL world!!! :D Plus have stayed on Straddie many times.

I actually have two XJ6's; an '80 and the '85.
I'm reasonably convinced that black smoke is just a result of a faulty coolant temp sensor; or at least a significant part of it. Running on full enrichment.

...I thought I DID post up some pics here somewhere...I'll have a look later and post some more :D
Cheers mate!