rich mixture on a 88 240

Hello

I drive a 1988 240 with the 2.3 carburettor engine.
This week it failed its MoT test because of the exhaust gasses. The CO
reading was too high.
It's been smelling quite petrol-y, so I guess that means it's been running
rich.
I took it to my usual independent Volvo mechanics, and they said they turned
down the fuelling so that the car passed its emissions test, but then in
order to make it run smoothly (especially when cold?) they've turned it back
up. They say that this is simply because it's old.
I used to think these mechanics were marvellous, but now I'm not so sure.
It shouldn't have to run rich all the time, should it? Not just 'becuase
it's an old enigne'? Doesn't this indicate that something else is wrong or
needs looking at? And will this affect my fuel consumption noticeably?

Your comments would be much appreciated.

Thanks

olly

 

How's the compression? If that and the ignition timing are within spec, then
the carburetor shouldn't have to be set rich to make it run smoothly.

 

That's a fact of life on older cars. Many years ago I bought a used 240
Turbo, and it started and ran perfectly when cold. I did a tune up,
changing all the normal tune up parts, as well as setting the slightly
too rich mixture back to spec. The next morning the car started, and
immediately stalled, I restarted 3 times before I could keep it
running. I though about what had changed - and move the idle adjustment
screw back to where it was - and the problem was gone. And this is with
fuel injection - carbs are more prone to these problems. My friend that
runs the Volvo garage tells me that setting the old B21As to spec is a
sure way to make the customer mad at you - he sets them all just rich
enough so there's no running problems. He always keeps them overnight
so he can make one cold start himself to make sure he's got it right.

I would suggest you raise your opinion of your mechanic at least back to
where it was, maybe even a tiny bit higher.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Thanks, that's very reassuring.

I picked it up this morning, and it ran beautifully all the way home. I'll
see what happens tomorrow morning!

will do!

olly

 

If they say that, they obviously haven't done much investigation. 99% likely
your 240 Turbo had a bad control pressure regulator, symptoms of it's
failure fit yours to a T. "It's just old" is simply a lame excuse given by
those unwilling to track down the fault.

 

Mine's not a turbo, it's the 2.3 carburettor engine.
To give them their due, they've known this car for years and years now,
since two owners before me, so I don't think they're being lazy.
I'll see how it starts very soon.....

olly

 

On the 240 turbo, "they" is me. And I have access to the proper fuel
pressure testing gauge, and there was nothing wrong with the control
pressure. And when that control pressure regulator started leaking and
I put in a new one, the situation didn't change. And I've seen this on
literally dozens of K-Jetronic and carbed Volvos. The LH injected cars
seem to be able to compensate better.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

K-Jet is a pain in the ass, I think it's more that the mechanical parts of
it wear when they get old than the engine, finding a good fuel distributor
can be a real hassle though.