'89' 740 GLE AGAIN!

I understand your logic, but in my experience, when I have illiminated everything else I have simple discovered the limits to my own ignorance - there is still plenty of other stuff that I haven't thought of yet.

Fuel control units seldom go wrong, and cost, IIRC, a couple of hundred pounds or so for a new one. But I got a secondhand one off the shelf at a local breakes for 20 quid, so it's not all bad news. Go through the Yellow Pages; some breakers specialise in Volvo parts and can be quite helpful.

But you could try adjusting the mixture. Did the workshop measure the exhaust gases? Have a look at Fig. 6.4 here:

The Idle Mixture Adjustment Screw is located inside the Airflow Meter, but can be accessed via a little hole in the top. Long thin screwdriver needed. You could try tweeking it a quarter of a turn at a time to see if it makes a difference. Keep count of the turns so you can put it back to how it was. An exhaust gas analyser helps too, though if you are careful you can do it by ear.

Okey Dokey.

Here is a list of what the nice man at Carb and Injection tested and carried out.:

1. Checked air filter and air intakes.
2. Checked all vacuum pipes and connections.
3. Checked all fuel lines and fittings
4. Checked fuel line pressures. Main lines and controlled side.
5. Checked co levels, cam timing and ignition timing
6. Checked coil, leads, distributor and plugs.
7. Checked injectors (Although they seldom cause a problem)
8. Checked all pipework and electrical connections to ALL valves, regulators and injectors.
9. Checked for blockage in exhaust.
10. Replaced warm up regulator. (which was indeed buggered)
11. Refit new copper washers and 'o' rings where necessary.

The car was on a dyno tester most of the time and when he replaced the regulator he reset the CO levels.

It seems to be a fairly conclusive looking list and being as they checked everything barring the fuel control unit and bearing in mind that the warm up regulator was full of crap. Natural progression leads me to the control unit being dirty or faulty.

I know the fuel distributor can be removed from it but how easy would it be to flush out the rest of the unit? Or is that a big no, no?

I've never taken one apart, but I know there's a bunch of very fragile diaphragms inside it. You can get an idea of how clean it is by removing it from the air flow meter (3 screws) and taking the control piston out. This piston is precision machined to match that control unit, and can fall out the bottom of the unit as you remove it. If it does, then it's not precision machined enough any more, and you'll need to buy a new or rebuilt unit. The only thing that kills them is bad gas, and unfortunately, it sounds like that may have happened to your car.

IF the fuel line pressures check out OK, AND the CO levels are OK, I reckon this must cover the functioning of the fuel distributor.

On the other hand, if EVERYTHING checks out OK, then the engine should run properly. The fact that yours doesn't is a deepening mystery.

The crap in the regulator prompts the question about how it got there. Is the fuel filter good? If there is more crap in the system, perhaps partially blocking a fuel line, then it may be restricting maximum flow of fuel, leading to fuel starvation at higher revs and under load. This seems like clutching at straws, but you seem to have eliminated so much else.

I think the best you can do in this regard is to disconnect all the fuel lines, take them off the car and blow them through with a high pressure air line. If you are suggesting dismantling the fuel distributor, the early Haynes manual (black cover) describes removing the control plunger (the bit the meters the fuel) and the control pressure regulator to clean them, but warns not to attempt further dismantling. Normally I take this sort of advice from Haynes as a challenge, but in this case I think I'd recommend against it - the internals are fairly high precision engineering. Locate a secondhand unit first, before you risk damaging the one you've got.

Thanks for all your help guys. You have been a HUGE help.

Now I am in the market for a fuel control unit for an '89' 740 gle manual the one with the b230e 'k' jet red block motor.

Anyone happen to have a spare kicking around in a box in their garage?

Thought I would ask.

Isn't this the same unit as any other non-turbo K-jet Volvo uses? Shouldn't be too hard to find, all the old 240's used them here.