just broke down :( engine won't run

[stinky]

just broken down; as luck (perhaps) would have it I was nipping back to work and I broke down a few hundred feet from work and was able to park in a side-street.

The engine was running fine but then coughed and the revs died.
It'll start and run fine for 5 seconds or so (sounds smooth) but then the revs drop off and the engine shudders before stopping; no amount of throttle will prevent this.

As I'm at work I don't have any tools with me so I can only do a basic inspection, but there is nothing obvious.
There's fuel in it and when it stops you can smell fuel in the engine bay.
It hasn't overheated and there's no oil/water mix in either the Oil or water.
Battery seems strong and turns engine.
Engine turns over slower but without knowing how I know this it sounds more like the engine is labouring than a flat battery.
It will start but like I say it runs for 5 seconds or so before juddering to a halt.

I'll probably head off home somehow and come back tomorrow with tools and I'll probably check for fuel and try to check the plug leads etc.
BTW it's a 765 2.8v6 (early engine)

Any other recommendations?

I'd really appreciate your help.

[RiPsTa33]

Sounds like a blocked fuel line or a knackered fuel pump

[CTCNetwork]

Hi,

Originally Posted by RiPsTa33

Sounds like a blocked fuel line or a knackered fuel pump

Or fuel pump relay??
Fuel Filter.??

Des. . .

[LankyTim]

All together,

FUEL PUMP RELAY!!!!!!!*















*probably

[rogerthechorister]

When the fuel pump relay went on my 745 she just went off like turning a switch and thereafter did totally sweet fanny adams.

[LankyTim]

Originally Posted by rogerthechorister

When the fuel pump relay went on my 745 she just went off like turning a switch and thereafter did totally sweet fanny adams.

Hummmm..... true!

[stinky]

I'll have a look in the morning, but how can I test the fuel pump relay?
Do you happen to know which connector is which so that I can take it out and try it?

[rogerthechorister]

On my 745 I think it was the back (top) left, and white, but your workshop manual should show.

If you have the fuse numbering correct, pull the relevant fuse and see if anything changes.

Also (after replacing fuse) take off fuel filler cap, turn on ignition and listen. If relay and pump are both good, you should hear it pumping.

If she nearly starts you are getting some fuel lifted, but maybe not enough to run... Is there an inline fuel filter on these? If so, I've done this on Fiats (twin cams of various types) and about 25 different types of BMC A series engine., not sure about Volvos. You need two non-smokers to try the next bit. One of you takes the fuel pipe off the OUTPUT side of the filter - and plugs the end of the fuel pipe. Now if the pump lifts fuel it will squirt out of the filter. Get tin can ready to catch petrol. Other person turns on ignition. Fuel should spurt excitedly out of the filter. Yell at the person to turn off again. No squirt, or a miserable dribble - it's filter (or pump or relay, but if you can hear the pump pumping in the tank, it's probably not the pump).

However, you say that the engine is reluctant to turn and the cranking speed is down? That sounds more like an electrical problem, or a serious mechanical expense.

[stinky]

many thanks for your advice guys.
I had a new fuel filter that I've been meaning to fit so I took the old one off:

First I checked all fuses and they seem OK then I removed all clicking relays except the fuel relay (green on mine); still clicked, removed it: no clicks at all; put it back in and I could hear and feel the fuel relay clicking so I reckon that's OK (although if I fix the car I'll buy a spare).

I took the outlet side of the fuel filter off and cranked it: Lots of fuel pumped out.
I replaced the filter and tried again, same as before: will start and revs about half as good as it should and it sounds OK, no knocking or screeching, no bad smells, but the revs drop off after a few seconds and it shudders and dies.

Took the distributor cap off and rotor arm, both look OK, cleaned them and put them back; no difference.
(Could be the distributor that has failed mechanically though)

I've stopped for lunch now but when I go back I shall check:

Idle control valve
Air Inlet valve/flap
Spark from each plug
Both pumps
Fuel to each injector

What about ballast resistors or whatever?
Any more ideas, what about flywheel sensors etc?

[rogerthechorister]

You now know you have fuel through the fuel filter. What is the next critical point? Is it the injectors? Careful, a high pressure droplet of fuel can be nasty.... but are they clicking correctly? Not sure to check how they are working in detail.

If the car starts, then you have spark at that moment - but have you a spark tester and can you leave it in circuit and see if the spark dies? If you have spark, and it is not dying, it HAS to be either a fuel or brains. Brains depend on their sensors. For example if the AMM is lying and saying "no air" the brains will cut the fuel. If the AMM is saying "loads of air" the brains will increase fueling and the engine may die because it is too rich. You say you have fuel smells, so that seems plausible to me.

If the lambda sensor is reporting wrong, the brains could be wrongly adjusting the mixture.

If the knock sensor is reporting wrong, the brains could be wrongly adjusting timing.

Is it a CAT car? Wouldn't you get similar symptoms if the CAT was heavily blocked?

Can you tow it to a garage with electronic diagnostic stuff for checkiing?