Poorly Engine

[hartge bob]

Cruising down the motorway this morning, happily doing a steady 75-80 all of a sudden lots of stuttering from the engine.

Cleared itself after a few seconds only to happen again a couple of minutes later.

Finally lots of stuttering, not clearing itself, lifted throttle - same, gave more throttle - same.

I dipped the clutch and the revs died right off to the point of stalling. Clutch back up got it running again. OK again for a minute or two then a large backfire with a small puff of black smoke and a very spluttery engine. But no clouds of smoke or anything.

Luckily it was quiet and I was near a slip road. Managed to coast up the slip road and get into a handy layby.

On trying to restart - nothing. Turned over fine but wouldn't fire.

Recovery man came out, all he could confirm was there was a good spark at the plugs. Recovered home on a flatbed.

Now sat on the drive, turns over no problem but won't even try to fire.

How much trouble am I in?

Any suggestions, pointers or donations gratefully received.

 

[wedgepilot]

Sorry to hear that. [] If there's a spark (well, 4 four sparks hopefully) it could be lack of petrol. I'm thinking fuel pump, relay.....something like that?

 

[937carrera]

Sounds like fuel to me too, some suggestions to try and diagnose the fault

Check fuel pump fuse (obvious, but unlikely)
Check DME relay / fuel pump relay.....they should click when ignition is turned on
Get down on the floor , ear close to fuel pump, while someone else switches the ignition on, you should here a short buzzing, which will start again while the engine is cranked over.
If the pump isn't working, check for 12 V on the supply side with a meter / neon test light.
Failing that remove the battery & with some spare wire directly connect positive and earth from the battery to the fuel pump. If it runs the fault is elsewhere, if it doesn't you need a new fuel pump.

 

[Fen]

I've had a fuel pump relay fail - it's a Vauxhall part and the AA generally carry them, but you're at home. Worth a pop for all it costs maybe.

The DME relay would kill the spark rather than the fuel, surely?

 

[937carrera]

ORIGINAL: Fen

The DME relay would kill the spark rather than the fuel, surely?

Quite true, but I believe the DME relay acts as a trigger for the fuel pump relay. "I may be wrong"

 

[Guest]

It may be your air flow meter. Is there a strong smell of petrol? I had the same problem and got it recalibrated and then ran like a dream.

The air flow meter is what gauges how much air is mixed with the fuel to get the optimum "explosion" during combustion.

On an S2, it looks like this.



Hope this helps.

 

[Diver944]

I would plump for the DME relay also.

When mine went it just would not fire. Plug out showed a healthy spark but no fuel being squirted into the cylinder.

Try starting it and then pulling out a plug. If its dry and there is no petrol smell then you have no fuel being squirted in there.

There is a great checklist to test the DME relay at http://www.clarks-garage.com/ also an emergency get you home fix until you buy a new relay (under £20 from OPC)