Overfuelling Issue

Guest · Mar 12, 2009

Gents
A friend has an '81 924 Auto and she is putting out clouds of black smoke, starting badly and really sore on fuel. He left her to a garage who are trying to sort it out. I have 2 s**ters that I use for parts. The garage doing the work asked me for the fuel metering head off one. I asked why and they said that when they set the fuel up it goes good for a while but then goes out of adjustment again.

I told them to look at the cold start injector and make sure its not leaking. They said they disconnected the plug off it and it made no difference. I take it they didnt isolate the fuel. I asked them to check all the pipes to the inlet manifold and metering head for air leaks. The thermoswitch might be another culprit.

Have any of you guys had a similar issue and what was the outcome..? .. Maybe Ive missed somthing..

Cheers Lads

TimEwins · Mar 19, 2009

I once had problems with my 924 along these lines. A shocking 17mpg and CO2% that wouldn't stay put

I changed lots of things to try and fix it (I shoud have had it diagnosed ... but there you go)

I checked the 5th Injector - Problem remained
I changed all the injectors - Problem remained
I changed the Auxillary Air Regulator - Problem remained
I changed he Control Pressure Regulator - Problem FIXED

The Control Pressure Regulator is a square assembly bolted onto the inlet manifold. Its function is to control the mixture going into the engine during warm up.

When the car starts cold, it adjusts the pressure applied to the air valve/plate and richens the mixture. As the engine heats up, the valve closes up automatically, returning the mixture to normal. As a precaution there is a bi-metallic strip in there that closes the valve after a few minutes (15?). The bi-metallic strip in mine was broken. Hence the valve was opening and closing with engine temperature and never fully shutting off.

After fixing this I returned to my economic 25mpg, and no oild residue in the tailpipe due to excess fuel being put into the engine

Just my experience, hope it helps

Regards

Tim

Guest · Mar 20, 2009

The car is now running sweet no problem. As a precaution both the Control Pressure Regulator and Cold Start Valve were changed for a start. The car was set up on the CO and then run for half the day on garage type errands... She ran great.

I told the guys in the garage to change the items individually but they changed both at the same time [

] Now its not clear what sorted out the car....!

Thanks Tim for that wee bit of advice.......! Another one back on the road where it belongs [

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