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Car slowly looses engine power and then cuts out

Hi

I have an odd problem with my aging Cavalier L petrol 1600 engine (1990 with 170k on the clock). I am looking for a simple low cost solution simply because the car is not worth much anyway. The problem has got worse over a month or so.

Five-ten minutes after a cold start I will be driving along quite happily when I notice the engine power is slowly dropping off. The radio starts cutting out too. At first I notice lumpy acceleration - say between 30 and 50 mph in 3rd gear it seems like the engine is misfiring and then as speed slowly increases suddenly it kicks in and you can feel the car pull away properly. A few minutes later it starts to feel like a lawnmower engine under the bonnet. It gets worse until I slow or stop. Then the engine will just cut out. Immediate restarts fail. However if I wait 2-3 minutes it starts up perfectly (radio is OK too) and we shoot off as though nothing happened - until the cycle starts again about 5 minutes later. I believe the radio is cutting out because the voltage it's getting has dropped to a cut off level. The radio cutting out may be a red herring but I mention anyway in case it helps diagnosis.

To preempt some questions...the alternator is charging the battery fine. The battery is only a couple of months old. The battery terminals read 13+ volts when ticking over. No problems starting from cold. It had a vacuum problem (something to do with the carburetor) which was resolved with a replacement length of tube a couple of months ago. I have given the tubes in that area another quick check and they *appear* to be OK. I have not started using different fuel recently.

Many thanks!

Paul, Haynes manual at the ready.

Reply to
Paul Baker
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2-3 minutes it starts up

Ignition coil? My old Sierra did this and it baffled me for ages, until it finally died completely and I worked out there was no HT. It used to "recover" after 3-5 minutes, just as yours does. Doesn't explain the radio though.

Dan

Reply to
Dan Post

Is the period of coughing and spluttering before it conks getting shorter? Mine did. Something to do with the coil windings breaking up as the coil gets warm, and then "re-making" when it cools down. After a while, it breaks up sooner, then eventually, dies completely.

Dan

Reply to
Dan Post

Where r u Paul...... North ? May sound stupid..... but it DOES happen..... Carb icing !!! Check if the hot air intake to the air breather is OK.... Cavaliers did have this prob... Cheap solution...... Self taper through the flap and tape off the intake air from the outside and then it has to draw the air from the exhaust manifold heater. The cavalier has a vacuum operated flap which failed.

JK

Reply to
JK

Thanks for the suggestion JK. I am in Berkshire and haven't noticed the problem get worse with lower temperatures, however I will bear your suggestion in mind.

Thanks again

Paul

Reply to
Paul Baker

Could be one of many things.But definitely fuel or ignition. Possible fuel starvation? - the carb float bowl will empty,due to either a faulty fuel pump or blocked pipe/filter.Once it has stopped, it'll give the carb float bowl a chance to refill, then the process starts over again.If it'll tick over for ages and not have a problem, then when it is revved for a while it cuts out, then that may be a cause. Worn carburettor.I had this on a MK1 Cavalier.Ran fine up to 40mph, but after that it ran terribly, until the engine would just die.Eventually traced to a well worn carburettor,where the spindles going through the carb body were worn, allowing air through, and then weaking the mixture enough to stall the engine at high speeds. As has been mentioned, possible coil fault, and could even be HT leads breaking down.Have a look under the bonnet with the engine running on a damp night.If there are any visible sparks,change the leads. Also, maybe something really daft? Loose earth lead? Loose battery connections? Alan.

Reply to
A.lee

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