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2.5l petrol seems to be misfiring

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Hi All,

I'll explain the situation and would appreciate any help in identifying areas to check for a resolution

During the cold spell we've had I posted this topic and came to the conclusion that the carb was freezing up.

Now the weather is a bit better and today was a dry clear day and not too cold. I've also just changed the spark plugs and coil.

I needed to go out in the 90 and it seemed to start up ok and went ok, a bit hesitant but figured it was due to it standing all week and needing to warm up. At normal operating temp it seemed to be misfiring a bit (that could be a mis diagnosis) and seemed to be missing a beat quite frequently. The other behaviour it exhibited was a tendency to feel like it was lacking power as I went along. It seemed to start to accelerate and then drop off momentarily before kicking back in again. It feels like it's maybe a lack of fuel issue almost as if it has air getting into the system and making the acceleration peak and trough. During the times of low power it makes a putt putt noise.

The strange bit occured half way on my outbound journey after a period of a couple of miles at 50 mph followed by a slow crawl through a line of raffic to a roundabout. After the the roundabout the acceleration was smooth and all the power was back. Then after stopping at the tip and starting to head back the lumpy power syndrom returned and stayed all day.

If anyone has had these symptoms or can shed any light on areas to check I would be grateful as it gets a bit silly when trying to pull away from a junction and most of the power dies off and I have to dip the clutch to gets the revs up enough.



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Hi there,

I run a 2.25 petrol 90 that I has also had weird running problems/lacking power in recent years.

I originally thought it was due to dirt in the carburettor from wading through deep muddy water. However it wasn't until I had replced the coil (Paddocks cheapest) and replaced the distributor with an electronic Lucas one did it start running properly again.

The coil was a guess, hence buying the cheapest one however this distributor was a different matter. While changing the points I noticed there was lateral play in the shaft; dirty water has entered the distributor from wading and worn the bearings...

Hope this is helpful


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Thanks for your replies.

I have an electronic dizzy I have yet to get around to fitting so I'll give that a go as well.

One thing I did notice was that when it was running relatively well it was making a bit of a tappet racket and thats another job on the list.

I'll be having a look at my dizzy to see if there is anything amiss

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After fitting the electronic dizzy I wished I'd done it years ago.

My engine also taps a bit but then as far as I believe the engine is orignal and I'm using unleaded petrol so I'm expecting wear in the valve seats. It's probably about time I looked at the valve clearences again.

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Well what an amazing difference a dizzy makes.

I managed to get time yesterday to change my dizzy to the electronic one I had been given by a very generous forum member.

I guess I shouldn't be too suprised that the dizzy was on it's way out when Iwent to take the cap off and one of the springs holding it pinged off and the cap was a bit skewed.

After taking out the old one I looked inside the cap and noticed the plastic holding in the metal inserts was all chipped and I guess thats not particularly good.

I also managed to use use an old timing strobe light to tune the engine so it ran a bit better.

I managed to take it tonight to see if there was any difference and managed to easily roll along at 30mph in fourth which is nearly unheard of previously. I also found a massive improvement in hill starts and motorway performance and generally a pleasure to drive again.

The only problem now is that the radio suffers from interferrence from the new dizzy.

Thanks for all your help with this one.


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