1990 Sierra 1.8 CVH

sticky choke mechanism perhaps

These are the only CVH to have a fuel regulator / call it what you will mounted on the inner wing right by the carb, and are often the cause of fuel delivery problems.

Should be pretty easy to determine if the float bowl is empty which is causing your prolonged cranking..

Tim.

what about a squeezy bottle of petrol, before the first start of the day attach a fuel tube to the carb fuel inlet and give it a squirt, it will be obvious if fuel is going in, if it then starts instantly you are on the right track.

I had a similar problem with my Sierra when it would occasionally be difficult to start (but it was 15+ years ago) and that was due to the flywheel sensor bracket being broken. Sometimes the sensor was hanging close enough to allow it to start and sometimes not!

peter

Interesting you should mention the crank position sensor as the way it turns over without firing is precisely like a 1.8 CVH with the sensor disconnected. However, that wouldn't explain why it only does it after a few days standing. Thanks for all the other suggestions too. I'm going to check out the auto choke first and after that the fuel regulator etc.

Mark

Started it today for first time in two weeks and was just as it used to be. Auto choke was woking ok in this cold weather as far as I could tell. Certainly it was keeping revs up to about 1100rpm, so I presume if "pull down" is working then its also throttling off the air intake as it should?

Perhaps this was just one of those odd things that happens for a while then never heard of again. First noticed it 2 months ago. Since then done 4 motorway trips with long periods sitting on drive unused in between.

Mark