huge delays in feed update (2-10 hours or even more)

[Холидей Пираты]

I have a huge problem: the updates of my feed happen not as the posts go out, but with a huge delays (2-10 hours or even more). My feed is http://feeds.feedburner.com/piratesru/

Same happens with the e-mail list - when the daily e-mails go out, some last posts actually don't get there. Obvsiouly, they are not in the feed, so they don't make it to an e-mail.

This problem persists for several months and I have got a lot of complaints from subscrubers - as we are posting hot travel deals that can be valid for very short period of time, so they want an update instantly!

Neither ping nor recync doesn't help.

P.S. Just in case - I don't use WP Cache or Super Cache plug-ins.

[Maks Verver]

It looks like your source feed redirects to your FeedBurner feed, even when it's being fetched with FeedBurner's User-Agent string. If FeedBurner can't fetch the content of your feed, it won't be able to update it.

What's curious is that if you are able to update the feed sometimes, then that means this doesn't always happen. Are you sure there is no caching going on anywhere else, maybe in front of the webserver that serves the redirect?