Series 3 1974 2.25 Diesel with air problems (SOLVED)

Looking for some advice and experience. After priming the fuel system using the method described in the Land Rover book, the engine starts quickly and runs like a dream. But the next day there is air in the system again, bleeding only the fuel pump is enough to get it running again. I can't find any leaks. What is the best way to solve this problem?

Also, is my assumption correct that if the engine runs good, at that moment there is no air in the system?

If there is the slightest amount of air getting in there it can still run fine, very very small amounts of air won't stop it, but can stop it starting once it builds up. Check thoroughly around the pump body for any bubbling at all, often when the engine is running a tiny air leak will show up if you look closely enough, a vulnerable area would be the main seal on the inj pump body that the stop cable is on, but do thoroughly check the entire fuel system as bleeding the inj pump is the main bleed point anyway. I had this issue, was a nightmare till it finally bubbled up enough to see, then was straight forward fix making a new gasket for that pump body
Hope this helps

Fuel filter is often the source of minor air leaks.

Leak off return pipes also

I had this a while back...one of the little one way valves in the lift pump was part out of its housing...re-fitted and re staked the its little housing.

I fitted see through fuel pipes just in case I ever had air problems. Problem is I have never had any.
Still, if I do I will at least be able to see the bubbles.

Thanks for the tips! I already replaced the fuel filter and its seals so that should be good. Looking for a leak with the engine running is a good idea, why didn't I think of that. If that doesn't show any leaks I will have a look at the check valves in the fuel pump. I am not sure but I think that the fuel slowly sinks when it standing still so the fuel pump is definitely a suspect. Wednesday I'm working on the Land Rover again.

As I've just suggested on another thread, worth checking condition of the diaphragm in the lift pump.

Have you checked your fuel feed pipe from tank, sometimes if there is a pinhole it will suck air in

Lift pump was a suspect, so today I renewed the diaphragm and the check valves. Also changed all the copper rings in the system. Had it running for 30 minutes without a problem, no visible leaks just like before. Tomorrow I will know if the work from today solved the problem. Fingers crossed.

Yes! This morning it started, so problem solved. Thanks for the tips everyone.

Nice to know its sorted.