Needing to prime fuel at almost every start

[GBS]

Recently the ute failed to start and after checking a few things, tried priming the fuel. It then started without a problem. Over the next days the problem was getting worse.  It would need to be primed more often, but would start sometimes without needing to be primed.
Replaced the fuel primer bulb, but this has made no difference. Still having the same starting issue. 

[HUME4x4]

Hey mate, this is a super common issue on the D40 YD25 — needing to prime almost every cold start (or after sitting) usually points to air getting into the low-pressure fuel system somewhere.You’ve already replaced the primer bulb, which rules that out, but the usual culprits are:•  Loose/cracked hoses or clamps between tank → filter → primer → high pressure pump•  Poor seal on the fuel filter housing (especially the small inner O-rings — D40 filters are notorious for this)•  Water drain sensor not sealing properly•  Suction Control Valve (SCV) starting to fail (common on these)•  Occasionally a cracked primer housing or return line issuesCheck all the rubber lines and fittings for hairline cracks — they get brittle over time and suck air when the pump tries to pull fuel.I actually just put together a full video covering the most common D40 YD25 fuel/starting issues (including this exact priming problem) with step-by-step checks and fixes. Might save you some time: https://youtu.be/hGsq7hFDSGsLet us know what you find after checking the lines and filter seals — happy to help further!