So I left my 300 TDI defender 90 sitting for 3 weeks while out of the country. Previous to that, it always started right up. When I got back it refused to start until I opened the gas cap to see if it was a vapor lock. Then it started just fine. But, the problem came back the next morning, got better when I left work later on. It’s gotten progressively longer. Engine is turning fine, and idles and accelerates fine once on. Maybe a super slight surging occasionally at idle. Don’t see any fuel leaks or smell diesel either.
Suspecting a slight air leak, I replaced the braided spill off lines as well as the fuel filter and it’s still doing it. Any ideas on the next step before I give in and take it to the shop? I’ve got replacement metal bits and banjo bolts for the spill off lines as well, just haven’t done it or replaces the plastic tube yet.

You are on the right track with small air leak. [ it takes very little and you wont see diesel getting out anywhere ] The main fuel lines are rarely the problem unless damaged. Common points are fuel filter, done but check seal again. And the fuel lift pump. Many of us fit a section of clear pipe just before the lift pump to check for air being drawn from tank end when running or bubbles being drawn back along line at stand still.
P.S. We like it here if you go to introduction section and give a little run down about your self and your Landy.

tottot said:

You are on the right track with small air leak. [ it takes very little and you wont see diesel getting out anywhere ] The main fuel lines are rarely the problem unless damaged. Common points are fuel filter, done but check seal again. And the fuel lift pump. Many of us fit a section of clear pipe just before the lift pump to check for air being drawn from tank end when running or bubbles being drawn back along line at stand still.
P.S. We like it here if you go to introduction section and give a little run down about your self and your Landy.

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I’ll give that a go, thanks! And will do, been haunting this site awhile now but finally gave in and signed up.

Has the vent in fuel cap blocked as you said it started first time after opening cap?

Does it start OK when its hot? Maybe all of your glow plugs have packed in. As they are wired in parallel they will still work even with 3 u/s. Maybe your last one has expired or the wiring has been damaged/detached.

The lift pump was to blame for my 200tdi’s slow starting.

As above worth replacing lift pump as they are cheap and dont last forever(but dont buy the cheapest!). Dont worry about glow plugs, they arent needed unless its really cold