Starting probs - does this makes sense?

[JonWM]

I have made several posts about probs with starting and had loads of good advice and after much observation I think I may have found some vital clues.
I never have starting probs when the fuel tank is full.
I generally have probs after having done a long journey (>50 miles) and let the van cool down
I generally have probs after journeys when fuel tank is below about a quarter full
When I fill up immediately after a long journey there is noticeable vacuum when I undo the filler cap (somebody did ask me this but I had never experienced the sympton until I filled up tonight for the first time straight after a long journey so couldn't say).
It always starts eventually.

So my theory is that on a long journey, thus emptying the tank a bit, or when the tank is not full then a vacuum builds up which, when the engine is cooling down, actually sucks the diesel back into the tank from the pipes to the engine - so when I when I try and start again it needs to pump all that fuel back in again.

To test the theory I will need to go on a long journey and once completed immediately loosen the filler cap, allow engine to cool and try to start again but in the meantime what are your thoughts and how can it be recitified if my theory is correct?

[wonkanoby]

sounds like breathers blocked

you can try blowing it through with an air line

or try a different cap on tank that lets air in

[dave_aber]

For what it's worth, I usually run the tank down to about 1/4 full every time, and generally fill up as and when it gets to about that level which normally means that I fill up whilst on a run - i.e. been driving for a while, pull in, fill up and go.

I usually hear a sharp intake of air when I open the filler cap. However, I've had no starting issues, hot or cold, before, during or after a run.

[rita]

Hi JonWM,

Worth cleaning or replacing your fuel cap.The cap is fitted with valves..

[missfixit70]

Here's the schematic of the fuel tank & breather system - http://www.lushprojects.com/bongopartsm ... mgno=.html - click on the + symbol on the list on the left & it matches the part description with part no on the diagram.

[Doone]

Jon the symptoms you describe are commonly caused by a faulty fuel cap. So it's a logical place to start... Try replacing it, you could always swop one from another Bongo local to you. If it cures the problem, you can then buy a new cap.

[missfixit70]

From compatible parts list

Diesel tank filler cap same as fitted on 323 or 626