DSE Starting problems when below 1/2 tank of fuel

[firestarter_phil]

I have got a 1995 DSE with 125k miles, and am experiencing the following problem.

When the fuel tank starts to get below half full on the gauge (approx 280 miles covered) the engine turns over for approx 15 secs before it will start.

For example, If I am driving down the motorway, and pull over to fill up, with the gauge reading 1/3 full, and then fill the vehicle up, it will take 15-20 secs of turning over before it starts. If however I had stopped with the tank at above half full, it would have restarted immediately.

Once the engine has restarted, it runs fine!

Has anyone experienced this kind of thing before?

The only thought I had on this matter was, it's as if the fuel is draining all of the way out of the fuel pump, leaving this unprimed once the fuel gets to a certain level. Is there a non return valve, or a diaphram which could be leaking which would cause this?

I guess it could also be related to the pickup pipe / sender unit but I am unsure of the position of these and whether this would have a greater effect at lower fuel levels.

Thanks for any thoughts on this
F_P

 

[Disco Mike]

I would lean towards a weak pump with a bad back flow valve. Do you have a way of checking the fuel pressure, if so check it at the rail before you start when you are under 1/3 tank and compare that to when it is full.
Mike J.