Vario 814D fuel draining back

[East Texas Red]

Hi all, I have a worsening fuel delivery problem when starting (OM904L engine). It seemingly began when I was parked on any sort of incline, altho that could be a red herring. The fuel gauge would suddenly show reserve even if there was fuel in the tank and it would take probably 10 to 20 seconds cranking before it would start. CityWest Commercials told me the fuel was draining back, that it could be an extremely small air leak in the low pressure feed which could be very hard to find and that I could try installing a non-return valve to narrow down the section where air was getting in. I put a small rubber bulb-type manual pump in the feed line (the pump has a non-return valve in it), and I noticed that when I operate the pump I can hear air bubbling up inside the tank presumably from the return line which comes from between the fuel pre-filter and the fuel filter. The manual pump and NRV are definitely the right way round. It still takes a while to crank AND today when it finally started there was a violent vibration before the engine settled down to normal idle. I still have the problem that the fuel gauge will randomly drop to reserve before gradully creeping back up (although otherwise, once started, it runs beautifully).

I'm anxious that this could cause knock-on damage, not least because of the wear on the starter motor. I suspect the problem is in the return line or in the feed/return/sender unit inside the tank. Anyone able to offer any insights? Can anyone advise how to isolate air leaks in the fuel system? Am I correct in thinking this has to be in the low-pressure side?

Thanks for reading and any thoughts on this would be greatly appreciated.

 

[Dovey]

Hi i have the same problem ,did you find what caused it .
thanks jeff

 

[jaanus]

Hello, i have sameproblem- i changed new fuelpump, all fuel filters,fuelfilter cups, o rings. nothing helped. have you guys found out what was problem?

 

[bladecrazy]

guys, is there any 1 way valves along the fuel system , could one not be fitted inline? to keep pressure.

 

[jaanus]

Hello. i add 1 way valves in both fuel line. Didnt worked, same problem. no visible leaks.

 

[sean.ie]

Hi, I had this issue with a Vauxhall Vivaro, I changed the fuel line including the hand primer from the fuel filter to the tank. It fixed the problem. Good luck and I hope you can find a solution