Help needed by mechanics?

[Gazbo]

Hello fellow mechanics/self fixers.
I am working on a merc vito at the mo and i know some folk on here are clued up on all vehicles. This prob is a head scratcher.
It truns over but wont fire, its as if it has to bleed itself everytime you start it, even after standing for just a minute or so. I have changed heater plugs as a couple were slowing up. I have changed the fuel regulator o-rings and cleared the engine codes. It was ok for a week, though it still took a few winds before firing. You can see the fuel in the line draining back to the tank? Any thoughts?

Cheers Gazbo

[lord lucan]

Hello fellow mechanics/self fixers.
I am working on a merc vito at the mo and i know some folk on here are clued up on all vehicles. This prob is a head scratcher.
It truns over but wont fire, its as if it has to bleed itself everytime you start it, even after standing for just a minute or so. I have changed heater plugs as a couple were slowing up. I have changed the fuel regulator o-rings and cleared the engine codes. It was ok for a week, though it still took a few winds before firing. You can see the fuel in the line draining back to the tank? Any thoughts?

Cheers Gazbo

try it with the fuel cap of tank could be vacuum in there. make sure the leak of pipes are not drawing in air over night

[jaky cakes]

I had a similar problem with the wifes VW caddy van. I had every part of fuel system apart and found nothing. eventually swallowed my pride and towed it to the dealer. they found nothing. the van was there for two weeks - before the workshop foreman decided to swap the ignition barrel key chip reader coil and hey presto!!!.
try cleaning the ignition key with the wife's toothbrush to remove any small deposits of grime. if that don't work, then try to see if immobilizer is cutting in and stopping fuel pump when turning over.
you could also try to remove the stop valve from the pump or short it open with a 12v supply from battery to see if it is the immobilizer.
also remember reading somewhere that some diesels have a smaller priming fuel pump in/next to tank - if so - can you hear it whirring when ignition is on?
BTW key chip reader coil was only £30 fitted - so not a expensive job.
hope this helps!!

[M35A2]

If the fuel is draining back into the tank then it very much sounds like you are getting air into the system.

I had a Peugeot 106 diesel that you could see air bubbles in the clear fuel line being drawn into the IP. I traced the problem back to where the fuel line went past the passenger seat. When they fitted the seat it nipped the fuel line causing a very small hole. It was sucking air into the system from this.

Check the fuel lines all the way back to the tank, check the fuel filters (including the small inline ones that can be found on top of the tank) check all joins.