Diesel start issue

[Whittall7]

Hi all, new member with a problem which I'm hoping for some help with. 

I have mk2 1.8 tdci which last week wouldn't start. Had the issue in the past with the diesel filter. So I put a new one in, bled the system got her running again. Now every so often she won't start again until I bleed the system again. She'll then run again for a few starts but after a day or so nothing again. I have no error codes only get a engine malfunction when she won't start. When she's running no issues what so ever. 

Im stumped anyone have an idea what the issue maybe?

thanks in advance 

[Tdci-Peter]

On 18/10/2016 at 2:21 PM, Whittall7 said:

Now every so often she won't start again until I bleed the system again. She'll then run again for a few starts but after a day or so nothing again. I have no error codes only get a engine malfunction when she won't start

Hi,

First a couple of questions:

How are you bleeding the fuel system? The LP side of this system runs under suction, there is no tank pump (unless you have a very unusual exception). It is the LP side that needs all the air removing. The HP side of the pump is self priming once fuel gets to the pump. But the pump will not suck air. It is not advised to loosen any of the 1500Bar High Pressure connections, if they leak, there is no alternative to replacement.

How are you reading the codes? A generic OBD2 scanner will read most engine codes, but a Ford specific system like Forscan (from £15 if you have a windows laptop) is needed for a deeper diagnosis. If the light coming on is the engine systems light, (cog with ! in it), then it is more likely to be a non-OBD2 code.

It sounds like air is leaking into the fuel system. The fuel filter gasket is a prime suspect, but cracked or damaged hoses, or bad hose connections are possible.

The safest and best way to prime the fuel system is with a priming bulb inserted before the fuel filter. Then there is little or no chance of getting dirt into the line leading to the expensive & sensitive pump & injectors. A problem here is that when the bulb is removed, air enters the line. I have fitted a non-return valve into the feed line to the filter. This would also reduce the amount of air entering the system while the engine is stopped.

I bought the 8mm version of this: http://www.ebay.co.uk/itm/291512397207

It is also possible to suck air out of the upper vent in the filter, but as this vent leaks when unscrewed, it needs a fair amount of suction to beat the rate at which air leaks in!

Why these cars did not have a priming pump as standard, I do not know!

Peter.