Fault: Diesel that will not start or stalls at startup (Peugeot 306 1.9L D/TD)

• Do you have a diesel that does not start or that stalls after startup?
• Your car is old enough? By that, I mean that it has more than 10 years.
• This occurs if you have not rode for a few days or after the weekend?
• If you pump a little on the PEAR / manual fuel pump, the motor starts well and hold more?

In this case, you may have an air intake on your circuit for admission prior to the injection pump. The engine is so poorly supplied and after a period of non-use may not start or start then stall. Other causes may cause similar effects, but I'll only detail here a case of air inlets on the fuel filter. However you will find in the 3rd paragraph, a method to find these vents on a good part of the fuel system.

In this article, I will therefore show you the case of two leaks / air inlets on the filter to a Peugeot 306 1.9 L D (1994 model) diesel. However, this problem can occur on many other engines of the same type.

View of the engine

3 points of the engine that will interest us for this problem are as follows and are marked on this picture of the engine.

1. diesel fuel filter
2. the manual fuel pump. It is also called "pear".
3. the injection pump air bleed

3 possible leaks on the diesel fuel filter

The fuel filter is equipped with a sensor of presence of water. This sensor is located in a screw on the back of the filter Cap. The sensor cable is connected to a plug on the CAP and held by a retaining ring metal. The probe in the plug is fastened by a hard silicone. Over the years, this silicone can no longer be attached to the plug and cause a leak.

The fuel filter is mounted on an aluminium body where the coolant pass. This allows to preheat the fuel for better combustion particularly in winter. The junction between the filter and the alu body can also cause air intake with the years due to a mild oxidation of aluminium support. The o-ring located under the filter Bowl may also be damaged.

The fuel filter is equipped with a purge on the front. It will use just after but if you have a leak at this level, in my opinion, you will see it fast.

How to detect a leak / air outlet on the fuel admission

First it is necessary to put the fuel admission circuit under pressure, to do this pump on the pear until full cure. Then listen if there is the slightest noise hissing or bubble that would betray an air outlet. Also check if a leak appears on each element of the supply circuit (hose, gasket, Bowl plastic, pump body, axle accelerator…). PEAR (hand pump) may also be at the origin of the air intake if its membrane is pierced or PEAR is porous. Finally, check the presence and condition of all the double joints in copper on the arrival and return of diesel on the injection pump, if you detect a problem they can be changed without necessarily remove the injection pump.

In regards to this 306, if you have a leak in the presence of water sensor, you will see it ooze out and there will be a trace of diesel on the hose lying just below it. In doubt, once the sensor is removed, tighten it with your fingers. If it leaks, you will see that the edges of the CAP no longer stick to the silicon.

To see a leak between the filter and the body of the cooling circuit, observe the bottom of the filter to find traces of diesel fuel. In doubt, clean the base with a cloth. Then, after a week of road, pass a paper wipes everything on the base of the filter. If it is soaked with diesel fuel, there must be a leak.

If you have one of these 2 air outlet, you must begin by purging the fuel filter. Without it, even the removal of the water sensor will cover your engine with fuel as in the photo below (and again, then the CAP is just loose).

Purge of the diesel fuel filter

To purge the fuel filter, do the following:

• Connect a small pipe or a small hose on the outlet drain located on the front of the diesel fuel filter.
• Drop this tube behind the radiator (side engine) in a container or a tin can. Do not pass above the radiator because it is higher that the purge and therefore it will not flow.
• Unscrew the knob around the release of purge to open it
• When it flows over, remove the filter cover diesel fuel held by 4 small Allen screw. Take an Allen wrench with rounded head because the air intake cover is a little above the diesel filter. Do not remove the filter drain hose.
• Once opened, the filter will still somewhat empty.

When diesel fuel flow stops you can drop the filter.

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