**If you have a 2007/2008 JK CRD then you should read this**
There is a known issue with some of the KJ diesels whereby the diesel fuel heater could malfunction and cause a fuel leak, and possibly a fire. It looks like the first couple of years of the JK diesels also suffer the same problem. Post - 2008 use a redesigned part to avoid the problem.
The fuel filter is located behind it's own bashplate on the transmission cross member under the driver's seat, if you notice fuel leaking from that area of the chassis then you need to take action to deal with the problem.
The fuel filter has three electrical connections:-
- On the bottom of the filter cartridge there is a connector for a Water in Fuel sensor
- On the filter head itself there are two connectors - the left hand one is for a fuel temperature sensor, the right hand one is for a fuel heating element.
The fuel heating element should be controlled by an internal thermostat to ensure that it stays at a safe temperature, however it is prone to failure and will get hot enough to melt the plastic filter head (which is even less substantial than the KJ unit), melt the electrical connections and even melt the insulation off the wires leading to the heating element.
Once the heating element has got this hot the filter head will start to leak hot fuel through the electrical connectors, which will then run back along the wires with the melted insulation...directly under the driver's seat...this is bad. My version of the book of bad says that a combination of combustible fuel, air and an ignition source is definitely not something to be sitting on top of.
The bashplate under the filter tends to collect mud and debris, so a fuel leak might not be obvious for some time. It is worth checking this area regularly for fuel leaks.
The fuel heater is only really needed in really cold conditions, so it is worth considering just unplugging it and taping the connector up - the ecu will be quite happy as long as it can see the signal from the fuel temp sensor.
If your filter head does melt then Chrysler will try to charge you $900 for a replacement which costs $120 from the US....or alternatively you can fit replacement units intended for a marine diesel for the same money that will be more reliable/cheaper in the longer term.
