There is nothing wrong with or defective about the fuel heater - the problem is Jeep's mounting of the fuel manager, borne of necessity and convenience: limited real estate - that, and conformal compliance with Bosch specs: CP3 is designed for draw-type service and does not require aux external lift pump.
This resulted in the failure - the fuel manager is way higher than the level of the fuel tank, higher, even, than the CP3 injection pump - air, being less dense than fuel, is gonna seek the highest point in the system - all system air is gonna accumulate in the top of the fuel manager, which eventually exposes the heater element - designed to heat fuel, which is denser than air, it's just natcherly gonna fail in air - that is a given.
Dodge uses same configuration, where the fuel manager is way higher than the tank, but they stubbornly ignored Bosch rec's, installing a pre-manager lift pump to ensure adequate fuel level in the head - guess what? - they don't have fuel heater failures over there - and, it's also an epoxied ring at the top of the fuel manager.
Mosta you guys are prolly too young to remember, but, once upon a time, all automotive fuel systems were draw-type, where the mechanical fuel pump was attached to the engine block, actuated by a lobe on the camshaft, with no pre-filtration.
'Course, they all used a diaphragm-type pump, most excellently suited to draw-type service - some higher output engines even used stacked dual-diaphragm pumps - the comparatively huge volume-displacement of the diaphragm could pull a lotta vacuum on even the most recalcitrant of intank fuel pickups, right at 30"HG - fuel was not, indeed, lazy in assembling at the pump entrance back then, long ago and far away.
So - the resolution for the solution is an aux lift pump, or lower the fuel manager such that it is not the high point in the system - below tank fuel level would be most suitable for fuel heater longevity, as well as proper operation of the draw-from-tank configuration.
But, don't even blame that heater for the inadequacies of the system, eh?
Uffe - the later Bosch CP3 systems control fuel tank temperature by juggling the return fuel volume - it is controlled by a Fuel Temperature sensor probe in the fuel manager head - your early system, maybe even all the Euro systems, may not have that function - our system will give an official DTC if the sensor is bad or disconnected\missing
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