SAFETY WARNING: unplug your fuel heater element

retmil46 · **Posted:** Sat Dec 08, 2007 5:32 pm

Guess I've got belt, suspenders, and a hernia truss to boot! :lol:

Kennedy lift pump, replaced the stock filter head with a Stanadyne, have a Cat 2 micron downstream of the Stanadyne, plus a fuel pressure gauge to tell me when they're getting clogged.

gmctd · **Posted:** Sat Dec 08, 2007 6:14 pm

Could be, threeweight, but that presents another problem: 2micron filtration is fine in a pressurized system, but detrimental in a draw system - pre-filtration should not be less than 10micron, and most fuel-system engineers recommend 20micron, where system design specifies pre-filtration in the draw circuit.

Which is the second problem area with the Bosch CP3, and solved by the Dodge boys - the internal lift pump is powerful, serving both 20"vacuum lift and 180psi (in the Dodge\DMax) head service, but the chute between the medium-pressure lift pump and the high pressure injection pump is, of necessity, internal - and nigh on impossible to filter, where Bosch recommends 3microns as suitable for the CP3 CRD system, to protect the injectors.

Whaddaya do? Can't put a 3-2 micron filter on the lift side, or Diesel fuel aerates as lift vacuum increases, due in part to the fuel manager posted at hi-point lookout, and the pump can cavitate, causing erratic pressurization.

Don't even begin to think them Dodge boys are enny smarter that the Jeep guys, tho - they may have added a lift pump to solve the filtration dilemma, but they placed the vane-type lift pump up on the fuel manager housing, way higher than the fuel tank.

A sliding-vane type pump is not spec'ed for draw service, unless it is system-primed - 'nuther words, the vanes must be submerged in fuel in order to pump the fuel - it is not inherently self-priming - and initially pumping dry damages the vanes and cylinder surfaces - Carter tole them guys that, which they promptly ignored, also.
So, what happens when ya hi-mount a not-self-priming lift pump on the hi-mounted fuel manager? (snicker) Ya get to replace the lift pump several times a year, not to mention the VP44 injection pump, which craters non-recoverably with no pressurized fuel on the inlet = new injection pump almost every time the lift pump fails.

Then, they proceeded to do the same misteak with the '03-'04 CP3 CRD system: Carter lift pump on the side of the fuel manager, way above fuel level - result? - lift pump failure = engine stops - doesn't hurt the CP3, but the draw-spec'ed CP3 cannot draw thru the damaged lift pump, and particularly not when the owner has installed banks of 2micron filters in the pressurized line - which ain't no longer pressurized after the lift pump fails, right?

In ought five, the Dodge boys at long last attempted to recover by engineering-in the in-tank module you've so recently seen here - lovely piece, what? - soon as it appeared to be a workable solution, they offered a factory upgrade kit, replete with lift pump-equipped fuel module, replacement wiring harness, and instructions, retro to include the '98-'02 24v VP44 trucks as well as the Carter-equipped '03-'04 CP3 versions.

So, long story short (as usual, right?), what's good fer them is as good fer us - and, if ya want increased filtration, don't stick it in the draw circuit - pressurize the system for best reliable results

That's my story, and I'm stickin' to it.........................

valkraider · **Posted:** Sat Dec 08, 2007 7:10 pm

Mine is very slightly scorched. NHTSA Complaint filed....

ATXKJ · **Posted:** Sat Dec 08, 2007 8:49 pm

My argument on the problem is that it's not the design - it is the manufacture. Specifically of the plastic heater puc.

Just based on the posts on the forum.

1)There are people who do not have problems - and they continue to not have problems.
1.A)Some of those without problems have installed 2 micron CAT filters - without adding problems (a couple of folks have messed this up too - so not as conclusive).

2)There are folks who have problems - and they can't get them fixed, ongoing - constant problems.
2.A)Some of those who had problems have solved them by changing to the Racor - no lift pump - no other changes.
2.B)those who were having problems and installed the CAT filters - seemed to make things worse.

In all of the cases - the filter head stayed in the same place.
The leaks always seem to be coming from the heater plug.
It takes a much large hole for diesel to leak out than it does for air to leak into a vacuum system. So air would be pulling in for a long time before an external leak is noticed.

The symptoms are consistent with manufacturing problems in the plastic puc - molding problem with the plastic flowing around the heater plug, resulting in air leaks at the heater plug.
i.e. if you've got a good one - it doesn't seem to go bad, but if you have a bad one you can't fix it until you change the head (or overpower the vacuum with a lift pump).
That said - I don't think the good ones will stay good over time - how long I don't know - I'm guessing 10 years is the design life, plastic and heat are bad combinations.

My plan is the in tank lift pump, a Racor head and a cooler on the return line.

gmctd · **Posted:** Sat Dec 08, 2007 9:51 pm

I'd have to agree with that - the Dodge heater is inside the aluminum fuel manager housing, so prolly fares better, for many reasons.

Personally, that Jeep manager-thingy is just not aesthetically pleasing to my senses - the Fleetguard is so much more........utilitarian, Jeep\like - knowwhuttimean?

It serves to accentuate that little Desel engine, prospectively adjacent to it.

Bob V · **Posted:** Sun Dec 09, 2007 11:40 am

IMHO the fact that the with the key on and the engine not running there would be no fuel flowing through the filter, and since the fuel temp sender is down stream from the heater it would not know how hot the fuel is getting at the heater. This causes the heater to stay on too long and melt the housing. I had no problems till the key was turned on with the engine off, the next day, melted housing and leaking fuel, and, air in the line. The housing was replaced about 6 months ago and no problems since.

gmctd · **Posted:** Sun Dec 09, 2007 1:16 pm

The fuel heater is it's own temperature sensor, totally separate from the Inlet Fuel Temp sensor, over in the other leg of the puck - that one is strictly for the ECM - the heater is made of temperature-variable stripping, sorta like in your toaster - when fuel is cold the strip gets hot - as fuel warms up, the strip makes less heat, up to ~85deg, when it will not heat at all

Even with key ON, engine not running, the heater cannot damage itself if submerged in fuel, as the mass density of the fuel conducts the heat away from the heater - it is when it is submerged in air that the problems start, and with the fuel manager being higher than the engine, there's gonna be air in the top of the assembly, right where the 'puck' is situated.

I've not had any hands-on with the Jeep version, but the Dodge 'puck' is designed such that inlet fuel flows into and around the channel inside the module, with windows in the inside diameter wall to allow the heated fuel to exit into the filter chamber - all fuel must pass thru the heater.

Goglio704 · **Posted:** Sun Dec 09, 2007 1:18 pm

The heater is self regulating. As its temperature rises, its resistance increases and the current drops. It is powered whenever the key is on, and that is a bad idea. A relay should have been included so the computer could shut this thing down if the key is on and the engine is off. As a matter of fact, the fuel pump logic would be nearly perfect. :idea:

The temperature probe in the head does not control the heater at all. The temp probe is an input to the computer. It is used to control fueling and the amount of return to the tank.

Oh, looks like gmctd beat me to it on this post.

gmctd · **Posted:** Sun Dec 09, 2007 1:56 pm

Great minds think alike, eh..................

ATXKJ · **Posted:** Sun Dec 09, 2007 6:57 pm

gmctd

so when are you going to figure out how to install the Fleetguard?

gmctd · **Posted:** Sun Dec 09, 2007 7:11 pm

I know how - just haven't found one, yet

- the correct version is the '03^ CRD model, with the vertical mounting flange - the engines don't crater, and the junk yard dogs won't strip a late model running motor

ATXKJ · **Posted:** Sun Dec 09, 2007 7:22 pm

any ideas on what the Dodge part number would be?
(the online searches like the filter - but not the entire module)

gmctd · **Posted:** Sun Dec 09, 2007 7:44 pm

Don't know it - was just gonna hit the boneyards and carry my captive around for conversation starter - or, waltz them out to the truck for show'n'tell, if I have installed it, therein.

onthehunt · **Posted:** Sun Dec 09, 2007 8:33 pm

Tell me again how the fuel heater overheats with fuel constantly running through it?

gmctd · **Posted:** Sun Dec 09, 2007 8:50 pm

Cain't tell ya that.............'cause it ain't gonna happen - at least, not in the Dodge fuel manager - they may have similar failures, but in the ~3yrs I've been member of several Dodge forums, I have not seen any reported incident of such - unlike here, as you well know, eh?

"Even with key ON, engine not running, the heater cannot damage itself if submerged in fuel, as the mass density of the fuel conducts the heat away from the heater - it is when it is submerged in air that the problems start, and with the fuel manager being higher than the engine, there's gonna be air in the top of the assembly, right where the 'puck' is situated. "

Edit in: unless the fuel manager is pressurized, as in the Dodge system

Could be I just overlooked any reported incident(s) over there whilst searching for sumpin else - or while being my usual affable, helpful (know-it-all) self?

Naaaaahhhhhhh! It ain't gonna fail.........

onthehunt · **Posted:** Sun Dec 09, 2007 9:31 pm

Fuel is pulled from the tank and enters the heater and filter in that order. How does the heater overheat?

gmctd · **Posted:** Sun Dec 09, 2007 10:02 pm

The heater must be immersed - submerged - in fuel to function - if fuel is just trickling thru it, as would be with an air pocket, some area would be cooled by the trickling fuel, some would not

Two ways to look at it - you're either using the element to warm the fuel, or using the fuel to cool the element - either way: little fuel = little function, no fuel = no function.

Experiment, Science 101 - take your submersible cup-heater coil, fill the cup half full (or half empty, if you're still in grad school), plug in the heater, see what transpires - also takin' a mo' to note the specific warning taped on the power cord of that convenient device: heater must be fully submerged to prevent damage - do not leave unattended.

I see where you're coming from, no sweat - to me, that darkened, burned thermoplastic connector is mostly explainable by that Science 101 experiment - rest of the explanation to be considered is simple product defect.

Pressurize the fuel manager, and the defect will evidence itself much earlier on, way B4 the plastic begins to char, as the damaged seal will begin to leak pressurized fuel.

An air leak can exist in a vacuum-type system for years with nary a trace of wet - try that in a pressurized system - as demonstrated by retmil46's(?) failure in that intersection, with the prime pump.

Post your thoughts, dude - that's what forums are all about.

Come, let us reason together....................

onthehunt · **Posted:** Sun Dec 09, 2007 11:35 pm

I think it is impossible for the fuel heater to overheat from the lack of fuel to cool it. Fuel doesn't trickle through it and if it had an air leak that bad the engine wouldn't run. Faulty parts is believable. Seals leaking are caused by inferior o-ring composition and people pumping the crap out of the primer pump. Same goes for the heater elec connection. Pump a known good filter head enough and you will cause it to leak. Air leaks can exist in a vacuum system but they would have to be minute or you will have symptoms.

gmctd · **Posted:** Mon Dec 10, 2007 1:16 am

Good input - first, I must admit that I have had no in-depth hands-on with the Jeep heater, only closely scrutinizing ours in-situ - it appears pristine, as new, but I did immediately pull the electrical connector upon reading this thread, to give me some time, for, as the friendly gynecologist sez: 'this bears looking into'.

I have had hands-on with the Cummns\Fleetguard manager, and fuel will only trickle into it if the lift pump dies and the CP3 is in vacuum-draw mode - the fuel manager is highest point in the Dodge system, as well

First thing to consider is start-up -

Jeep - key On, Wait-to-start, the fuel heater is instantly on at up to full current, depending on local ambience - there is little fuel in the heater due to it being the high-point in a vacuum draw-type system, empirically proven to harbor air pockets - there is no fuel flow into the heater, as the system lift pump is on the back of the CP3 injection pump, which is not pumping because owner\driver is in WTS mode, eagerly anticipating, but not executing - heater is heating, fuel is not even trickling, puck begins frying - driver hits START

Dodge - key On, Wait-to-start, fuel heater is instantly on at up to full current - aux lift pump is instantly on at full output, instantly pressurizing the fuel manager head, priming it if necessary - fuel heater is fully immersed in fuel at system pressure - driver hits START

Now, consider RUN -

Jeep engine starts soon after driver goes into crank mode - engine is idling with minimal fuel trickle....oops..fuel flow -- if heater was exposed, the idling vacuum-stimulated trickle is not gonna submerge it - fuel heater is steadily heating - driver eases off the line and moves up to speed - any air pockets in the fuel manager will remain, as fuel level is unchanging as, with no restriction in fuel tank, system vacuum does not equalize across filter - manager is at highest point in system
This is similar to the engine coolant system, where, after flushing and refilling, the system must be opened and air bled and system topped-off several times to eliminate residual air pockets - while it is a closed system, it is a dynamic system, where pressure at the pump inlet is lower than at the pump outlet.
While CP3 develops lower pressure at its inlet than atmospheric pressure on the fuel in the tank, the restriction is the filter in the fuel manager.

Dodge engine starts, fuel flow is at a trickle, but it's a pressurized trickle - any air pockets have been fuel-pump compressed by the incompressible liquid - fuel heater is fully immersed in fuel - no problem exists as pressurized trickle-flowing fuel is continually exposed to therms in the heater gallery

So - how does that sound to you - have I missed anything - overlooked anything - forgotten to factor in some critical system operational concept? Or, is it totally off the wall?

onthehunt · **Posted:** Mon Dec 10, 2007 1:28 am

Sounds plausible. Anything is possible as I can't prove it either way.

SAFETY WARNING: unplug your fuel heater element

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