Fuel filter and lift pump.

mackruss · **Posted:** Sat Sep 06, 2008 4:34 am

Okay now that i've just moved myself out of my comfort zone with the EGR and FCV mod, i feel i'm ready to tackle the fuel filter
replacement with the CAT 3 and install a lift pump, i need to check on what model lift pumps are available here in SA.

Firstly with regards to the filter, will it throw a CEL without the water sensor connected as my research has revealed that the CAT will not have the water sensor connected.

Secondly, the lift pump, some members have modified the pump in the tank and others have fitted an in line pump as close to the tank as possible and some pictures i saw on the forum
showed a pump installed in the engine bay close to the filter head although this appeared to be a trial unit. Is this fuel pump not just for the serious off roaders when their vehicle is subjected to varying degrees of inclination or is it advisable for performance and economy as well?

Thirdly, i primed my filter for the first time after doing the EGR and gave it about 6 pumps and the pressure was fine however this was without bleeding through the valve. Question is do i have to bleed if i prime the filter?

Advice required with these mods guys.

Mack.

ATXKJ · **Posted:** Sat Sep 06, 2008 8:01 am

From the factory the 2.8 fuel system is a vacuum system pulling from the engine to the tank.

The main failure in the fuel system is the plastic puc at the bottom of the fuel head -it has the fuel heater & temp sensor plugs in it - the plastic fails over time and starts leaking air. Any of the lift pumps in-tank or in-line overcome this by lightly pressurizing the system. (So this is not an 'off-road mod' - it is - 'I want to drive without fuel problems mod')

The in-tank is easy (Cummings pump + 2 wires) and looks factory - although the in-line may be cheaper - and does not appear difficult (some were there as tests to see if the idea worked).

Also there is a concern that the fitting from fuel line to tank is not vacuum tight - the in-tank eliminates the concern.

Do the lift pump before the Cat filter - those folks who were having fuel problems and did the Cat as a fix - had more problems afterwards. if the system is good - the only issue seems to be correctly cleaning the thread sealant so that nothing gets to the injector pump. And I think they left the water sensor connected but hanging in the engine compartment to prevent a CEL.

I haven't done the Cat yet - I still have some warranty left and for dealers it's a flashing yellow sign that something non-stock has been added (especially since our dealers were not properly trained on diesels)

When I changed filters - I bled it though the valve - although I don't know that you have to.

dgeist · **Posted:** Sun Sep 07, 2008 9:50 am

mackruss wrote:

Okay now that i've just moved myself out of my comfort zone with the EGR and FCV mod, i feel i'm ready to tackle the fuel filter
replacement with the CAT 3 and install a lift pump, i need to check on what model lift pumps are available here in SA.

Firstly with regards to the filter, will it throw a CEL without the water sensor connected as my research has revealed that the CAT will not have the water sensor connected.

Secondly, the lift pump, some members have modified the pump in the tank and others have fitted an in line pump as close to the tank as possible and some pictures i saw on the forum
showed a pump installed in the engine bay close to the filter head although this appeared to be a trial unit. Is this fuel pump not just for the serious off roaders when their vehicle is subjected to varying degrees of inclination or is it advisable for performance and economy as well?

Thirdly, i primed my filter for the first time after doing the EGR and gave it about 6 pumps and the pressure was fine however this was without bleeding through the valve. Question is do i have to bleed if i prime the filter?

Mack.

Answers:
- CEL code without WIF sensor: nope no code.
- Fuel pump: overcome natural tendency of the fuel system to develop air bubbles, etc. Not just for off-roaders.
- bleeding: If you only needed 6 pumps, then bleeding is not really necessary, but if more, you probably need to bleed it, or the pumping is really doing anything other than pressurizing the head. If you put a lift pump in, then bleeding is almost never necessary, as the high-pressure pump on the head will auto-bleed (and return the rest to the tank). If you don't put in a pump, a small bleeder valve is nice to have on the head in place of the bleeder bolt. It's actually nice regardless since you can take fuel samples from a little drain tube easily.

Dan

retmil46 · **Posted:** Sun Sep 07, 2008 11:03 am

WIF sensor doesn't throw a CEL, has a separate warning light on the dash for water in fuel - but same answer, you could unplug the harness right now and it wouldn't trigger the warning light. It's an open circuit until water across the probe closes the curcuit - unplugging the harness makes it permanently open circuit.

Number of strokes on the primer pump doesn't tell you squat about how much air is in the filter head. Without a lift pump, I'd still crack the bleeder screw to check. Air is compressible, fuel isn't - more strokes = more air. On mine, when the filter head was truly air free, I couldn't even get 2 strokes on the pump before it was pressurized.

Going with a 2 micron Cat filter, definitely recommend some type of lift pump installed before the filter. 5 micron and finer filters strip out and accumulate entrained air out of diesel fuel under a vacuum - keeping the fuel under even a slight positive pressure keeps the entrained air in solution.

mackruss · **Posted:** Sun Sep 07, 2008 1:40 pm

What kind of pump should i consider pressure wise and has anybodyhad any CP3 problems after having installed the pump?

Is it easier installing an in tank pump or an external one?

ATXKJ · **Posted:** Sun Sep 07, 2008 2:00 pm

easy depends on what you're comfortable with - neither should take more than 3-4 hours

I think gmctd summarized it as less than 10 psi pressure going into the CP3 should be okay - I don't know that anyone's tested that number.

in-tank
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=26385
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?p=318108#318108

a couple of Kennedy lift pump installs
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=23117
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=25299&highlight=lift+pump

http://liberty.eurekaboy.com/kennedy.htm

BlackLib's Facet install
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=24527&highlight=lift+pump

mackruss · **Posted:** Mon Sep 08, 2008 11:43 am

Thanks for all the info on this topic, is it worth the time and cost to install a lift pump if the primary function of the pump
is to prevent air in the system or are there other benefits?

bugnout · **Posted:** Mon Sep 08, 2008 12:13 pm

If your experiencing air in the fuel head on a regular basis, the first thing you should do is inspect the fuel heater connection for any signs of overheating. If you see any discoloration on the connector or if its wet, take it to a dealer and show them the issue. If they don't offer to replace it for free or under warranty, then let them know you are going to file a report with the Transportation Saftey Board (TSB).

Once you have a new filter head, and are still having air in fuel head issues, then a lift pump is in order. The CAT filter mod is a good mod, but you loose the WIF capability. and the stock fuel filter is not so bad that it warrants that much attention.

I did the in tank lift pump and am very happy with the result. took a good 6 hours to do the job.

mackruss · **Posted:** Mon Sep 08, 2008 12:20 pm

Were there improvements in economy and noise levels from the engine plus better throttle response as reported after having
fitted the pump?

bugnout · **Posted:** Mon Sep 08, 2008 12:48 pm

Biggest improvement was quicker starting. Secondary was better throttle and acceleration, no fuel starvation at WOT.

I avoided doing the lift pump and tried all the other mods first, but if I was to do it again, I'd start with the lift pump.

mackruss · **Posted:** Tue Sep 09, 2008 9:40 am

I have a lift pump in my tank that is a standard model Jeep OEM pump but some of the members chose to replace this pump
due to it not working at the desired efficiency which caused in some cases air in the fuel line and starting issues etc.

Am i understanding this correctly........... :roll:

dgeist · **Posted:** Tue Sep 09, 2008 10:20 am

mackruss wrote:

I have a lift pump in my tank that is a standard model Jeep OEM pump but some of the members chose to replace this pump
due to it not working at the desired efficiency which caused in some cases air in the fuel line and starting issues etc.

Am i understanding this correctly........... :roll:

Nope, not at all (and let me qualify this with the fact that I'm assuming the "eastern hemisphere" spec models are the same as the US.) What you have is an in-tank unit that has a fuel level sensor, a small screen filter for large debris, and tubes running to the top for supply and return of fuel. It has no pump at all. The only pump in the system is a built-in suction unit in the high-pressure common-rail injector assembly (on the back side of the engine). What users have replaced the in-tank unit with is a Mopar part that is stock in Dodge RAM diesel pickup trucks. It's the same dimensions (with some small exceptions) as the KJ unit and DOES have a pump in it.

Many have also simply installed an aftermarket pump inline outside the fuel tank, but there's something to be said for not cutting the fuel lines and having it look "stock". Make sense?

Dan

mackruss · **Posted:** Tue Sep 09, 2008 10:31 am

Thanks for clarifying, i understand what you're saying so simply put, it's now a question of going in tank or in line.

Both these options do not require any modifications to the fuel head, i can leave the breather as it is.

dgeist · **Posted:** Tue Sep 09, 2008 10:34 am

mackruss wrote:

Thanks for clarifying, i understand what you're saying so simply put, it's now a question of going in tank or in line.

Both these options do not require any modifications to the fuel head, i can leave the breather as it is.

Correct. The only modification that is required on both pumps is adding a protected "Accessory-on" power lead and a body ground, both of which can be obtained easily from the existing harness under the left rear passenger seat (see the "it's 10 pm, do you know where your..." thread for all the details).

Fuel filter and lift pump.

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