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EFI Fuel Filter Upgrade And Other Fixes


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Tired of the hassle dealing with changing out your YJ style frame mounted fuel filter?  Me too.  Messy and time consuming.   Thanks to guidance and suggestions from Moses, this is the new plan:

 

In tank pump exits with 5/16" efi rated hose to a 6 or 8 AN filling into a spin-on fuel filter installed in same location as the old YJ filter.  From there another 6 or 8 AN fitting and tie into the metal fuel line that heads forward to engine.  Removal and filter replacement will be a simple affair.  Ordered the RM350.

 

http://www.fstperformance.com/

 

In the spirit of redundancy will also install the MOPAR in line 12 volt fuel pump and mount along upper cross member in front of tank.  This will be fed from the other tank pick up to a AN fitted pre-filter, then pump and another lead from pump to the new spin on filter, but blanked off.  Should the need ever arise to switch pumps, simply unscrew the in tank pump supply line and attach the supply line from aux pump.  The unused end will be properly capped off from debris in either case.  Then unplug in tank pump from power harness and plug in the aux pump, prime and off we go. 

 

While on this project will also add an auto meter dash mounted electronic fuel pressure gauge that will get its signal from the fuel rail schrader valve port.

 

when we go for a long trip and perhaps also tow the pack mule trailer, the rear of jeep tends to sag leading to a nose-high attitude.  Not very safe road manners, even with sway bar attached and the departure angle is compromised.  Will install a set of gabriel hi jacker air shocks to level the rear end and, as necessary, adjust departure angle on trail obstacles and mitigate smashing the new gas tank! These shocks are 22" extended and 14" collapsed.   This will not affect the existing rancho 9000s.  In cab will  have a dual paddle controller to handle air management duties.  like this

http://www.ebay.com/itm/320511185841

 

Once the parts are here, along with new aero tank, etc etc will photo-document the progress of these important and helpful upgrades and post here.

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This all sounds good, Mark...I'm assuming you've been running 5/16" to this point, not 3/8"? Also, for clarification, when you hook up the auxiliary pump and have it set to run as a backup, you mention an extra pickup in the tank. That second pickup drops to near the floor of the tank and is also protected by a sock filter, right?

So, the only distinction when you switch over is that the external Mopar EFI conversion kit pump is pulling from outside the tank—like with the EFI conversion kit method. With the switchover, you're still using the PCM signal to activate the external fuel pump, right?

I'm very impressed that you're taking the fuel system to this level, as fuel supply is critical on an off-pavement, destination 4x4. Your photos will be helpful and valued when you get to that stage!

Moses

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its 5/16" efi rated line from top of internal pump assembly  to the YJ filter.  CRO33000076   exiting the filter is 3/8" going fwd.  why the jeep engineers made the inlet different from the outlet is unknown.  Perhaps to stupid proof installation so the tech does not install filter backwards?  

 

the pick up for the mopar efi conversion exits top of tank on driver side and the 'straw' goes to the floor of tank but there is no servicable internal fiter, thus the need for an external  pre  pump filter just like the kit directs.

 

so:

 

in tank pump with screen/sock to new spin on filter.

 

or

  tank to pre filter to aux pump to new spin on filter. 

 

searching for an acceptable pre filter that also uses AN fittings.  need data on micron rating and volume, but its on the suction side and not under EFI pressures.

 

as for power, yes whatever was designed in the mopar efi kit is how the pump is powered.  I have weather pack plugs.  unplug one, hook up the other and go. (that's the plan, anyway!)

 

i have suffered thru several years of fuel delivery issues, from one problem to another and its always on my mind driving along it can die at any moment.  This time i'm throwing some $ at it to make it easier to service, etc 

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This sounds really slick.  For reference, the RPM 350 rates 300 GPH flow at a 4-micron filtration level.  This is great for fine filtration plus adequate fuel flow.  Again, Mark's injectors require 24 lb/hr X 6 cylinders = 144 lb/hr.  Gasoline weights approximately 6.2 lb. per U.S. gallon, so flow demand for the stroker six at maximum injector flow (something like wide open throttle under severe load and then some!) would be 23.22 gallons per hour.   

 

That said, this filtration should handle a dozen 4.6L stroker sixes with these 302 Ford V-8 injectors!  And with 4-micron filtering...This is really tight filtration, designed for high performance and racing fuel supply systems: The RPM 350 is rated 260 PSI maximum pressure!!!

 

Did FST indicate filter lifespan with typical pump gas and a clean, capped system?  How do you know when to change a filter—pressure drop?  Is there a bypass function in the event of clogging or is this 100% flow through the filter at all times?  I would think 100% flow through the filter, as you don’t want injectors exposed to unfiltered fuel at any time.  Am I right?

 

There should be plenty of filter media (surface area) in these filter canisters for reasonable filter life.  OEM filters, from everything we’ve researched, must be 10 micron at best.  FST's RPM 350 is much finer yet flows plenty of fuel!  If you keep your tank clean and capped (it’s sealed, too), the filters should last.

 

The mounting bracket and ports provided are for racing applications.  FST is known in off-road racing circles and the high performance/racing industry.

 

For the pre-filter, I would go back to the CARQUEST filter catalog and check out the threaded filters for the G.M. TBI applications.  As you share, the pick-up side of the system does not require high pressure rating, and the G.M. common TBI systems operate at 9-14 PSI regulated pressure.  These filters have threads (common fuel pipe type) at each end of the filter, and even if you need adapter fittings, you would still have quick removal/replacement capability.  This filter should have more than enough flow, target a 350 or 454 V-8 engine application.

 

The takeaway for all of us is that you should keep the fuel system as clean as possible at all times.  Capped systems with EVAP should have all of the EVAP hoses and the canister in top condition.  Keep dirt, trail dust and Nevada alkali powder out of that pristine new Aero tank, Mark...

 

Buy yourself a set of quality flare nut wrenches, maybe two of each for the common sizes.  I recommend carrying a small plumber's chain wrench, too!  I've had a small Wheeler Manufacturing chain wrench, gifted to me in 1970 by a plumbing supply sales rep when I worked as a light- and medium-duty truck fleet mechanic. 

 

This tool has performed wonders for forty years, on everything from vintage British motorcycle chrome fork head plugs (high torque, hex headed and irreplaceable!) and stuck spin-on oil filters with collapsed canisters, to frozen brake tubing flare nuts!  Here's a link to photos of the tool and my flare nut wrenches at the "The Right Tools and Equipment" forums:

 

http://www.4wdmechanix.com/forums/index.php/topic/81-chain-wrenches-and-flare-nut-wrenches-for-tubing-nuts/

 

There is also this Vise Grips model: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=Vise+Grips+chain+wrench.  In a pinch, if the chain links are short enough, you can grip a softening flare nut.  A chain wrench can even grip near the base of a collapsed oil or fuel filter! 

 

My small Wheeler chain wrench will grip a rusted brake flare nut securely, and that's small.  The same tool will also grip a collapsed oil filter canister near its base.  The Vise Grips tool will only drop to 5/8" diameter, too big for most brake—or even fuel—tube fittings.

 

Moses

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When I asked Mark the questions in the last reply, he went directly to FST and got these answers:

"We are currently on five "Best in the Desert" vehicles (trucks & buggies) for that very reason, here are a couple of quotes:

• Kent Kroeker, owner/President of KORE Off-Road & winner of the Baja 1000: "We've tried every high-performance fuel filtration system on the market and all have fallen short of our expectations. The only system that works in all conditions is the FST - for three simple reasons: flow, surface area, and efficiency. That's why we trust FST when we subject a $100,000 V-10 Viper motor to the rigors of the Baja 1000. FST is no-compromise performance. Period."


• Gary Mills, Owner of Mills Motorsports; 2nd in class / Baja 500 this year: "FST filters provided us clean fuel for 500 of the hardest miles on planet earth."

Both of the above "were" having trouble with clogged fuel injectors until they switched to FST.

Mark - it strictly depends on the fuel, or contaminates and water in the fuel, I should say. We have some (racers) that change them weekly, others once a year (if they don't get a bad batch of fuel at a track)....some quarterly. We've had people run 6 months, then after changing (the filter), get a bad load of fuel and plug-up in a week.

I like to recommend (if you don't have a fuel pressure gauge) at every oil change, remove the (fuel) filter, drain in a clear jar...if the fuel looks clean, oil the seal and put it back on. Do this until the fuel starts to look ruddy, dirty, then change it. If you run a fuel pressure gauge on the "Out" side of the filter, you will notice a drop in the pressure as it gets dirty.

I trust this helps...Rick"

 

You can see FST Performance products at the website: http://www.fstperformance.com/.

 

post-1-0-15538700-1371596658_thumb.jpg

FST RPM 350 Filter and mounting stand...Photo courtesy of FST.

Rick should know, and I agree completely...I had shared with Mark that pressure drop at his gauge would be a signal for a clogging filter, since Mark plans to mount the pressure gauge sender at the fuel rail—post pump and FST filter.  Good to get Rick's additional impressions. 

 

As a footnote, I worked with BMW (cars) at the dealership level in the early ‘80s.  The OEM paper fuel filters would plug with one water-contaminated fuel fill, and the cars would come into the service department by tow truck! 

 

I know very few who can afford a tow from the Rubicon Trail or Fordyce...and it's very dispiriting to turn a "fun vacation" into a trailside fix that goes on for days.  Being "the broken 4x4 story" won't elevate your stature among fellow four-wheelers, either!

Paper matrix fuel filters are designed to swell and stop fuel flow to prevent damage to sensitive components in the FI system.  On BMW/Bosch systems, the weak link of that era was the expensive fuel distributor, which had zero tolerance for water exposure.  The fuel filter was an inexpensive service replacement item.

 

Pleased that we made the FST connection.  This is a high grade filtration solution for any off-road vehicle subjected to extreme driving, dust and remote driving conditions.  Mark has been helpful in illuminating his CJ8's fuel supply system needs, discoveries over many years of hardcore four-wheeling...Glad we opened this subject, the end result will be more reliable, safer four-wheeling for those who head out for primitive destinations!

 

Moses

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Follow up Q:  in aviation, fuel and oil filters are cut open for examination.  Requires a special can-opener tool.  Do you have a simple suggestion to carefully open either  without contaminating the sample?  I tried once with a band saw and just made a mess.  might be interesting to see what's being captured in a closed-cell filter.  

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Ironically, in searching for a Wheeler Manufacturing small chain wrench (none available today like my 'sixties version), I recalled a tool that might be useful: the exhaust tubing cutting tool used at muffler shops. 

 

I have an inexpensive exhaust tubing chain cutter from Harbor Freight that is not in its inventory any longer...It has a longer chain, which many do not have, you can actually wrap it around a filter canister—most chain cutters are designed for only 3" to 3-1/2" diameter maximum.

 

The chain has cutting wheels at the links...It works, although the sharpness of cutting wheels is marginal, a metallurgical issue.  There may be a better quality tool available in this design.  It's considered a muffler shop tool.  A tool like this should cut through a filter canister without trouble, leaving minimal debris, kind of like an electric can opener cut.

 

Here's another tool from Harbor Freight that, unfortunately, will only open to 3-1/2" diameter.  (Lisle makes a similar tool.)  Maybe you could modify it, possibly worth a try if the cutting wheels are decent.  In principle, this could do the job you want for minimal cost:

 

http://www.harborfreight.com/exhaust-pipe-cut-off-tool-69327.html

 

If you want to step up to aircraft filter tools, they can be bought without spending a lot.  Here are two examples that are actually affordable if you take filter inspection seriously and plan to use the tool regularly:

 

http://www.skygeek.com/airwolf-afc-370-rotax-oil-filter-cutter.html?utm_source=googlebase&utm_medium=shoppingengine&utm_content=airwolf-afc-370-rotax-oil-filter-cutter&utm_campaign=froogle&gclid=COyG3aGZ77cCFQXZQgodOxsA8Q [This is for Rotax filters, research their diameter!]

 

http://www.skygeek.com/tempest-aa471-filter-oil-media-cutter.html

 

The Tempest tool at $41.19 plus S&H would be a good investment...Investigate the filter diameters this will work with...

 

Moses

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  • 3 weeks later...

For the standard inline external pump, I am designing the aux pump system and have three of them here.  The old one, a replacement and a 'gotta carry a spare' one.  In the process of converting to -AN 6 in/out hardware, I stumbled upon an interesting discovery.  

 
The out of the box fuel pump uses a screw-on adapter designed to accept 5/16 input line.  Most installers use 3/8 line and just clamp it down.  Problem is the 5/16 brass inlet fitting severely restricts the suction end of the pump.  It's already working hard enough, why choke it?  
 
By adding a 3/8 inlet fitting more fuel will pass and may eliminate starvation issues.  Will get pix up later, but research shows this is true.  We'll see once the system is on line.
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Umm...On the suction side, a larger orifice would lift more fuel, and that could be a liability.  Fuel is mass and volume, and the pump motor would work harder moving the higher volume of fuel, especially as the pump first starts its cycle. 

 

On the push side of the pump, they want the larger hose to prevent any restriction.  Volume gets controlled by the pressure regulator at the EFI rail.  In your two-rail system, the excess goes back to the tank.  If you use a larger pickup hose, there could be more volume going back to the tank.

 

There may be a sound engineering reason for that 5/16" inlet.  Is it impractical or difficult to use a 5/16" pickup hose to the pump and 3/8" to the rail?

 

Moses

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The pick up outlet on tank is 3/8 as are the fittings on the pre filter.  Research shows the screw on fitting for inlet is Ford sourced.  Had to change that to accept the  AN hardware.  Will research further.  Several lengthy discussions on this issue at forums.

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Well, if it simplifies the install and hose matching, there's likely no harm in doing a 3/8" fitting on the pick up side.  If you run 3/8", I do want your feedback on this, including pump heat in service. 

 

One way to take the "mystery" and second guessing out of this issue is to measure amperage draw at the pump while it's operating—using 5/16" versus 3/8" pick up hoses.  This is a more scientific approach and would indicate the load on the pump.  If there's a "restriction", as you suggest, with the use of a 5/16" hose and fitting, that will show up in higher amperage draw.  The measuring device needs to read 1/10ths of an amp or smaller.

 

To be clear, the rating on the pump should be with the furnished or intended fittings installed.  Unless vendors are substituting smaller (5/16" versus 3/8" hose size) fittings—with the pump's flow rating based on the bigger fitting—there's little risk of "starving" the engine for fuel.  If you have suspicions about the pump's intended input/output fuel fitting sizes, research the manufacturer's ratings and the fitting sizes recommended.

 

Volume is an even smaller concern.  We know the pump pressure and GPH flow rate.  Based on that, if the rating is with the 5/16" fitting, it would be a moot point which fuel hose size you use.  The 4.6L inline six cannot burn more fuel than what we understand to be the flow ratings for your pumps.

 

As for 3/8" versus 5/16" hose flow rate, most concerns are on the pressure side, not the pick up side.  Here's a link that has considerable research information on pressure drop and its relationship to distance:  http://www.dultmeier.com/literature/fluid-flow.asp.  You might want to wade through this material, it does address hose sizing, too.

 

Note: Do take distance into account when sizing hose.  If you plan to run hose for a long distance on the pressure side, consider the larger size hose.  Also consider hose length when sizing the pick up side.

 

From a strictly practical standpoint, the use of 3/8" hose was popular on multiple carbureted engines in the muscle car era.  I've seen little use of that size hose for fuel supply on other production engine applications.  For peace of mind, take a moment to measure the OEM steel fuel pipes furnished with your Mopar EFI kit, the supply and return pipes that connect at the rail end.

 

Another consideration that you did not detail is the inside diameter of the furnished fuel pump fittings.  If these fittings are barbed or step nipples, I would be concerned about the I.D. of the fitting.  If the fittings are standard fuel type (clamp style) for 5/16" or 3/8" hose, then you should not have a restriction.  Hose size and flow volume take fittings into account: You can't have a hose installation without a fitting!  If the fitting I.D. is small, like a barbed fitting, I would step up the hose size to 3/8" and use the correct fitting for that size hose.

 

Better yet, you have fuel flow under scrutiny by continually monitoring the fuel pressure at the EFI fuel rail.  If you see fluctuations in the pressure, especially with a new regulator, you can suspect the fuel flow volume to the rail.  Volume reflects pressure and flow rate, so each will be apparent in the pressure reading at your shiny new fuel pressure gauge on the dash! 

 

Can't wait to see that fuel pressure gauge in service...What an onboard diagnostic tool!

 

Moses

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