Fuel Filter Primer

[britinusa]

There's sediment in our Fuel Water Separator (Racor) using R12S 2mic filters.

I have not changed the fuel filter since installing the new filter unit 6 months ago.

It may be time to clean out the fuel tank, but for now I need to replace the filter.

The process requires that I 'prime' the filter by filling with fuel before screwing it back on the filter housing.

I'm wondering how others do that!

Should I keep a small bottle of diesel fuel onboard that I can use to prime the filter, or should I install a primer pump, or even a simple bleed off the main fuel line before the filter unit.

What do you guys do?

Paul

[KWKloeber]

 Paul

Although I have never needed to prime my recorder when changing it, that's one of the benefits of how I have my bleed set up  on my M 25. When I upgraded the bleed screw to the newer bleed knob, as on the XP, I  left the fuel lines as they were. I did not  run the bleed knob barb to the  return line to the tank.

That way I can grab a sample of fuel anytime.

Or while bleeding the lines, I can absolutelyf tell when the air is out and there's no foam. Plus I like being able  to catch the bleed in a plastic cup, to "see" my fuel quality.   i'm sure it's a false sense of security,  though .   LOL

kk

[britinusa]

Ken, thanks.

I have the bleed screw on my M25-XP cracked open which I also understand is supposed to continually bleed the fuel lines by returning fuel/air back to the tank.

On my boat, the fuel line is: Tank > Fuel Shut Off valve > Racor 2mic Filter > Fuel Pump > Engine mounted fuel filter > Injector pump.

My understanding is that the fuel pump will not pump because it needs priming. So I was reluctant to change out the fuel filter yesterday at the dock. My concern is that if I were at sea and needed to change the filter, then I would need a way to prime the filter.

When I installed the new Racor filter unit, it would not prime because I did not fill the filter with fuel prior to screwing it back into the fuel filter housing. At that time, I simply poured some diesel into a jar from a 5gal Jerry can and used that to prime the filter. A messy solution.

I was thinking of adding one of These (Link) inline.

Paul

[Stu Jackson]

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My understanding is that the fuel pump will not pump because it needs priming. ...........................
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Not true.

Have you read the "Bleeding 101" topic?

It simply takes a tad longer if your filter is empty.  The pump gets primed when you open the fuel shut off valve.

I have a bunch of injector cleaner I pour into the filter when I change them, no messy diesel sloshing around.

[KWKloeber]

 Paul,

Yes your sequence is the same as mine, but of course I have a c 30. My understanding is, that fuel flows more freely, on the C 34 and thus the low oil pressure/fuel pump shut off on the xpb  and 35b engines really doesn't work. I have no knowledge whether it actually works on the c 30.

Have you tried bleeding/starting the engine without priming the  Racore, as I said I've never had an issue (knock on  teak. ). 

Yeah, I've read  on here about needing to keep the bleed  partially  open, but I really don't understand why that would be. Obviously it's the same engine as the M 25 and OEM was a bleed screw not bypassing to the return line.   I  understand that some do need to leave the XP setup  cracked open, but the  explanation  for that I don't know, and it may very well be one of those some do  need to, some don't  need to, who knows why, voodo.    The only difference fuel wise between the M 25 and XP is that on the M 25 the return line tees into the  fuel  banjo on the number one injector, and on the XP it tees into the banjo on the number three injector.   I haven't really thought about it but at first blush I don't see why that would necessitate leaving the bleed/bypass  cracked open?

kk

[KWKloeber]

Injector cleaner. D'oh. What a great idea!!!

[britinusa]

Injector cleaner. D'oh. What a great idea!!!

Duh! and I keep several bottles of that aboard. I add 1/5th of a bottle for each 5 gallons of fuel.

That sounds like a KISS solution (pun intended) 

Paul

[Ron Hill]

All : The bleed screw is on the bottom bowl of your Racor for a reason. 
You can simply take a sample of the fuel into a glass container and see water droplets and /or sediment.  Then retighten that screw.

On the first flight of the day all aircraft tanks are bleed into a glass jar for the reasons mentioned above!!

A thought     

[britinusa]

Thanks for that post Ron,
The new Racor that I installed last September has the clear bowl so we can check for water/sediment without removing it. It also has the drain and that would normally be our first choice of action.

The issue of priming the fuel pump only came up while thinking the process of changing out the filter while at sea.

Paul

[Jim Hardesty]

The new Racor that I installed last September

Paul,
If your Racor is like mine it has a primer pump built in.  Loosen a knob on top, pull it up and pump.  It does take a bit of pumping but it does work.  Better if the tank is near full.
Jim

[Stu Jackson]

The new Racor that I installed last September

Paul,
If your Racor is like mine it has a primer pump built in.  Loosen a knob on top, pull it up and pump.  It does take a bit of pumping but it does work.  Better if the tank is near full.
Jim

Jim & Paul,

I did that once, in 1999, and my fingers STILL hurt!!!

Look, fellas, that's WHY the fuel pump is there in the first place.  Please, save yourselves a lot of work and just use it.   

For those of you with the "newer" electrical setup that requires you to energize the glow plugs to get the fuel pump going, please read Critical Upgrades again, and install the bypass wiring scheme to run the fuel pump "around" without using the glow plugs to bleed your system. (I think that's what Ken was referring to.)

[KWKloeber]

install the bypass wiring scheme to run the fuel pump "around" without using the glow plugs to bleed your system.

Hi Stu,

I searched and can't seem to find the sticky CI topic about installing a bypass wiring scheme -- I presume you're referring to a switch to run the pump on the XPB/35B w/o needing to energize the preheat solenoid?  I've searched and found a few leads that seemed promising, but didn't pan out.

Can you provide a "starting" (ugggggg) point?

(I think that's what Ken was referring to.)

Not sure exactly what "you are referring to that I was referring to,"  but:

If it's re: the B-series engines, I was not referring to a "bypass" so to speak -- just made the point that the supposed safety feature (killing the fuel pump) on the B-series doesn't kill the engine.  I have no knowledge if it that concept works on other manufacturer installs.  Maybe it depends on the relative elevations of the tank/engine? 

If it's re: the bleed bypass?  I was just referring to posts on here that (some?) say they must leave the XP bleed knob cracked open for the engine to run smoothly.

PS: Loosely related --
I purchased (yet to install) a double pole/double throw switch, i.e.:  ON - OFF - Momentary ON
to install a bypass switch below to power the fuel pump (for bleeding) and crank the starter (for troubleshooting.)  I'm thinking I may get another Mom-On switch for preheat also.

-ken
(M-25)

Did you see my last note about the C30 "wiki"?

[Noah]

The bleed screw on my 25XP is open ALL THE WAY and the engine runs just fine. Caveat: I AM NOT A MECHANIC and may be off base, but as I understand it, this serves as a poorman's fuel polisher, sending bypass fuel back to tank and keeps recitculating through my 500 series Racor turbine filter for more frequent filtration.

Also the way the ignition key is wired on the 25XP (mine anyway) is it is a three position switch
1. Off
2. One click clockwise turns on fuel pump
3. Turn clockwise all the way and hold, energizes glow plugs.
4. Release switch, push start button and VAROOM

[Dave Spencer]

Ken,
Here is a starting point for an old discussion on this subject.  It is a long and convoluted rabbit hole but there is excellent information in this link and a prior post that Stu refers to.
http://c34.org/bbs/index.php/topic,6429.msg41828.html#msg41828

Noah,
Oh how I wish my system worked that way!  On my boat, the first click does not energize the fuel pump unless the oil pressure switch senses oil pressure and of course there will be none if the engine isn't operating.  Apparently, the logic (albeit flawed logic) behind this is that if you lose oil pressure, the fuel pump shuts off and the intent is the engine will shut off.  Unfortunately, if you have a reasonable amount of fuel in the tank, the fuel will flow freely without the pump running so this "built-in save the engine" feature doesn't work as intended (at least on my boat and I think many others).  I need to click it over to "Glow" to get the fuel pump working.  Since it is unwise to keep the glow plugs energized for a lengthy period (long enough to bleed the fuel lines), I have a small "U-shaped" piece of wire that I use to bypass the oil pressure switch when I want to operate the fuel pump only.  On my M35AC engine, the oil pressure switch is accessible on the port side of the engine behind the oil filter.  A more elegant way would be to modify the wiring so it operates as Noah's does or install a switch but in the rare cases when I need to bleed my lines, the jumper wire works fine for me.  I have not had any need to use the thumb pump on the Racor - thank goodness.  Simply energize the fuel pump, crack open the thumbscrew on the bleed valve and the engine is ready to go in a few minutes. 
I agree with Noah that leaving the bleed screw open serves as a fuel polisher.  I don't do it on mine because I get a very small drip of fuel around the bleedscrew shaft when it is open... likely a bad seal.  I hope to replace the bleed valve (Kubota part?) at some point to allow me to operate as Noah does. 

[Stu Jackson]

Hi Stu,

1.   I searched and can't seem to find the sticky CI topic about installing a bypass wiring scheme ......
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Can you provide a "starting" (ugggggg) point?



2.   Not sure exactly what "you are referring to that I was referring to,"  but:

If it's re: the B-series engines, I was not referring to a "bypass" so to speak -- just made the point that the supposed safety feature (killing the fuel pump) on the B-series doesn't kill the engine.  I have no knowledge if it that concept works on other manufacturer installs.  Maybe it depends on the relative elevations of the tank/engine? 

If it's re: the bleed bypass?  I was just referring to posts on here that (some?) say they must leave the XP bleed knob cracked open for the engine to run smoothly.

3.   PS: Loosely related --
I purchased (yet to install) a double pole/double throw switch, i.e.:  ON - OFF - Momentary ON
to install a bypass switch below to power the fuel pump (for bleeding) and crank the starter (for troubleshooting.)  I'm thinking I may get another Mom-On switch for preheat also.

-ken
(M-25)

4.   Did you see my last note about the C30 "wiki"?

1.  In addition to Dave's wonderful discussion here, this is the CU topic:

http://c34.org/bbs/index.php/topic,5078.msg41829.html#msg41829

Gee, Dave, you're the guy who started all this!!!

2.  I should not have used the word bypass for the wiring.  The links here explain it all, I'm tired of repeating it all.    Lazy b*stard that I am...   It's not the bleeding, it's the wiring from the ignition switch, the glow plugs and the fuel pump.  I have been pointing this out ever since Michael's post in 2007, which would be how many years ago???

3.  Why bother?  With an M25 you should simply be able to run the fuel pump from the cockpit ignition switch.  For bleeding the secondary engine mounted filter I added a fuel pump shutoff switch as explained elsewhere.  Beats hustling up to the cockpit to turn it off when the fuel starts shooting out of the filter bracket nut on the secondary.  That's all I've ever needed in 18 years.  I "get" the started thing, but why bother, just go up to the cockpit, 'cuz once the fuel pump ticking stops, you're done and the engine WILL start, at least always has for me.  This is all discussed in great detail in Ken Heyman's great Bleeding 101 topic.

4.  Yes, Ken, I did, but what more is there to say, other than I'm sorry your great efforts didn't take hold with Mad Max?