E32-3 / MX-25 Fuel Bleeding Questions

[Kenneth K]

Fuel Bleeding Questions

I've had to bleed the fuel lines on my M-25 twice in the last month: Once after changing the engine-mounted fuel filter, and once after running it with the fuel SOV closed (I've graduated to the "those that will" camp). I'll need to bleed it again after I change the frame-mounted filter (I didn't have the part when I did the engine filter).

Question #1: Is it really necessary to bleed air from both the engine-mounted fuel filter housing and the fuel injector bleed ports. As they are only located a few inches apart, and, since the fuel injector bleed port is further downstream, it seem that bleeding air from just the FI port should suffice.

Second: Bleeding fuel lines can be messy. I caught some of the fuel in absorbent pads, but later had to clean the rest from the bilge. To minimize the mess, I stopped bleeding as soon as fuel exited from the port, even though there may have been more air trapped further up the line. Since fuel-line bleeding will be a recurring maintenance item, I had a thought: Can I replace the fuel injector bleed cap with a fuel shut-off valve and a fuel line to route the bled air and fuel back into the fuel return line (the line that carries excess, unused fuel from the injector housing back to the fuel tank)? I don't think the introduction of air into the fuel return line would cause any problems--it would wind up venting from the fuel tank.

Lastly, does anyone know the model number for Facet electrical fuel pump used in the 85 E32-3. I'm having trouble finding the model number on my unit.

Thanks,

Ken

 

[HerbertFriedman]

I just purchased a facet fuel pump from Yacht Supply Depot for my Universal 25XP, facet part number 476459E, for about $80.

 

[Loren Beach]

Getting that air out

Perhaps our M25XP engine is different, but our motor has a little knurled valve at the hi pressure pump. This is where the fuel line returns to the tank.
I open that valve and switch on (i.e. turn the key on) the engine circuit, which energizes the electric fuel pump. This visually pulls fuel thru the system and the bowel on the Racor. After a minute or two the fuel makes it back to the fuel tank via the return line. If I listen carefully I can hear the splashing of the fuel inside the tank.
Then I switch off, close that valve. Switch back on, glow plug, and it starts like normal.

Only distraction is the loud buzzing from the oil pressure alarm while the pump is clicking away, moving fuel thru.

Does your model have that bleed valve on the front starboard front side of the engine?

I found the manual on line and it does mention this valve. It also references other places to bleed the fuel, which I do not have to do on our later model.

"BLEEDING PROCEDURE:
Be sure to have some means available to catch or absorb any fuel escaping during the bleeding process so that it will not accumulate in the engine compartment or bilge.
1. Be sure there is a sufficient supply of fuel in the fuel tank.

2. Open the fuel shut-off valve at the tank.

3. Start the electric fuel pump by turning the ignition key to the "ON" position on models 18,
20, 25, 30, 50, all models after 1986.

4. Model 15 has a mechanical fuel pump. Therefore with decompression on, turn engine over with starter. Crank at 10 second intervals while doing steps #5 and 7.

5. Slowly loosen the air bleed plug on the fuel filter, letting air escape until an air free flow of fuel is evident. (1986 models see item 7).

6. At this time, tighten the air bleed plug on the filter.

7. Slowly loosen the air bleed plug on the injector pump, letting air escape until an air free flow of fuel is evident. Units with a self bleed return valve, open for a short period then start engine, as soon as engine runs smooth close valve. Model-12 has continuous fuel bleeding.

8. At this time, tighten the air bleed plug or knurled knob on the injector pump.

9. The fuel system should now be properly bled and ready for operation."


Regards,
Loren

 

[Kenneth K]

Herbert --- thanks, that's most likely the same pump as on my engine.

Loren --- I'll take another look when I'm out at the boat. Sounds like you might be describing the "self bleed return valve" referenced in Step 7 of the BLEEDING PROCEDURE. I don't believe I have this, and this is exactly what I was trying to achieve in my second question. Maybe the 25XP added it as an improvement. Sure would be nice......

 

[Kenneth K]

Brass Petcock for use as Fuel Shutoff Valve????

I'm gathering the parts I need to install a fuel self-bleed line to my M-25 engine. After cruising the aisles at WM and not finding what I needed, I collected some parts at the local Ace Hardware.

I found a great selection of brass pipe fittings and a brass petcock valve that might work for my installation. Is brass in general, and this type of petcock valve in particular compatible for use with diesel fuel? This is my fisrt foray into diesel mechanics.

The basic setup, as pictured, is very simple.

Thanks,

Ken

 

[HerbertFriedman]

just another question about the bleeding procedure. I dont think my 25XP has a self bleeding system because I do have a knurled knob at the base of the three fuel injector pipes. Some previous owner painted a red line on that knob indicating that is where you bleed the fuel system.

However when I try to bleed the system by unscrewing that knob nothing comes out, no fuel bubbles. I then loosened the nut which holds the knob onto the fuel manifold and I did get fuel bubbles, then finally a fuel flow and the system was bled. Question: is my knob clogged and if so how do I clear it? Unscrew it all the way and poke around with a "toothpick"?

 

[Loren Beach]

just another question about the bleeding procedure. I dont think my 25XP has a self bleeding system because I do have a knurled knob at the base of the three fuel injector pipes. Some previous owner painted a red line on that knob indicating that is where you bleed the fuel system.

However when I try to bleed the system by unscrewing that knob nothing comes out, no fuel bubbles. I then loosened the nut which holds the knob onto the fuel manifold and I did get fuel bubbles, then finally a fuel flow and the system was bled. Question: is my knob clogged and if so how do I clear it? Unscrew it all the way and poke around with a "toothpick"?

We have an M25XP. I open that petcock to let the fuel flow back to the fuel tank when "bleeding" the lines. If I listen very carefully (over the sound of the noisy buzzer back at the panel...) I can hear the fuel splash in the tank.
I wonder if that little valve is not working right on your engine? Given that it sees only well-filtered fuel, there's no way I can imagine it getting clogged.
AFAIK it's a little gate valve -- you unscrew it a ways to open it and screw it down firmly, but not too brutally, to close it.

Loren

 

[Kenneth K]

Herbert,

Like Loren says, you probably have the self-bleeding feature on your engine. Those without it don't have the knurled knob, but have a plug which must be removed with a wrench.

That's the beauty of the self-bleed feature--you're not supposed to see, hear, or smell, any air or need to clean up any fuel afterward. The knurled knob should allow the air and fuel to pass to the fuel return line, sight unseen; though as Loren said, if you put your ear near the fuel tank, you may hear the fuel trickling back into the tank.

Ken

 

[HerbertFriedman]

Ken and Loren, If I understand you correctly, turning that knurled knob opens a small valve which is the self bleeding feature and I should not expect to see any fuel coming out? Unfortunately my hearing, well it just plain stinks, so I may not hear the fuel splashing back into the tank. Is there any other indication as to when the system is bled other than just waiting? And after turning on the fuel pump (I have a remove switch) how long is usual for the system to be bled, tens of seconds??

 

[Christian Williams]

My one-person technique--not elegant, but it works:

1. With master switch off, turn on ignition in cockpit (electric fuel pump doesn't start).
2. Loosen bleed knob with tabbed baby diaper under it, secured by tabs.
3. Excite electric fuel pump by turning on nav station master switch.
4. When fuel spurts out wait a second or two, then turn off master switch to stop pump.

I would fill the Racor spin-on filter before installation, so the air bleed was pretty fast---only seconds sometimes.

With an empty Racor allow time for the pump to fill the filter, I imagine several minutes.

I could turn off the master switch with my toe whilst still holding the diaper on the engine. Learned that from an orangutan.

 

[HerbertFriedman]

Loren and Christian, now I am really confused. If the famous knurled knob is really just a way to open a small valve for the self bleeding system, then no diesel should come out of the knob. In the self bleeding system, as I understand it, there is a tube connected to the valve which brings the air bubbles and finally the diesel back to the tank.

In Christian's method, air bubbles and finally diesel come out of the knurled knob and it sounds like there is no valve and no tube going back to the tank.

I did rig a remote switch to turn on and off the ignition switch for the fuel pump so I dont need to get to the master switch and I do fill all the filters after a change so the bleeding time is fast. But I do get no bubbles nor diesel from the knurled knob so what I do is loosen the nut on the other side of the knurled knob until diesel comes out with no bubbles. But then the nagging question, why the knurled knob which clearly is meant that one does not need to loosen the nut behind it.

 

[Christian Williams]

Herb,

I think that if you have the simple knurled knob, then fuel comes out on your hand. At least that's the way mine was. The system was not set up for self bleeding.

But there is confusion about this "knurled knob":

http://c34.org/bbs/index.php/topic,5925.0.html

 

[Kenneth K]

My engine not having one, I'm a little confused about the knurled knob, too. Here's what it looks like without one. I must remove the plug with a wrench and bleed the air until I see (and hopefully catch) the fuel coming out. I can see why any owner might add a knurled knob if he didn't have one. It saves a trip back to the toolbox. I'd install a hose on the end, too, to catch the fuel.....now we're approaching minimal levels of automation.........

As for "How long to bleed the system:" As Christian said, if you've drained large amounts of fuel (such as that within a filter), it could take several minutes.

If you have it, and if you are using the "self-bleed" procedure, see step 7 in the instructions Loren posted above: ie, "Units with a self bleed return valve, open for a short period then start engine, as soon as engine runs smooth close valve."

Ultimately, if the engine starts and remains running smoothly, the system has been successfully bled.

Ken

 

[footrope]

Variations - Why?

This thread is confusing me, which should be no surprise to you regulars. My 5432 4-cylinder is plumbed with a hose from the knurled bleeder up to the first cylinder injector. See the orange and black arrows in the first attached pic.

Then the injectors are daisy-chained with similar hose. At the 4th injector the excess fuel return hose is attached and it runs back to it's own port in the top of the fuel tank. See the small red-black arrow at the top left corner of the second picture.

When I need to bleed the system after a filter change, I unscrew the knurled knob a few turns and flip on the electric fuel pump. I usually bleed the Racor and the spin-on filters first as described variously in the earlier posts and when I hear the return fuel trickling into the tank, it's done. This procedure does not bleed the injector lines that go into the top of the injectors, which is not usually required after a filter replacement anyway.

This seems like a slick arrangement and I wonder why all the Universals aren't configured this way?



Even this 1996 M-40, which is available for sale, has this feature:

 

[HerbertFriedman]

Knurled knob mystery solved, at least on my M25XP. Turns out I do have a thin, black rubber hose going from the base of the knurled knob to one of the fuel injectors, then joining the return fuel hoses back to the tank, so I do have the self bleeding system. Amazing how much you learn by asking silly questions.

One more silly question, when I do replace the diesel filters , I do refill with clean diesel and do loosen the bleed plug on at least the secondary (engine mounted) filter so it should not take too long to bleed my engine using the self bleeding knurled knob. But I am sure I will not be able to hear diesel splashing back into the tank so any idea how it takes to bleed the system?

 

[footrope]

Herb,
Cool. Self-bleeding is a term I learned last night when I queried a friend who has an M4-30 (in a Bristol 32) with the same configuration as I described above. So I have a self bleeder too. I would let the system pump for about 30 seconds after your last fuel filter has been bled of air. That should easily do the trick. Since the air in those daisy-chained fuel return lines isn't going anywhere but the tank, you can probably cut that shorter.

I have a 200-series Racor on the sidewall as a primary filter at 10 microns. I haven't really ever managed to get much air or fuel out of its bleed port after it fills up. So I don't bother with it. I bleed the spin-on 2 micron filter, as described by others, with the electric pump and the knob opened up and call it good.

Ken,
You have a Nippon Denso injector pump (most of us probably do). I can tell by the oval tag on the side opposite the bleed cap. If you carefully clean the paint off that tag you can get the model info and find out from your local injection pump servicing company whether you could retrofit a knurled knob and stick a fuel line on it that would go to the injector to make yours self-bleeding. You would need to buy an extra double port bleed thing (called an "eye joint") for that #1 injector. You could certainly rig up something of your own, too. If you can't find anyone to help with the injector info, I know a company in Seattle that services them and they can help. Let me know.

 

[Kenneth K]

Craig,

Great info. Thanks.

As I often find on this site, other people are two steps ahead of me. Your pictures had me re-thinking how to plumb a home-made self-bleed system.

I'm guessing the "eye joint" you mention is the part I circled in yellow. That would be the slickest way to plumb the bleed line (like Universal did).

I didn't know until seeing your pictures (as I'm assuming now) that each of those short, curved, horizontal hoses between the injectors is a return line. I only knew where my return line exited the engine after leaving the injectors. I'm now guessing I could Tee into any of those daisy-chained return lines for a bleed return (either of the yellow Tees above).

In an earlier post, you mentioned the frustration of so many variations in the Universal diesels. Interestingly, the picture I posted earlier of the M25 bleed cap was not from my boat, but from another boat I looked at: same boat, same engine, built only one year apart, and there are still variations. My bleed return line exits the front of the engine rather that the aft. This is my '85 M25:

It's kind of a natural setup to just Tee into the return line from the first (last?) injector, without adding another eye joint. I'll have to play with the configuration and post a picture of the final setup.

Thanks for the help,

Ken

 

[footrope]

Ken,
Yes, that is the eye joint you have circled. I looked for a picture of one all by itself, but I guess I never took a picture of the separate parts of the injector assembly.

I think you've got some good ideas for retrofitting a self bleeding configuration. It is interesting how an individual boat's arrangement drives differences in plumbing and wiring paths. Let us know how it turns out.

Cheers!

 

[Kenneth K]

Installing a self-returning fuel bleed line

This is the followup to an earlier post about replacing the fuel-bleed screw on an M25 injector pump with a "self-bleeding" valve and line. Self-bleeding is probably the wrong term; you still have to manually bleed the injector pump, after changing fuel filters, by running your electric fuel pump (though not the engine) until all the air is purged from the lines and filters. "Self-returning" is probably a better term in that, with the valve and line installed, you no longer have to catch the bled-off air and fuel in a cup or absorbent pads, it simply gets fed back to the fuel tank via the existing fuel return line. Here are the details:

The factory bleed screw on a Universal M25 is a metric M8x1.0 bolt (P/N 299748). Unlike normal pipe threads, it is not tapered, so it relies on a soft-metal (copper?) washer to form a seal with the bolt it threads into. The bleed screw actually has a hole bored all the way through it. Not sure why--I suppose if you could line the hole up properly, you might be able to bleed the pump without completely removing the bolt, by aiming the stream directly into a cup or something. Misalign it, though, or get fuel escaping around the threads, and you might get a face full of diesel fuel. Didn't want to try that one.

Later model M25XP's came with a self-returning bleed already installed. To convert an older engine, you could replace both the old bleed screw (above) and the bleed bolt (housing) that it screws into. The parts are:

#300050-Bleed Valve Assembly - $45, and #301936-Bleed Screw (Housing) - $22.

I tried to do it without buying these parts. I looked for an M8x1.0-to-1/8"NPT thread adapter so I could use my original bleed screw housing with off-the-shelf valves. I was never able to find the right combination. Instead, I had a machine shop tap out the top of my original housing bolt to 1/8 NPT. The guy charged me a half-case of Coors Light and has helped me out with other parts since then.

With the housing bolt tapped out to a normal pipe-fitting size, I just had to find the right valve. Interestingly, I found this on a go-kart website: http://bowmanenterprise.webs.com/apps/webstore/products/show/4527939 for $6.00. It's all-steel construction and seems to be well-made. I primed and painted it for corrosion protection. This screwed right into the newly tapped-out housing bolt.


The only other parts required were a standard 1/4 in tee-fitting, some 1/4" fuel hose, and 4 hose-clamps to plumb the line between the new valve and the existing fuel return line. My fuel return line comes off the front of the engine so I only needed about 4 inches of new hose. Many engines I see have the fuel return line coming off the back of the engine which would require a longer connection.




So, to bleed the fuel lines now, all I do is twist the bleed valve full-open and run the electric fuel pump for a few minutes. The bled-off air and fuel is then dumped into the return line (the line that exits the lower left corner of the picture) and ends up being dumped back into the top of the fuel tank. Should save a lot of time and clean-up come launch this spring.......

 

[GrandpaSteve]

Ken, if that is your engine in the picture, you should look into replacing the alternator bracket.
http://www.pbase.com/mainecruising/universal_alternator_bracket