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Conference unifix::sailing

Title:	SAILING
Notice:	Please read Note 2.* before participating in this conference
Moderator:	UNIFIX::BERENS

Created:	Wed Jul 01 1992
Last Modified:	Mon Jun 02 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2299
Total number of notes:	20724

1183.0. "Bleeding Diesel Fuel System" by BLAKLY::RADKE_HO () Mon Apr 24 1989 17:28

    I am about to replace all of the filters on the diesel fuel system
    of the Perkins 4.236 on our recently purchased sailboat. As I have
    no prior experience doing this type of thing I am looking for some
    advice. I have read the Perkins manual and it does emphasize that
    no air can be in the system, but it does not describe the techniques
    for doing this.
    
    The fuel system is as follows: From fuel tank to a Fram in-line
    filter (this looks like a gasoline type filter that might be on
    my car), to the Racor filter/water separator, to engine mounted
    filter/distribution unit.
    
    The surveyor recommended removing the Fram filter.
    
    The engine has a manually actuated pump that is used for bleeding
    the system. 
    
    The boat has had the fuel sitting in the tanks for about a year.
    The engine runs well, however both the Fram plastic filter and the
    Racor have a dark colored sediment in them.
    
    Thanks for your help.
    
    	Howard

T.R Title User Personal
Name Date Lines

1183.1 easy only after done many times MSCSSE::BERENS Alan Berens Mon Apr 24 1989 18:15 62

T.R	Title	User	Personal Name	Date	Lines
1183.1	easy only after done many times	MSCSSE::BERENS	Alan Berens	`Mon Apr 24 1989 18:15`	62
	Oh good grief, bleeding the fuel system on my diesel is only slightly more fun than being seasick. The first few attempts can be very frustrating. Remember that diesel engines have tender feelings. Shouting or swearing at them only makes them more uncooperative. First, I'd recommend draining the fuel tank. Diesel fuel that has been in the tank a year probably has water (from condensation) in it and possibly microbes or bacteria or whatever those things are that thrive in diesel fuel (unless you add the right stuff in the right quantity to inhibit their growth). Next, be sure all of your batteries are fully charged. You'll be cranking the engine a lot. Remove all of the filter elements, disassemble the filter bodies, clean, reassemble, and install new filter elements. This can be messy. An air compressor for blowing lines and other parts clean is very helpful. The manual lift on the fuel pump only helps bleed the parts of the fuel system between the fuel pump and the injectors. I connect a small, hand air pump to the vent fitting on my fuel tank and carefully pressurize the tank -- only a couple of psi are needed. The air pressure will force fuel (you did add new fuel after draining the tank, right?) through the lines and filters. The Racor filters are easy to bleed. Just loosen the top cover until the fuel level in the filter body reaches the top. The outlet on the Racor is well below the top, so a bit of air at the top is not a problem. There should be a bleed screw or plug at the top of the Fram filter. Remove it until fuel comes out and then reinstall. The filter on the engine (on our engine at least) is bled by loosening the topmost fuel line fitting. (You may need to talk to a Perkins dealer to find all of the bleeding points on the engine.) The remaining bleeding may not need to be done if you've just changed filters. If you've run out of fuel, you'll need to bleed them. They may also need bleeding if any air sneaks into the fuel system (as it has into ours). There is next a bleed screw on the injector pump -- location depends on the pump. On our pump there is a second cavity -- for the governor -- that must also be bled. (Dropping these screws or plugs under the engine or into the bilge is all too likely and most annoying.) Next bleed each fuel injector by loosening the proper fuel line -- the return line at the top of our injectors. You have to be cranking the engine to do the fuel injectors. The fuel here is under considerable pressure and just barely loosen the fittings. Now go back and bleed everything again. You'll know you're done when the engine starts and runs smoothly. It might be a worthwhile investment to pay a competent mechanic to show you how to do all this. Details vary from engine to engine. (A self-bleeding fuel system is a non-negotiable requirement when it comes time to replace our current engine.) Enjoy!

Oh good grief, bleeding the fuel system on my diesel is only slightly
more fun than being seasick. The first few attempts can be very
frustrating. Remember that diesel engines have tender feelings. Shouting
or swearing at them only makes them more uncooperative. 

First, I'd recommend draining the fuel tank. Diesel fuel that has been 
in the tank a year probably has water (from condensation) in it and 
possibly microbes or bacteria or whatever those things are that thrive in 
diesel fuel (unless you add the right stuff in the right quantity to 
inhibit their growth). 

Next, be sure all of your batteries are fully charged. You'll be 
cranking the engine a lot. 

Remove all of the filter elements, disassemble the filter bodies, clean, 
reassemble, and install new filter elements. This can be messy. An air 
compressor for blowing lines and other parts clean is very helpful. 

The manual lift on the fuel pump only helps bleed the parts of the fuel 
system between the fuel pump and the injectors. I connect a small, hand 
air pump to the vent fitting on my fuel tank and carefully pressurize the 
tank -- only a couple of psi are needed. The air pressure will force 
fuel (you did add new fuel after draining the tank, right?) through the 
lines and filters. 

The Racor filters are easy to bleed. Just loosen the top cover until the 
fuel level in the filter body reaches the top. The outlet on the Racor 
is well below the top, so a bit of air at the top is not a problem. 

There should be a bleed screw or plug at the top of the Fram filter. 
Remove it until fuel comes out and then reinstall.

The filter on the engine (on our engine at least) is bled by loosening 
the topmost fuel line fitting. (You may need to talk to a Perkins dealer 
to find all of the bleeding points on the engine.)

The remaining bleeding may not need to be done if you've just changed 
filters. If you've run out of fuel, you'll need to bleed them. They may 
also need bleeding if any air sneaks into the fuel system (as it has 
into ours).

There is next a bleed screw on the injector pump -- location depends on 
the pump. On our pump there is a second cavity -- for the governor -- 
that must also be bled. (Dropping these screws or plugs under the engine 
or into the bilge is all too likely and most annoying.) 

Next bleed each fuel injector by loosening the proper fuel line -- the 
return line at the top of our injectors. You have to be cranking the 
engine to do the fuel injectors. The fuel here is under considerable 
pressure and just barely loosen the fittings.

Now go back and bleed everything again. You'll know you're done when the
engine starts and runs smoothly. It might be a worthwhile investment to
pay a competent mechanic to show you how to do all this. Details vary
from engine to engine. 

(A self-bleeding fuel system is a non-negotiable requirement when it 
comes time to replace our current engine.)

Enjoy!