Yanmar starting question - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #11  
Old 04-18-2009
Senior Member
 
Join Date: May 2007
Posts: 551
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
This is such a common question that I think it deserves a sticky thread or faq. I'm sure the following text could be improved, but I think it's a good start.

You need to be able to identify a few parts of the fuel system. Follow the fuel hose from the primary filter (often a Racor) to the engine. First, the hose goes to the low-pressure fuel pump (also called a lift pump). On a Yanmar this will be a mechanical pump. Then follow it to the secondary fuel filter, which is attached to the motor. From there find the fuel line that goes to the high-pressure fuel pump. So far you have traced the low-pressure fuel system. (If you are having trouble finding the high-pressure pump you can trace the metal fuel lines back from the injectors.)

If you introduce air into the low-pressure fuel system, for example, change the fuel filters, you should bleed the air from the low-pressure system before trying to start the motor. If you ignore this advice you will force air into the high-pressure system and then you have to bleed that as well. Also, when changing filters, do not fill the filter with fuel before reinstalling it.

To bleed the low-pressure system open the vent on top of the secondary filter bracket until you can see the hole in the side of the threads. Find the low-pressure fuel pump and operate the small lever on its side. Only the last ˝ inch of travel pumps the fuel. Move the lever back and forth until clear fuel comes out of the vent screw on the filter. This will take many strokes if the filters have been replaced. (Use a cup or a rag to catch the fuel coming out of the bleed screw.) When you have good clear fuel with no bubbles, close the screw. If operating the lever pumps no fuel (there is no resistance operating the lever) you may have to turn the engine over a tad (with the kill switch out). This will move the pump cam off the lever. Then find the inlet into the high-pressure pump. The hose comes from the secondary filter. Loosen the banjo bolt a number of turns, and then once again operate the lever on the fuel pump. It should only take a few strokes to get clear fuel at the high-pressure pump inlet. Then tighten the banjo bolt. The low-pressure system should not be air free.

The high-pressure system consists of the high-pressure fuel pump, the fuel lines going to the injectors, and the injectors. Normally you do not need to bleed the high-pressure system after changing filters, just the low-pressure system.

Bleeding the high-pressure system goes like this....

Bleed the low-pressure system first. Then, open the connection at each injector 1 full turn (open all of them). Turn the key on and crank the engine over until fuel spits from the loosened connectors. Do not pull out the kill switch! The engine cannot start like this so don't worry. Then firmly (these things run at 2,000 - 3,000 psi) re-tighten each injector connection. There is no hurry, the fuel cannot “leak-back” while you are doing this step. That's it - start it up! (If it doesn't start, bleed the low-pressure system again, and then the high pressure system.)
Reply With Quote Quick reply to this message Share with Facebook
  #12  
Old 04-19-2009
BarryL's Avatar
Senior Member
 
Join Date: Aug 2003
Location: Long Island, NY
Posts: 1,650
Thanks: 3
Thanked 29 Times in 28 Posts
Rep Power: 12
BarryL is on a distinguished road
Hi Nick,

If you engine runs fine, you don't have a problem with air in the lines. If you do have air in the fuel line, the engine won't start until the air is bled out. Since your engine does start, runs, and keeps running, bleeding won't do anything.

It is possible that you don't have a good seal somewhere in the fuel lines, and when the engine is shut down, air gets in. Take a look at the things you touched, make sure you got all the gaskets installed properly. When the engine is running, look for fuel leaks, that is one way to know if a gasket is bad.

Lastly, the pressure gauge is most likely a vacuum gauge. As the fuel filter gets dirty, it requires more and more suction to draw fuel through it. This will be shown on the vacuum gauge and will let you know that it's time to change the fuel filter.

One final point, there are many many boaters who would LOVE to have their engine start in 5-7 seconds. On my boat, when it's cold (below 60), I need to energize the glow plugs for 30 - 60 seconds, then crank the engine for at least 10 seconds before it runs. So maybe, as another poster mentioned, it's just too cold.

Good luck,
Barry
__________________
Barry Lenoble
Deep Blue C, 2002 C&C 110
Mt. Sinai, NY

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message Share with Facebook
  #13  
Old 04-19-2009
Senior Member
 
Join Date: May 2007
Posts: 551
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
Well obviously people disagree on this one. I still believe you have a small air leak. Hence the extra cranking after the engine sits. Here's how to test the theory. After letting the engine sit, bleed the system before trying to start it. If it fires right up after bleeding it, you have an air leak. If there is no change and it still requires the extra cranking time, you don't.
Reply With Quote Quick reply to this message Share with Facebook
  #14  
Old 04-19-2009
nk235's Avatar
Senior Member
 
Join Date: Apr 2007
Location: Long Island
Posts: 404
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
nk235 is on a distinguished road
SteveNMD - Thanks very much for the detailed post on how to bleed the system. How come you don't have to bleed the secondary fuel filter (racor) before going to the primary on the engine? Also why don't you recommend putting fuel back into the filters after changing them?

Barry - Thanks as well - I am hoping it is just a cool air thing because it does start right back up after it has been running.

I guess either way I will find out but thaks again for all the help everyone
__________________
Morgan 323
Reply With Quote Quick reply to this message Share with Facebook
  #15  
Old 04-19-2009
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
BTW, over-tightening banjo bolts is a common cause of air leaks into a fuel system... so replacing the banjo bolt compression washers can often fix it...if you don't over tighten them..
Quote:
Originally Posted by bubb2 View Post
Bleed at the banjo bolt on top of the injector. Open the bolt a little and pump. If you see foam you have air. When you pump and see just fuel the air is gone. You can also bleed at the top of secondary filter. The little bolt right on top.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Quick reply to this message Share with Facebook
  #16  
Old 04-19-2009
Senior Member
 
Join Date: May 2007
Posts: 551
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
Quote:
Originally Posted by nk235 View Post
SteveNMD - Thanks very much for the detailed post on how to bleed the system. How come you don't have to bleed the secondary fuel filter (racor) before going to the primary on the engine? Also why don't you recommend putting fuel back into the filters after changing them?

Barry - Thanks as well - I am hoping it is just a cool air thing because it does start right back up after it has been running.

I guess either way I will find out but thaks again for all the help everyone
Actually the Racor is usually referred to as the primary filter. You don't have to bleed this first because in a "normal" setup you have to suck the fuel through it using the low-pressure pump. Unless the primary filter has a built-in hand pump there is no way to bleed it by itself. The built-in pumps are nice, but not necessary at all.

The reason not to fill the filters first is because it can cause air to be forced into the high-pressure system. I can't tell you how many times I've seen this happen... You change the fuel filters and topping them up with fuel to avoid so much manual pumping. Then you start the bleeding process. However since there is clear fuel in the hose from the Racor thought the lift pump and up to the secondary filter (the one attached to the motor) you get clear fuel spouting from the vent screw very quickly. Happy with your brilliant idea to pre-load the filters you move on to the next bleed point at the high-pressure pump inlet. Again, a few strokes and you think you are done so you button everything up and fire the up the engine. It starts right up and you smile proudly. After about 5 minutes of running the engine sputters and quits. What happened is that there was a big slug of air in the top of the Racor (even though you mostly filled it). This slug of air travels through the system and ends up in the high-pressure side, which is when the engine quits. Now you have to start from square one and bleed the low side and then the high side. I find it easier to just stick to the procedure pump the lever as needed. Yes, you can pre-fill a little fuel, without causing problems, but I don't think it's worth the trouble.

Regardless if you are having problems with air in your fuel system or not at the moment it's good to know how to bleed the system. Practice in your slip so you can do it easily at sea.
Reply With Quote Quick reply to this message Share with Facebook
  #17  
Old 04-19-2009
Senior Member
 
Join Date: Jul 2008
Location: 34.25n 119.27w
Posts: 403
Thanks: 1
Thanked 4 Times in 3 Posts
Rep Power: 7
SJ34 is on a distinguished road
nk235, does your fuel system leak? If not, you probably don't have an air leak.

You have not mentioned what the fuel flow was like when you bled the secondary filter (the 2 micron filter at the engine) with the lift pump.
Sometimes, when the lift pump starts to lose performance, the engine will be slow to start at first but on subsequent starts it will fire right up. Until it has a chance to sit and lose the prime again. Once fuel is flowing to the high pressure pump it will draw fuel on it's own. On older engines, the bottom of the lift pump had a weep hole that would leek if the pump diaghram went bad. CG regulations outlawed those types of pumps so now the system is closed and won't leak or draw in air that kills the engine when the pump is bad.

I'll go along with what's been said earlier. If your lift pump is working (you get good strong squirts when bleeding from the banjo on top of the filter) and you are getting clear fuel when bleeding, there is probably nothing wrong and the slow starting is normal for the season.

For the record. I would still prefill the Racor. If you don't, all of the air volume in that filter will have to be bled at the secondary, with the lift pump which does not have much flow volume. If you are concerned about air in the fuel lines during filter changes, either install valves or mount the filter in a slightly elevated position so the fuel doesn't run out of the hoses when you drain the Racor bowl.

Most of my fuel system is mounted below the top of the fuel tank. Before I open the fuel system I just make sure the tank is topped off so I can gravity bleed before I bleed the engine with the pump.
Reply With Quote Quick reply to this message Share with Facebook
  #18  
Old 04-19-2009
timebandit's Avatar
Senior Member
 
Join Date: Sep 2002
Posts: 928
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 13
timebandit is on a distinguished road
Rule #1
__________________
Rick
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Mac 25
Copernicus
Southern California
I am not a prejudice racist sexist bigot. I just hate stupid people.
Reply With Quote Quick reply to this message Share with Facebook
  #19  
Old 04-19-2009
L124C's Avatar
Senior Member
 
Join Date: Oct 2007
Posts: 1,388
Thanks: 48
Thanked 3 Times in 3 Posts
Rep Power: 8
L124C is on a distinguished road
Quote:
Originally Posted by Gary M View Post

If you engine starts and runs fine for say 15 minutes or so then I would think you do not have air in the lines.

Another thought you could have an air leak, check all you connections.

Gary

On my 2GM it takes a lot longer than 15 minutes at 1000 to 2000 RPM to run air through the system. Closer to 30 to 40 minutes. Hard to believe, but I learned the hard way!
Reply With Quote Quick reply to this message Share with Facebook
  #20  
Old 04-19-2009
Senior Member
 
Join Date: May 2007
Posts: 551
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
Quote:
Originally Posted by SJ34 View Post
nk235, does your fuel system leak? If not, you probably don't have an air leak.

....Until it has a chance to sit and lose the prime again.
The only way to lose the prime is if you have an air leak.
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need help YANMAR engine mount Giulietta Gear & Maintenance 20 04-15-2010 02:15 PM
Yanmar 4JH2E air filter element garyroot Gear & Maintenance 8 03-30-2010 09:23 PM
Starting Battery - Yanmar 3GM JohnRPollard Gear & Maintenance 14 03-11-2008 01:31 PM
Yanmar - fuel injection pump question rperret Gear & Maintenance 7 05-24-2007 11:00 AM
Yanmar 4JH air filter k1vsk Gear & Maintenance 19 12-25-2006 02:17 PM


All times are GMT -4. The time now is 08:17 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.