Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-04-2016, 03:51   #61
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,748
Re: Air in Fuel System -- Yanmar

Quote:
Originally Posted by petter5 View Post
Be sure to correctly size your fuel lines and filters, using good quality material.

One thing I have seen several times is fuel tanks with suction pipes threaded in the tank cover leaking air in the threads , can be extremely difficult to diagnose.

One thing that would not fix the system, but fix the symptoms is to mount a so called "Tiger loop" to remove the air from the fuel:
Tigerloop Article

The works fine for boat engines as well :-)
I'm starting to suspect something like this.

We'll see. The next step is to obtain and fit the correct hose tails, and buy new sealant. I'll check the sensor for cracks or air leaks.

If that doesn't work and the same symptoms appear, then I'll splice in a piece of clear hose between the sensor and Racor to see if there are any bubbles in the fuel.

If there are no bubbles there, then I'll move the clear hose to after the sensor.

If there are no bubbles there, then I'll move the clear hose to between the secondary filter and the pump.

If I can't find any bubbles anywhere, then I'll know it's because the system simply doesn't like the resistance of the sensor (which I feel is unlikely), in which case I'll add a Facel fuel pump between the Racor and the sensor.


Does that sound like a plan?
__________________

__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 18-04-2016, 04:03   #62
Registered User

Join Date: Oct 2011
Location: Canada
Boat: CT 56
Posts: 418
Images: 3
Send a message via Skype™ to undercutter
Re: Problem Solved

Quote:
Originally Posted by Dockhead View Post
As soon as I had the proper fuel hose, I tried running the engine from a fuel jug via a direct hose to the secondary filter. Bingo. Ran perfectly.

So quickly bypassed the supply side fuel flow sensor and -- bingo.

Runs like a Swiss watch, smooth and sweet, right up to 4000 RPM.


It turns out that I bought the wrong nipples for the fuel flow sensors -- for 3/8" fuel hose rather than 8/16 (5/16"). That's why it was so hard to get the hose onto the nipples -- wasted two extremely unpleasant evenings wrestling the hoses onto the wrong nipples -- with one hand.

Now I did get them on, so why this would cause this problem I don't know. I have ordered new nipples and will try again in a few days. My guesses:

1. Somehow stretched or split the hoses to cause an air leak
2. The nipple leaks where it's screwed into the sensor (I used thread compound, but it was kind of old -- maybe didn't work).
3. Crack or other defect in the sensor
4. My engine just doesn't like the resistance created by the sensor.


In any case, boat is again seaworthy (hurra!), and the rest I'll figure out in a few days when the new nipples come.

Thanks everyone for the whole education on fuel systems! The only bright side of this horrendous waste of time, is that I've learned an awful lot about fuel systems.
I would try running the engine out of the gerry can with the fuel sensor spliced in ahead of the lift pump maybe before hooking it all up permanently, Would hate to take it all apart again if you found out that the sensors were in fact causing enough restriction to cause your problems especially as it sounds like such a pain to get at everything.

Fuel line size is usually specified in the installation manual for the engine and even the return line size is critical to proper operation.

I agree that this didn't sound like an air problem.

Sometimes soaking the hose in boiling water helps expand and soften things but I sure you would have tried that if there was room to work.
__________________

__________________
undercutter is offline   Reply With Quote
Old 20-04-2016, 22:15   #63
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jun 2010
Location: Mediterranean
Boat: Beneteau Oceanis 50
Posts: 282
Re: Air in Fuel System -- Yanmar

Quote:
Originally Posted by Dockhead View Post
I'm starting to suspect something like this.

We'll see. The next step is to obtain and fit the correct hose tails, and buy new sealant. I'll check the sensor for cracks or air leaks.

If that doesn't work and the same symptoms appear, then I'll splice in a piece of clear hose between the sensor and Racor to see if there are any bubbles in the fuel.

If there are no bubbles there, then I'll move the clear hose to after the sensor.

If there are no bubbles there, then I'll move the clear hose to between the secondary filter and the pump.

If I can't find any bubbles anywhere, then I'll know it's because the system simply doesn't like the resistance of the sensor (which I feel is unlikely), in which case I'll add a Facel fuel pump between the Racor and the sensor.


Does that sound like a plan?
Check that the main pipe drawing fuel from the fuel tank (before the Racor filter) is not blocked. Some have a gauze filter which can collect material and restrict sucking of fuel from the tank. A quick check. After the engine dies, spin the top off your Racor, if you hear a suction hiss as you release the top of the Racor then you have a blockage in the tank...
__________________
lordgeoff is offline   Reply With Quote
Old 21-04-2016, 00:18   #64
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,748
Re: Air in Fuel System -- Yanmar

Quote:
Originally Posted by lordgeoff View Post
Check that the main pipe drawing fuel from the fuel tank (before the Racor filter) is not blocked. Some have a gauze filter which can collect material and restrict sucking of fuel from the tank. A quick check. After the engine dies, spin the top off your Racor, if you hear a suction hiss as you release the top of the Racor then you have a blockage in the tank...
Good tip. I'll keep it in mind for the future.

Sent from my D6633 using Cruisers Sailing Forum mobile app
__________________

__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Reply

Tags
fuel, yanmar

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:06.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.