Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-29-2017, 03:52 PM   #1
Veteran Member
 
City: Shelter Bay
Country: United States
Vessel Name: Little Missy
Vessel Model: CHB
Join Date: Jul 2015
Posts: 72
Fuel return

I have a 1976 120 Lehman in my 1976 CHB. Can anyone tell me approximately how much fuel gets returned to the tanks at about 1750 rpms?
Thanks
__________________
Advertisement

Island15 is offline   Reply With Quote
Old 05-29-2017, 04:03 PM   #2
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,844
At 1650, mine was returning so little, I got tired of waiting for the drops to show up.

My return lines feed right back into the supply lines in front of the primary filters.
__________________

psneeld is online now   Reply With Quote
Old 05-29-2017, 04:11 PM   #3
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 5,528
Lehmans return almost no fuel. Bob Smith said it may return about a pint in a day's cruise.
Comodave is online now   Reply With Quote
Old 05-30-2017, 02:25 PM   #4
Senior Member
 
ksceviour's Avatar
 
City: North West Basin
Country: Canada
Vessel Name: Moderation
Vessel Model: Sea Lord 35
Join Date: Aug 2016
Posts: 147
Hmm, interesting. I wonder how much the Perkins 6.3544 returns?
ksceviour is offline   Reply With Quote
Old 05-30-2017, 03:53 PM   #5
Guru
 
Sealife's Avatar
 
City: In transit
Country: From USA
Vessel Name: Sea life
Vessel Model: Krogen 42 #61
Join Date: Nov 2013
Posts: 531
Alot more. My '82 mainship had that motor, I could balance the boat in a days run due to return volume. My FL120 seems completely insignificant, although this boat is much heavier, wider, etc.
__________________
Scott

www.caribbeansealife.com
Sealife is offline   Reply With Quote
Old 05-30-2017, 03:56 PM   #6
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 5,528
I had twin 6V53s in a previous boat. They returned way more than they burned. It did keep the fuel polished somewhat. In a way that is not good with the Lehmans.
Comodave is online now   Reply With Quote
Old 05-30-2017, 08:09 PM   #7
Guru
 
City: Full Time Cruising East Coast
Country: USA
Vessel Name: Meridian
Vessel Model: Krogen-42
Join Date: Aug 2011
Posts: 988
Returning fuel is also a way to keep the injector pump cooler
__________________
-------------------------
Terry
Meridian
KK-42097
meridian is offline   Reply With Quote
Old 05-30-2017, 08:13 PM   #8
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,844
Ok..but the question was answered and other engines are diffetent.....doesnt mean the return on a Lehman is detrimental.
psneeld is online now   Reply With Quote
Old 05-31-2017, 08:16 AM   #9
Veteran Member
 
City: Shelter Bay
Country: United States
Vessel Name: Little Missy
Vessel Model: CHB
Join Date: Jul 2015
Posts: 72
Ok, thanks for all the input "BUT" I must have some other problem here goes!

I don't have fuel gauges just a really nice stick. I filled both tanks to with-in about 2" of full. My fuel system only returns to one tank (starboard), it also has an electric fuel pump. I was concerned that because it only returned to one tank that a should use some fuel from that tank first.

After running about 7 hours the boat was listing to the port side I measured the tanks with my custom stick and port tank was still about 2" down as is was turned off the starboard tank was down about 5".
So I switched to both tanks ran about 7 more hours when I stopped fuel was coming out of the over flow on the starboard tank!

Using the custom stick I re-measured the tanks, port down about 5" starboard full to the top!

Any ideas would be great!

Sorry for the long post
Island15 is offline   Reply With Quote
Old 05-31-2017, 08:23 AM   #10
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,844
Is there a bypass on the fuel pump to the return?


Or just the single line from electric pump to injection pump?
psneeld is online now   Reply With Quote
Old 05-31-2017, 08:28 AM   #11
Veteran Member
 
City: Shelter Bay
Country: United States
Vessel Name: Little Missy
Vessel Model: CHB
Join Date: Jul 2015
Posts: 72
Fuel pump to filter.
Island15 is offline   Reply With Quote
Old 05-31-2017, 08:31 AM   #12
Veteran Member
 
City: Shelter Bay
Country: United States
Vessel Name: Little Missy
Vessel Model: CHB
Join Date: Jul 2015
Posts: 72
One more thing, there is a line out of the top of the filter housing that goes to the return line!
Island15 is offline   Reply With Quote
Old 05-31-2017, 09:20 AM   #13
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 5,323
I don't think all Fords/Lehmans are plumbed the same. Last one I had in my shop for a rebuild I bench ran it and if I remember right it had a fair amount of return flow.

It's normal practice in the diesel world to have a drilled orifice or pressure control valve from injector pump to return. If you don't have that, it will not naturally purge air and can lead to stalling. On other engines like that (Yanmar GM) I have custom made a bleed rig to the return to get rid of the air problem.
Ski in NC is online now   Reply With Quote
Old 05-31-2017, 09:35 AM   #14
Veteran Member
 
City: Shelter Bay
Country: United States
Vessel Name: Little Missy
Vessel Model: CHB
Join Date: Jul 2015
Posts: 72
So if I take the return line off the top of the tank where it currently returns and just "T" it into the supply line before the fuel pump will that cause any problems?

Thanks for the help!
Island15 is offline   Reply With Quote
Old 05-31-2017, 10:07 AM   #15
Guru
 
psneeld's Avatar
 
City: AICW
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 19,844
Depends on the electric pump.

Might be better to tee it with valves to select the return to the same tank you are drawing from.
psneeld is online now   Reply With Quote
Old 05-31-2017, 11:46 AM   #16
Guru
 
Comodave's Avatar
 
City: Au Gres, MI
Country: US
Vessel Name: Never Say Never
Vessel Model: President 41 DC
Join Date: Jul 2015
Posts: 5,528
I took Bob Smith's class on the 120. We worked on it and then started it up. I don't recall that we even hooked up the return to the fuel tank. But we only ran it for about 15 minutes.
Comodave is online now   Reply With Quote
Old 05-31-2017, 12:14 PM   #17
Guru
 
LarryM's Avatar
 
City: League City, TX
Country: USA
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 921
Island15

It sounds like you may be a candidate for a Groco 6 Port Fuel Valve.



This switches both the supply and return with a single lever and will permanently prevent the overflow you experienced. One valve, one handle, easy peasy
__________________
Larry
M/V Pelago
LarryM is offline   Reply With Quote
Old 05-31-2017, 01:20 PM   #18
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,436
Quote:
Originally Posted by Island15 View Post
One more thing, there is a line out of the top of the filter housing that goes to the return line!
That bleeds off any air that might get in the system before the filters and helps prevent the injection pump from getting air locked.
Capt.Bill11 is offline   Reply With Quote
Old 05-31-2017, 01:50 PM   #19
Guru
 
Jeff F's Avatar
 
City: Great Lakes
Country: Canada
Vessel Name: Mazurka
Vessel Model: Mainship 34 Original
Join Date: Nov 2015
Posts: 595
Quote:
Originally Posted by Island15 View Post
So if I take the return line off the top of the tank where it currently returns and just "T" it into the supply line before the fuel pump will that cause any problems?
I wouldn't. You risk drawing from the return port on the tank, and typically they don't have a pickup tube. So if your supply side is restricted you'd draw air from the return side. Keep them separate.
Jeff F is online now   Reply With Quote
Old 05-31-2017, 02:18 PM   #20
Guru
 
AusCan's Avatar
 
City: Adelaide
Country: Australia
Vessel Name: Kokanee
Vessel Model: Cuddles 30 Pilot House Motor Sailer
Join Date: Jul 2012
Posts: 2,870
I have a different theory.

The listing issue may not be only due to fuel tank levels. It may also be due to water tank or other storage issues.

When you equalize your tanks, the fuel flows from the high side to the low side, even if the low side has more fuel in it (and is overflowing).
__________________

AusCan is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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





All times are GMT -5. The time now is 12:23 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×