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Current Replies for Newbe with Yanmar fuel line problem looking for Yanmar Guru
 
  Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 8:47:33 pm on 8/8/2012 Modified: Never
 
Hello all

My Mark V with the 1GM10 has fuel problems and will stop running
by fading down in RPM when run up to 3000 RPM after it's been on
for at least 15 mins.  

If I prime the line from the engine's "lift pump" in line before the on board filter, I find some bubbles that would indicate air in the fuel line.  I can clear it buy using the lift pump but think the line coming from the fuel tank may be the problem.  (aft from the tank to the engine is not gravity fed and relies on the engine's "lift pump" to keep the fuel coming from the tank and hold fuel in the line between the tank and engine via an external filter assembly)  

I'm thinking that the line from the tank isn't staying primed but I can't tell.  If I prime the lines on the engine it runs but fades and never reaches full RPM except just after I prime all the lines.  

I've checked the engine for weeping fuel at all banjo connectors and bleeders are without any signs.  The filter can located after the lift pump was a problem due to being over tightened and did leak before I replaced it.  

Question:  How do you check the section of  fuel line coming from the tank?   That's to say, being primed and staying primed?  

Thanks  

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 9:50:20 pm on 8/9/2012 Modified: Never
 
Do you have a check valve in the system? Since you have a gradual deteriation in preformance of your diesel, I would give your tank a proper dosage of "Seafoam" to start cleaning out the sludge, all the way along the system. Sold at most autoparts stores.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 10:51:26 pm on 8/9/2012 Modified: Never
 
Scott

Thanks

I'll try that.  I see no sign of a check valve.  Is it
possible to be inside before the line exits the tank?  I
assume that if I have a perfect line without any possibility
of air infiltration, a check valve isn't needed?

Today I bought a hand pump and fitted it
with 1/4" fuel line nipples so I could try getting
a solid fill of fuel in the line from the tank
to the filter.  I pumped it into a container
and found no signs of sludge but there was lots of air
through out the pumping process before I got a solid flow
going.  Tomorrow I was going to see if the line, which I put back
into the filter and ran the engine up to full throttle (3500 rpm) under full load for about 20 mins, is still free of air.  I will
also pick up the Sea Foam on the way to the boat.  

I'll publish the outcome on the forum.

Regards

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 8:29:24 pm on 8/10/2012 Modified: Never
 
Check valves would be close to the engine but are not necessary. Any air in the line that you had, will not return. It may have got there by having a low level of fuel, and the line sucked in some air when the engine was running in rough seas. Possibly changing a fuel filter let some in. But it won't return.
You have sludge. Just just open up any old home heating system tank. The bottom is thick sludge. By the way, Seafoam is excellent in the crankcase as well.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 7:09:01 pm on 8/10/2012 Modified: Never
 
Today I went back and checked the engine and discovered more of the same problem.  The engine starts but will not sustain 2500 to 3000
rpm for more than 10 or 15 mins before it declines and stops.  I found that it was running off the fuel in the engine's filter plus external filter.  It seems to stop when the long fuel line running from the external filter to the tank had refilled with air and lost prime.  It will not re-prime off the lift pump.  There are no signs of leaks in the fuel lines.  I'm beginning to think there might be something about the tank internal fuel pipe which reaches down to near the bottom.  The anchorage is a little rough which would cause the fuel to slop around inside but it's 3/4 full.  Being that full, I wonder how air can get into the internal pipe inside the tank?  

When I replaced the fuel level sensor I put a tape measure inside to find out how much fuel was there.  In doing so, the tape measure came up from the bottom clean without any sludge.

Using a hand pump attached to the fuel line at the engine, I can prime the line and it will run fine afterwards but the following day I start to see these problems with fading engine and stopping. There is no check valve in the line.  I did add Sea Foam today.  The sage continues

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 9:08:43 pm on 8/10/2012 Modified: Never
 
More air prior to the lift pump. The line that descends into the tank probably is intact. The fittings at the top of the tank are a source of air if not snug. But I'm thinking the pump may be creating a vacuum in the tank, if the vent is blocked. And that vacuum will try to pull the fuel back into the tank. Churning it with air. The vacuum could draw air through the somewhat tightened fittings as well.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 8:40:17 pm on 8/11/2012 Modified: Never
 
Thank you for the new suggestion.  Im going through the fuel gantlet with this boat.  

I started with air getting into the filter due to the canister being over tightened thus the filter retaining ring required vice grips to get it open.  There was air coming from the bleeders all the time and weeping fuel from the o-ring joint at the bottom of the filter cup.  New gaskets and an o-ring weren't enough to fix it. I ended by replacing the filter assembly and put new gaskets.  The new filter can be hand tightened with a solid stop when it's tight. Also the fuel line between the filter and the lift pump was replaced.

Now the engine runs well at under 2000 rpm on the day I prime the line between the tank and the first filter.  The second day there is air in the line causing failure shortly after placing the engine under load. In all cases, I can't get it to run at 3000 rpm without fading down in RPM.  Air is getting to the injector!

I will explore the tank's fuel line fittings again and make sure there air leaks and there isn't blockage in the breather line going to the stern.  I am also checking the external cartridge filter to make sure it is the correct specification.  Ive heard that there are is a possibility of a filter with too fine a spec that will create a vacuum condition in the fuel line with it run under higher rpm.  

The saga continues

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 10:27:06 pm on 8/11/2012 Modified: Never
 
Scott

Today I spent another four hours on the engine fade out problem.  It's still doing it after I replaced the fuel line today.  The air intake line is free of any blockage.  The Sea Foam only makes the engine purred more smoothly but it stopped both times after running about 20 minutes, once at 2500 rpm and the other time at 2000 rpm.  It just plain slows down and stops within a minute of first sounding of an RPM decrease.

I took great pain to prime the fuel line going to the external filter, the filter, the line from the filter to the fuel feed pump, fuel strainer and bled the air out of the fuel injection pump.  Both times the engine started right up and ran smoothly all the way up to 3500 rpm under load.  I also checked the new fuel line by siphoning it into a gallon container and the flow appears normal for the height of fall.  I drew a quart each time to make sure there was good flow.  The fuel is clean but a little darker than new fuel.  The amount of sludge that appears on the bottom is minimal.  

With both attempts the engine ran beautifully before fading and stopping in under a minute. The first time I took a look in the large bleed screw on the fuel strainer and found it to be dry and I could add about a full canister amount to fill it.  The fuel line before that point were dry with the external filter having a reduced amount of fuel.  It clearly showed me that both times the engine became fuel starved and shut down.  The new fuel lime lost it's prime.  

I am dumbfounded!  Any new ideas will be greatly appreciated.

Thanks

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (oasis)
Posted: 11:40:13 am on 8/12/2012 Modified: Never
 
Since you appear to have good fuel flow, maybe the fuel pump is the problem?

Just a guess, I am not a mechanic by any stretch.

Barry  Oasis, 1987 Mk V
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 2:03:03 pm on 8/12/2012 Modified: 2:28:15 pm on 8/12/2012
 
Where is the new fuel line? Is the from the lift pump to bottom of the tank? I have your operating manual at www.marathondiesel.com. Page 29 for diagram. Have you drained a bit from the tank?
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 9:53:33 pm on 8/12/2012 Modified: Never
 
The fuel lines I've replaced are all the low pressure sections between the fuel tank, exterior filter and lift pump.  That is
two sections.  I have an external filter near the engine.  Eaton RACOR 12SUL rated at 15 gal/hr.and I changed the cartridge recently. It is followed by a short section of hose that connects to the lift pump input which is the second piece of hose I replaced.  

Today I attended the Rockland Boat Show and received some suggestions from a Yanmar dealer.  He says they see tanks that have leaks in the lift tube inside the tank thus loosing siphon if they are old and corroded.  To test for that possibility the plan is to use another tank of fuel by placing a hose into this external fuel tank, make sure it's primed and go through the same under load tests.  If the problem goes away I'll know that the problem is most likely inside the tank.  If it still occurs, then it would indicate a problem with the lift pump.  

I hope to get time to go the next step tomorrow.

Page 29? what it the info there that you are aiming at?
 

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 7:43:50 pm on 8/13/2012 Modified: Never
 
From page 29, it shows that the line in the tank is comletely submerged. So any pinholes in it are without consequence. I assume you do not have the optional #6 drain cock. In Figure 1,1 there is a vent line from top of the tank to the bottom of the tank. How it works, I'm not sure!
If you have to switch out the lift pump, there are some cheap universal pumps available with the same fittings.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 9:44:40 pm on 8/13/2012 Modified: Never
 
Scott

Thanks for clarification.  I reviewed the diagram you on page 29.  The tank I have is a standard C&C tank that was used in all the boats made in Rhode Island in 1986.  All 4 ports, fuel input, vent, fuel to engine and fuel return are on the top.  Therefore, this doesn't conform with the diagram on page 29.  I too do not understand that pictorial of the line showing it exiting and returning to the tank near the top and bottom.  I don't think it applies in my situation.

My experiment with the temporary fuel tank will also include placing
the tank at the correct elevation with the column of fuel in the line going up in height above both the engine and tank. It must remain primed during all conditions of operation and non operation to prevent engine failure.  The model for this boat requires I simulate fuel rising above in between the tank and engine without loosing prime.  If my test allows the engine to operate without fading I will leave the temporary tank configuration over night to see if any slow air leak causes loss of siphon.  

We'll see!
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 2:43:14 pm on 8/13/2012 Modified: Never
 
Another test to do that is quick. Disconnect the lift pump of power. Usually dormant pumps let fuel through. Some of these C&C 27s run with only one 2-4 psi pump for the Atomic 4.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 7:54:42 pm on 8/13/2012 Modified: Never
 
Scott

Unlike the Atomic 4, the Yanmar has a lift pump that runs off a mechanical arm connected to the engine and it has a little external arm for priming by pumping it manually with a finger or two.  I don't know how to disable it.

Today I made progress.  The tank is now out of question!  That's a good thing because it would end our season early.  There isn't any way to get it out of the boat without taking the engine out so it can be slid forward into the cabin and out through the companion way.  

Why is the fuel tank out of question?  Because I got the same fading and stopping in identical circumstances with the external tank testing connected to the external RACOR filter/H2O Separator unit.  I also observed the strainer/filter on the engine was pumped almost dry as well.  I then bypassed the RACOR by connecting the fuel line to the lift pump and the problem didn't reoccur during my testing.  The engine continued to run normally with peak RPMs around 3600 under load.  

I am now replacing the RACOR 120RAMA assembly.  It's 30 microns and rated at 15 gal/hr.  It will be towards the end of the week before I can take on this last step.  In the meantime I will start the engine and reconfirm that the siphon isn't lost with air after the engine cooled.  The filter connections show signs of stress from being over tightened which resulted in a minor air leak, just enough to cause the engine to loose the fuel in the line coming from the tank. Thus the engine runs out fuel when the strainer filter was sucked dry by the injector pump.  

Lets hope time will prove this out completely once I replace the filter/separator between the tank and lift pump on the engine.

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (sony2000)
Posted: 10:37:00 am on 8/14/2012 Modified: Never
 
There is a clue in that the previous owner had overtightened the filter with cause. But maybe he had chosen the wrong one, as being problematic.
  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (Hardlee)
Posted: 10:26:50 pm on 8/16/2012 Modified: Never
 
Scott

I went to the boat after it sat for two
days and it started right up and ran perfectly.

Therefore no new air had sucked in as it did
previously with the RACOR filter in the line.

It's also interesting to note the Mack Boring
has a replacement version in stock that the will
sell directly to end users.  It's a non-Yanmar 3 party
part which allows them to do so. P/N 4120 It has a reduced
number of ports which reduces possible air leaks.  

The Yanmar engine should not be run without this filter fuel/h2o
separator except as I did to trouble shoot the possible problem.

I put the new unit in place tomorrow

Thank you for helping me work through this problem.  

John Lawrence
Northern Dancer, Mark V, 1986
Muscongus Cove, Maine

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (colinambler)
Posted: 8:18:04 pm on 9/4/2012 Modified: Never
 
Hey John,

This is great thread!  You've done your homework and more than fair share of troubleshooting.  From one "newbie" to another---I'm impressed with the effort and extensive steps taken (for what that's worth).

I'm also an owner of a 86' Mark V and check this forum periodically for posts that might be relevant.  A few weeks ago I skimmed this one as it sparked my interest.   Low and behold, this proved to be foreshadowing because now consequently, I'm experiencing the exact same issue with my engine!  Ugh. Unexpected power decreasing after approx 10 ish minutes and then full stoppage.  

Bleeding the air from the fuel lines seems to get her started again, but the last 3-5 attempts have resulted in the same failure.  Similar symptoms also include difficulty reaching higher RPM's, as you mentioned.

So, with what seems your troubleshooting coming to an end...mine begins.  I'm hoping I can learn from your experience!

I'm a little confused by your last post.  If I understand correctly, RACOR is a manufacturer of filters and you [almost certainly] determined the installed part to be faulty through your most recent test.  So, a replacement of the fuel filter/h2o separator should do the trick?

Any info and advice would be appreciated from your experience!

Thanks in advance,

Colin Ambler
C&C 27 Mark V
Chicago, Illinois

  Re: Newbe with Yanmar fuel line problem looking for Yanmar Guru (oasis)
Posted: 5:36:36 pm on 9/5/2012 Modified: Never
 
Or maybe just fuel filters need to be replaced?  Earlier this summer mine had similar "performance", which started very suddenly.  Had spare primary and engine filters on board (because I knew it had been a few years since they were replaced).  Replaced them both.  Problem gone.

Barry  Oasis, 1987 Mk V