Yanmar diesel shutting off

[casual]

I,just finished a 6 mo refit on the hard.I,have 2 fuel tank's the lower tank has no problem.I,can get fuel to the Racor filter from the top tank and the engine start's run's for 5 to 6 minutes shut's down.Let it sit for a minute of so the engine restarts but will only run for 1or 2 minutes.I,replaced all fuel lines both Racor filters to eliminate air leaks.No problem when using lower tank same problem with upper tank.Could I,have grunge clogging the filter after 10 or so minutes of running then settleing and then letting the engine run again.If that is the case will recirculating the fuel thru a seperate filter back to the tank do any good?Should I,pump the tank out and remove for cleaning.
Thank's all any and all ideas will be welcome

[xymotic]

you need three things to run the engine.

Fuel, Air, compression.

Does the motor behave any differently if you rev it higher?
You could have a fuel pump issue, something with the injectors, maybe a blocked return line. You just have to tackle them one by one and see what's happening.

But to answer your question, yes crap can easily clog a filter very rapidly. And it might fall away when the suction goes away. The easy way to test is to simple get fuel straight from a can. If that works you have to do 'something' with the fuel in the tank, either clean it or discard it.

[bob_77903]

You probably have a sock like screen filter on the end of the tank pickup tube. Check to make sure it's not caked with crud and clogged. I had the same symptoms your describing on my Yanmar, and that's what it was.

[Aloha_float]

How old is the fuel? It is possible the strainer is plugged. I had my engine shut down due to sludge plugging a 2 micron filter in my fg500 unit. I replaced the filter with 10 micron and treated with fuel right sludge dissolving additive. It worked and my engine has been running great all season.

[casual]

Originally Posted by Aloha_float

How old is the fuel? It is possible the strainer is plugged. I had my engine shut down due to sludge plugging a 2 micron filter in my fg500 unit. I replaced the filter with 10 micron and treated with fuel right sludge dissolving additive. It worked and my engine has been running great all season.

Thank's guy's The pick up tube is located top of tank.Tank is directly under cockpit tank is appx 14"deep distance between tank top and cockpit under is appx 4".That was my thought but no can do.That's whyI,thought about putting a long line on the pick up side put an electric pump in line and filter the fuel out and back to tank or empty and remove tank.I,put algeside in when I,went on the hard and filled both tank's hoping this would not happen.This fuel right dissolving might be worth a try where is it available?
Thank's again

[casual]

Originally Posted by xymotic

you need three things to run the engine.

Fuel, Air, compression.

Does the motor behave any differently if you rev it higher?
You could have a fuel pump issue, something with the injectors, maybe a blocked return line. You just have to tackle them one by one and see what's happening.

But to answer your question, yes crap can easily clog a filter very rapidly. And it might fall away when the suction goes away. The easy way to test is to simple get fuel straight from a can. If that works you have to do 'something' with the fuel in the tank, either clean it or discard it.

Good idea but running off the bottom tanks all is well brought the boat home fom yard 12 miles even red lined it for a mile.Each tank has a seperate filter with lines going to selector valve.

[gjordan]

Try disconnecting the outlet side of the selector valve and see how much fuel flows from the top tank. If the lower tank is also gravity fed to the valve, compare the flow, if not, just see if the flow from the top seems good enough? It could be a restriction in the valve itself. You might have to start a siphon with one of those cheep brake bleeding pumps you can buy at Napa Auto._____Good Luck_____Grant.

[casual]

Originally Posted by gjordan

Try disconnecting the outlet side of the selector valve and see how much fuel flows from the top tank. If the lower tank is also gravity fed to the valve, compare the flow, if not, just see if the flow from the top seems good enough? It could be a restriction in the valve itself. You might have to start a siphon with one of those cheep brake bleeding pumps you can buy at Napa Auto._____Good Luck_____Grant.

Thanks the bottom tank is below and fuel is lifted,had another idea see what u think.Disconect line from top tank filter reconnect to bottom tank filter after disconnecting line from bottom tank.If history repeats itself has to be in the top tank if not I,have a bad filter filter housing or valve,Sound resonable?

[decktapper]

Another possibility is a clogged vent line. Once you pull a vacuum on the tank you can't get more fuel out. Try removing the fuel cap and see if that fixes the problem, if not, thats not the problem

[Pallykin]

Yet another possibility is that you have a leak, and your fuel line is sucking air instead of fuel...

[Aussiesuede]

Originally Posted by decktapper

Another possibility is a clogged vent line. Once you pull a vacuum on the tank you can't get more fuel out. Try removing the fuel cap and see if that fixes the problem, if not, thats not the problem

Yep, his syptoms are EXACTLY that of a clogged vent.

[Kelpie.Ohlson38]

Hi there,

We had the same problem with our yanmar. We added a small 12v electric fuel pump and it fixed the problem. We must have had a small air bubble somewhere, but we just couldn't seem to bleed it out. Good Luck

[donradcliffe]

If you an't access the pickup tube on the top tank, disconnect the fuel line and blow some compressed air back through the pickup tube--it will knock any crud off the pickup strainer.

[Amnesia II]

Exact issue happened to me in French Poly. Could not find the problem after checking tank, pickup pipe, lines and Racor filter.
Engine would run then die after 10 mins. Finally pulled off the Yanmar fuel filter on the motor and it was full of sludge.....changed the filter and bingo!

[noelex 77]

As the engine runs fine from the lower tank you have at least narrowed it down to where there can only be a few possible faults.

The one that has been mentioned by Aussiesude would get my vote as the most likely. A plugged vent line to the upper tank. This will cause the engine to run fine until the vacuum formed prevents the engine sucking up diesel often around the 5-10 min mark just as you describe.

The good news is that it should be an easy problem to diagnose and fix. If you can loosen an inspection hatch, sender or even the fuel return line to let in some air to the top of the tank the engine should run normally if the vent is the problem.