Engine runs today--dies tomorrow

[sidsail]

I am having problems with my westerbeke century 120 hp.. After bleeding the fuel system. The engine runs fine for hours but the next day it will only run for 5 minutes or so .Emptying the racor.. Prime it again, runs for hours and then the next day the same thing.. I have replaced all filters, checked for blocked fuel tank vent, loose fittings on all hoses, switched fuel tanks, checked o-rings on racor, swithced to other filter on dual racor and the same happens everytime.. I cannot think of anything else to try.. Help

[Target9000]

How are the fuel tanks connected? If you switched fuel tanks and filters and the problem is still going on... I'd start at the engine and work my way to the first selector which I'm assuming would be the racors.

Look around all the connections closely. Black hoses make it hard to see splits and pin holes. Has a hose clamp cut one of the hoses? etc.

Air leaks can really suck to hunt down. =(

[sailorchic34]

Oh joy an air leak. Lucky you.. Though as it runs 5 minutes, its a leak upstream of the racors. That is, its draining the racor, but not sucking new fuel from the tank. Maybe a bad hose??? or a cracked pick up tube.

Do you have a vacuum gauge on the racor's?? How do you reprime the racor's??? Inline pump???

[Boracay]

I had the opposite problem with our John Deere 4045D. Engine hard to start when hot but easy when cold.

Did the usual everything. Things getting worse.

As part of my ongoing upgrade program I had ordered a Walbro 22 electric fuel pump to replace the cheap POS that I put in a few years ago.

Kept putting off putting it in. Too many other things to do.

Finally in Brisbane bit the bullet, but first I took a look at how the old pump was going. Diesel was streaming out of it!

Spent 4 days ordering every special barb for the pump available in Brisbane (now have 4). Bolted in new pump. Engine now starts flawlessly

So what I'm getting at is there has to be an air leak between your fuel tank and your injector pump. Keep on replacing bits till it works. I was about to replace the fuel line.

I can recommend Walbro fuel pumps. Just make sure you get all necessary barbs and adapters when you order.

[John A]

If the engine races before quitting then, more than likely its an air leak.

You can isolate the air leak using a transperant tube (hose) and an outboard engine fuel bubble pump. Attach, with hose clamps, at the racor and pump fuel thru the line to check for air bubbles. Next check between the racor and the engine fuel filter, and so on down the line. Also check for any fuel leaking from anywhere - if fuel can leak out then air can leak. This inexpensive way of check the fuel systems is much easier than replaceing parts that don't need replacing.

If the system is not replacing the fuel in the racor you may need to clean the internals of the racor.

[sidsail]

How are the fuel tanks connected? If you switched fuel tanks and filters and the problem is still going on... I'd start at the engine and work my way to the first selector which I'm assuming would be the racors.

Look around all the connections closely. Black hoses make it hard to see splits and pin holes. Has a hose clamp cut one of the hoses? etc.

Air leaks can really suck to hunt down.

Thanks all for your suggestions. I will start again tomorrow finding the problem. The tanks are separated by two valves return and feed. The engine is a new install 2008 so the hoses, tanks, filters etc. are relatively new. There are no visible leaks in the hoses and i do not see cuts in the hoses. I have checked every hose clamp and see nothing amiss. If the problem is an air leak wouldn,t the fuel run back into the tank from the racor and not run longer than it takes to burn the fuel in the engine? It runs for five minutes or so... I added a link of the sailboat but not clever enough to do it properly.. Thanks
https://picasaweb.google.com/lh/phot...eat=directlink

[sidsail]

If the engine races before quitting then, more than likely its an air leak.

You can isolate the air leak using a transperant tube (hose) and an outboard engine fuel bubble pump. Attach, with hose clamps, at the racor and pump fuel thru the line to check for air bubbles. Next check between the racor and the engine fuel filter, and so on down the line. Also check for any fuel leaking from anywhere - if fuel can leak out then air can leak. This inexpensive way of check the fuel systems is much easier than replaceing parts that don't need replacing.

If the system is not replacing the fuel in the racor you may need to clean the internals of the racor

Thanks John, The engine does not race. More of a choking and rattling death..
Also, why would it run fine after bleeding and then die the next day..

[SkiprJohn]

I'm helping a friend locate an air leak in his system. We took the fuel line off the exit of his fuel filter and stuck it straight into a container of clean diesel. Now it runs just fine and starts right up. Now we know that the air leak is either at the fuel filter or the hose and connections to the tank. Next thing we'll do is the outboard engine bulb trick to see if we can locate any wet spots on the hose or in fittings from the tank through the fuel filter. All we need to do is put the bulb somewhere in the fuel line between tank and first filter then give the bulb a bunch of squeezes to put some pressue through the system.
Good luck on locating your air leak. Thw Walbro pump idea is a good one. Even with a small leak you'll still get fuel to your engine.
kind regards,

[Rocketman]

I had an engine that did the exact same thing yours is doing, I checked and double checked everything, no leaks anywhere, So I replaced the lift pump, still the same thing, then I ordered all new o rings seals that go in the conection fittings in the fuel lines and replaced all of them. This did it. I do not know which one it was but one of them leaked.

[SkiprJohn]

It could run fine because it is a very little leak that is barely noticeable while the engine is pumping fuel but when the engine shuts down and has 12 to 18 hours to sit there and let air into the system it'll just starve for fuel after 5 minutes of running. I've never had a diesel race before running out of fuel. My outboard does though.

regards,

[sailingwave]

Originally Posted by Target9000

How are the fuel tanks connected? If you switched fuel tanks and filters and the problem is still going on... I'd start at the engine and work my way to the first selector which I'm assuming would be the racors.

Look around all the connections closely. Black hoses make it hard to see splits and pin holes. Has a hose clamp cut one of the hoses? etc.

Air leaks can really suck to hunt down. =(

just change all the pipes (if you have spares?) trying to find a leak will take longer!

[sailorchic34]

Originally Posted by sidsail

Also, why would it run fine after bleeding and then die the next day..

You have a very small air leak. So small that the engine will run fine after priming, but waiting 12 hours or so and it drops the fuel before the racors back to the tank.

If the leak was after the racors and the racors were above the tank then the racors would also drain back to the tank. As the engine runs 5 minutes the next day, we can be pretty sure that the leak is before the racors.

If you had a really long run of fuel hose after the racors, it still could be the racors

I wonder if one of your tank selector valves has a leaky valve stem gasket, its not under pressure so would not show a leak

[Rakuflames]

Originally Posted by sidsail

If the engine races before quitting then, more than likely its an air leak.

You can isolate the air leak using a transperant tube (hose) and an outboard engine fuel bubble pump. Attach, with hose clamps, at the racor and pump fuel thru the line to check for air bubbles. Next check between the racor and the engine fuel filter, and so on down the line. Also check for any fuel leaking from anywhere - if fuel can leak out then air can leak. This inexpensive way of check the fuel systems is much easier than replaceing parts that don't need replacing.

If the system is not replacing the fuel in the racor you may need to clean the internals of the racor

Thanks John, The engine does not race. More of a choking and rattling death..
Also, why would it run fine after bleeding and then die the next day..

Any chance your fuel tank has accumulated dirt?

[sidsail]

I wonder if one of your tank selector valves has a leaky valve stem gasket, its not under pressure so would not show a leak.

I have tried both tanks and it dies the same..

[sidsail]

Thanks all. I did as suggested here and forced fuel through the lines and found one fitting loose.. I will fire it up in the morning and all should be well. Many thanks to you for taking time to help.. I,ll post back manana with a full report.. Thanks again.. sid