Yanmar 4JH5E stalls when starting

[Sailing Drummer]

Today was basically the same, except this time I left the throttle in the normal position instead of pushing the revs up. Same results. Twice actually - once before we weighed anchor and then about 2 hours later leaving the fuel dock. Hopefully tomorrow I can get to the engine and bleed it and see what happens. At the very least I'll be able to see if the electric pump is working. Actually, I'm hoping it is the pump. That's something I can fix by replacing it!

Larry

[sck5]

What bean counter said. And extra fuel line isnt a bad thing to have around

[Sailing Drummer]

So, I bled it this morning. The pump is working. It took about a minute to get the fuel coming out - way too long. After that (I should have checked first) I checked the Racor and it was totally full. The motor starter up the way it's supposed to start. First try @ 1000 rpm and continued running. So there's obviously (to my way of thinking) air in the system. Possibly from the last filter change? Tonight I'll see if it starts up normally after sitting all day not running. I'm hoping it was simply some old air trapped in the fuel line and then made its way to the fuel filter - but I know I can't be that lucky! So, it appears to be loss of prime, but don't know the reason.

I'll post again after I try to start tonight. Thanks for all the suggestions. I'm learning a little bit about diesels thanks to CF!

[Sailing Drummer]

Same problem this evening. I've got to trace this from the tank to the filter. For now I'll have to live with letting the pump run longer before starting - no a fix but a workaround until I find/fix the issue.

My plan is to first carefully inspect the hoses at each fitting. If that doesn't result in anything I'll move on to replacing hose.

I'll start with the highest hose and then work my way down until I find fuel. To my way of thinking, the air leak must be higher than where I find fuel. Does that make sense?

Larry

[a64pilot]

I’d try pressuring the system with an electric pump and letting it sit pressurized, May take awhile, like an hour or so.
You may find an air leak by looking for a fuel drop.
Very unlikely to be the hose. Much more likely to be a connection.
On my Duramax it was simply the bleed screw was loose, felt like a fool when I found it, but glad it was simple.

[Sailing Drummer]

a64, I tried that today. Couldn't find anything. I'll be traveling for about 5 days starting Thursday so I'll check each day when I shut down the engine. So far I've been able to start each day. I'm hoping this continues to be the case so I can get back to the Chesapeake and if need be take it to a local mechanic at my home port.

For now I'll be priming using the electric pump for about 20-30 seconds. That should get her to keep running. But there is definitely a problem that needs to be found out and fixed. A connection being the issue makes sense. But if I can't find where air is getting in I can see a lot of fuel hose purchase in the future!

Larry

[NYSail]

Remember with the exhaust..... the clog might not be with the water side. My last yanmar had excellent water flow however upon inspection the exhaust side was about 75% clogged.
To test for loss in prime, closed fuel shut off immediately after use, then open right before you go to restart. Slowly go over all clamps and fittings and tighten. When you replaced racor I am sure you replaced all gaskets.... make sure the lid gasket isn’t twisted...
Good luck!

Greg

[Uncle Bob]

Originally Posted by Sailing Drummer

a64, I tried that today. Couldn't find anything. I'll be traveling for about 5 days starting Thursday so I'll check each day when I shut down the engine. So far I've been able to start each day. I'm hoping this continues to be the case so I can get back to the Chesapeake and if need be take it to a local mechanic at my home port.

For now I'll be priming using the electric pump for about 20-30 seconds. That should get her to keep running. But there is definitely a problem that needs to be found out and fixed. A connection being the issue makes sense. But if I can't find where air is getting in I can see a lot of fuel hose purchase in the future!

Larry

Have you revisited any work done just prior to the problem appearing? Were there any filters that may not have had a new seal installed, or a new seal that may not have been seated properly (don't ask ), a fitting that may have been "adjusted" etc, you get the picture.

[Sailing Drummer]

So.... this morning same issue. After shutting down I closed the fuel shut off immediately. This afternoon I started the engine having the same issues. But what does that tell me? That it's in the feed not in the return?

There wasn't anything done to the engine within about 100 hours of run time. That's when the Racor and the fuel filter were changed, and the engine has been running fine until this just started happening. However, when I checked the Racor today I noticed the square O-ring was not in the top. It was sitting on the edge of the body of the Racor. When I checked the other day I didn't notice if this was the case. I only checked to see if there was fuel all the way to the top. I missed looking at the O-ring. So I put the ring in the groove making sure it's not twisted and tightened it. I ran the engine long enough to get to operating temp and then shut it down. This evening I'll try the normal start procedure and see if this was the problem. Fingers crossed!

[NYSail]

The o-ring falling out when new is not uncommon... just make sure its not twisted and is coated with fuel. I have the 4JH4E and it has an engine driven fuel pump... off cam. There is in that a small screen filter that can also get blocked..... think you said you have an electric pump, however does that have an internal filter as well??

Good luck

Greg

[Sailing Drummer]

NYSail - to my knowledge there is no internal filter. I can not see any way it comes apart to get to one.

[NYSail]

I never checked on my new engine however my prior Yanmar you had to take the pump off the engine and disassemble the pump to get to the screen. Very user-friendly right ......

[Sailing Drummer]

The o-ring was not the problem! Still having the same thing happen. Traveling starting Thursday so won't be able to continue trouble shooting until we get to St Augustine.

[Sailing Drummer]

The last 2 days the motor started the way it's supposed to. No loss of prime. So maybe it was the o-ring on the Racor? I'll see how it goes tomorrow morning.

Larry

[01kiwijohn]

Originally Posted by Sailing Drummer

The last 2 days the motor started the way it's supposed to. No loss of prime. So maybe it was the o-ring on the Racor? I'll see how it goes tomorrow morning.

Larry

Looks like you've got it. Good job Larry