Engine runs 10 minutes then stops

[hugosalt]

Was bothering me...nylon washer... seems that somewhere along the way Yanmar changed from copper to nylon, at least on some filters.
However either could be cause for air leak, worthwhile checking.
And if you know size replacing, can source from local hardware/Grainger etc.

[s/v Jedi]

Ah, copper crush washers. Here is a way to re-use them successfully: heat them to bright red over a flame, then throw it in cold water. Now the copper is soft again and will seal the connection
(Annealing)

[skipperpete]

Hi eje, I had a problem with a 3GM 30 that just stopped and part of the troubleshooting revealed almost zero fuel pressure at the bleed screw and it was caused by a stuck pressure maintaining valve that was dumping almost all the fuel into the return line. I didn’t have time to fix the valve at the time so I just put a clamp on the return line and continued looking for what it was that stopped the engine. Not many 3GM’s have this valve but if your engine has one it could be part of the fuel starvation issue.
I’m a bit puzzled by the fact that you’re able to bleed the fuel system after refilling the little filter, do you get a good jet of fuel out of the bleed screw on the injector pump?
If you have a look in the “engines and propulsion” topic thread you’ll see my 3GM 30 thread with a photo of that valve and you can see how it functions.
I have to admit that I thought your fuel problem was a stuck valve in the lift pump but if you can get bleed pressure at the injector pump, that’s now unlikely to be a useful suggestion.
Following with interest.

[eje]

Originally Posted by hugosalt

Eje, don't remember a "nylon"
gasket on the bleed screw that you refer to in post #9.
I do believe that there are or should be what I call "copper crush washers" in several spots and they should be considered consumables. Thinking ?? that your nylon gasket
may be in place of a copper crush washer.

In any case changing out any of these copper washers on your filter will be cheap and easy next step in troubleshooting problem.
Hope this helps.

The nylon washer gasket 'washer' is item # 8 on the parts diagram, figure 46. I understand these are problematic. I agree on the other copper washers. I did buy some, but not enough to replace all on the fittings I'd loosened.

The clear hose would be a good idea, but the only section it would be easy to use it on is between the Raycor & the lift pump. Downstream of that it is either braided hose or hard lines.

[Cpt Mark]

I have 2 of those engines too and had the same problem. Eventually I replaced the electric priming pump and it started working fine. My diesel engine instructor told me the electric pump had nothing to do with it and the likely cause was a weak engine fuel pump. Bought one and have yet to replace it years after this nightmare. It was an air leak somewhere, very tiny that after disassembling, reassembling I magically got it right. My racor was the one that ran dry.

I believe you have an air leak. It could be in the braided hose but more likely their connection points.


Good luck.

[eje]

The only thing I see that looks like it could be a retun line is a rubber hose coming off the #3 injector.

[bil56]

on the Yanmar filter holder, there really is a plastic sleeve on top,
often the bleed screw is too tight and the thread is damaged, resulting in a low air intake but imminent failure ...

[skipperpete]

Originally Posted by eje

The only thing I see that looks like it could be a retun line is a rubber hose coming off the #3 injector.

Here’s the valve. The steel pipe from the injector pump is the return line and at the back of the engine it tee’s into the injector leakoff line and returns to tank[ATTACH]
Yanmar originally used “dowty washers” on fuel system banjo bolt connections.

[eje]

Originally Posted by skipperpete

Here’s the valve. The steel pipe from the injector pump is the return line and at the back of the engine it tee’s into the injector leakoff line and returns to tank[ATTACH]
Yanmar originally used “dowty washers” on fuel system banjo bolt connections.

Mine looks a little different. I don't see what I think would be the valve.

Frustrating week- But I do have it running.
I thought I had isolated and ruled out the Racor filter. Apparently not.
I put a line into a plastic can to the uplift pump, again, this time it ran for about 25 min until I shut it off. I bypassed the Racor filter and it ran until I shut it off.

Next week I can pull the Racor filter. I've also ordered enough brass sealing washers to replace all .

[Bill O]

Good to go back and recheck things.

What Racor model do you have?

[s/v Jedi]

Originally Posted by eje

Mine looks a little different. I don't see what I think would be the valve.

Frustrating week- But I do have it running.
I thought I had isolated and ruled out the Racor filter. Apparently not.
I put a line into a plastic can to the uplift pump, again, this time it ran for about 25 min until I shut it off. I bypassed the Racor filter and it ran until I shut it off.

Next week I can pull the Racor filter. I've also ordered enough brass sealing washers to replace all .

It’s almost always the primary filter. Look at installing a little piston fuel pump that I mentioned before: it not only shows where the leak is immediately, it also allows you to run the motor normally even with that leak and it makes bleeding the fuel system as simple as can be.


Annealing the copper washers is easy and they will perform as good as new ones. Even new ones work better when you anneal them (it was what finally stopped a leak I helped someone with once).

[Cpt Mark]

Originally Posted by s/v Jedi

It’s almost always the primary filter. Look at installing a little piston fuel pump that I mentioned before: it not only shows where the leak is immediately, it also allows you to run the motor normally even with that leak and it makes bleeding the fuel system as simple as can be.


Annealing the copper washers is easy and they will perform as good as new ones. Even new ones work better when you anneal them (it was what finally stopped a leak I helped someone with once).

Typically the electric fuel pump is for priming the engine only. It does not run when the engine is running. Mine is tied into the key switch and then has a manual switch in the engine room in a very inconvenient location that you have to hold down to engage. Let go and it springs into off position. I'm bypassing the entire key switch nonsense and installing a new switch next to the engine where I'm bleeding the injector pump from. Switch has a cover so when not in use can't be accidentally flipped on

[Cheechako]

Check your tank vent outlets. Bugs build nests inside the fitting on the hull. When it's blocked a vacuum is created when you run the engine.
Next time it stops try undoing the fill cap on deck and see if there is a rush of air in.

[MicHughV]

I had a situation similar to this once...a boat in the anchorage was having this problem, so I offered to help. We checked, cleaned everything, but the problem persisted.

Despondent that I could offer no help, I climbed back into my dink to head back to my boat, when I noticed the tank fuel vent was right in front of my face and it looked plugged up.

Turns out that the culprit was some mud dobber wasps that had been trying to build a nest in, on and around the tank fill vent on the outside of the hull.

The blocked vent causes a suction type affect inside the tank, preventing the fuel pump from drawing fuel.

Once this blockage was cleared, so did the fuel starvation problem and engine ran fine.

On a secondary note, I removed an old diesel fuel tank from my first boat once, and on a whim decided to open the inspection hatches. I was surprised to see the bottom and lower sides covered in about 1/4" of dark green slime. I was fortunate that the pick up tube had it's bottom about 1" off the tank floor, as any lower it may have started to suck up some of this junk.
If all else fails, one might want to consider having the diesel fuel go thru' a polishing process.

[s/v Jedi]

Originally Posted by Cpt Mark

Typically the electric fuel pump is for priming the engine only. It does not run when the engine is running. Mine is tied into the key switch and then has a manual switch in the engine room in a very inconvenient location that you have to hold down to engage. Let go and it springs into off position. I'm bypassing the entire key switch nonsense and installing a new switch next to the engine where I'm bleeding the injector pump from. Switch has a cover so when not in use can't be accidentally flipped on

When you get a specialized pump, you can run the fuel system in pressurized mode. 7psi is the most often used pressure. Check your Racor manual and you will see this is supported.

This pump doesn’t run when everything is fine, but you can run it when your filters are dirty, when you have a vacuum leak etc. and the engine will keep running instead of quitting. This may save your day.

For maintenance, it is used for bleeding and for finding those vacuum leaks, because now they become pressurized instead of vacuum, so diesel fuel sweats out of the leak (visible) instead of air in (invisible). It is the bees knees and I think dozens or even hundreds of boats have used my diagram to upgrade their system.