Yanmar 3GM30F not starting after fuel filter change

[skunther]

The engine was due for a secondary fuel filter change (the primary Racor has 300 hours on it, specs call for change every 500 hours, so I didn't change that one). I changed the secondary, bled the valve at the filter til fuel ran clear (though the lift pump works very slowly - any way to know what position to put the crank at in order to get more out of the lift pump?), then continued pumping as I tried to bleed the injector pump. It did bleed a bit of diesel on a paper towel I put under the bleed screw, and after about 5 minutes of pumping, it seemed no air was coming out, only fuel, however so little came out that it was very difficult to discern if I had actually bled the injector pump or not. I then undid the feeder lines at the injectors, flipped the decompression valves and shut the water intake seacock, and turned the engine over, going back and forth between the starter switch and engine (starting for 15 seconds, then looking at the engine, then back to the starter) until I saw fuel on the paper towels I put under the feeder lines at the injectors. #1 and #2 showed fuel, though #3 never did, in spite of 7 or so cranks of 10-15 seconds. I finally reconnected the lines to the injectors, closed the decompression valves and opened the seacock to try turning it over as I had learned these engines are meant to be self priming from the IP on (is this correct?). Now, after multiple attempts, I am getting very weak sputtering of the engine, but no actual firing.

I am concerned I may be causing problems by cranking without starting (water coming back into the engine?). What should I do at this point? Changing the filter seems should be a simple job, but somehow I have a way of complicating it.

I'm not sure what to make out of fuel not coming out of feeder line #3.

The engine did run well enough before the filter change, though somewhat rough.

 

[Tally Ho]

I would re-bleed the system, and pay particular attention to cylinder #3. Once you are sure you have the lines bled, you can close the cooling water intake valve, and try to start the engine (no cooling water pumping). If it starts, shut it down and open the thru hull and then restart the engine. If you are worried about your impeller, you can remove it.

As you already know, you want to be careful about hydro lock…

I assume the decompression levers are closed?
String battery and engine turning over pretty quickly?
Fuel cut-off in the run position?
Fuel valve open?

I have a 2GM20F and it doesn’t seem too sensitive to a little air (I changed my filters and didn’t even bleed the system. Just started it up and ran it at the dock with a load on it for 10 minutes.

I hope you solve it.

Greg

 

[Ralph Johnstone]

Changing the filter seems should be a simple job, but somehow I have a way of complicating it.

You can avoid the fun and games of air in the fuel ling by ensuring you vent all of the air out of the air vent on the filter housing. First the secondary first and then the primary. Pretty sure your primary looks like this :

Make sure you vent vents this filter a couple of times to make sure there's no air left in the line. A further help is to insert a shut off valve right before the secondary filter so you can control the venting.

Also make sure you have good hydrostatic pressure in the fuel line before the secondary filter to properly purge the air from the rest of the system.

 

[NYSail]

When changing the on engine filter (secondary) always fill the bowl before you screw back on. Assume you changed the o rings as well. When bleeding the secondary filter, open the bleed screw and make sure when pumping that you do a complete stroke down…… that little extra is where you push the fuel. At that point I would try and start the engine and not worry about the injectors….. but now that you cracked the injectors you need to bleed each one till fuel comes out. Good luck.

 

[Scott T-Bird]

I had a mechanic on board when I launched yesterday since I had to bleed the air after an initial start. He was right there while we launched the boat, so he bled the lines while I started the engine. In the end, after just a short period of bleeding, I had a pretty big mess of fuel to clean up. I don't know if he over-did it or not, but there was a lot of fuel bled. Your description seems to be telling me that you are not getting fuel flow for some reason. Perhaps you are not bleeding all the air, or perhaps there is an obstruction in the fuel flow. I had enough fuel escape that several wads of paper towels were needed to clean up the mess. But I did have my 3GM30F running, which always makes me happy on launch day!

 

[skunther]

Thanks for the responses. I did not fill the bowl, tho I was able to purge the air with the lift pump and bleed screw. Ultimately I was able to start the engine by having my wife turn it over for while the decompression valves open for about 7 seconds before I closed them all at once. The engine fired right up, and all three cylinders are firing.
Next time I won’t pull the fuel lines at the injectors.

 

[NYSail]

Thanks for the responses. I did not fill the bowl, tho I was able to purge the air with the lift pump and bleed screw. Ultimately I was able to start the engine by having my wife turn it over for while the decompression valves open for about 7 seconds before I closed them all at once. The engine fired right up, and all three cylinders are firing.
Next time I won’t pull the fuel lines at the injectors.

And fill the bowl……

 

[sailcapt340]

On my 340, same engine as you, isn’t there a bleed screw on the Racor filter top housing.
I fill the bottom part with clean fuel using a small measuring cup, screw it back onto the top housing. Minimal fuel dripping, not completely clean but minimal.
Open the shut off on the tank. Then have my wife hold the shut off at the helm while cranking the engine. This whole process takes about 15 seconds and there is fuel coming out of the bleed screw.
Then I tighten the screw and go to the little fuel pump handle on the side of the engine. Open the bleed screw on that and pump the handle until fuel comes out and there’s is noticeable resistance on the handle.
Thats it. Done.
Then I start the engine, it may run slightly rough in the first few seconds but smooths right out.
Once you have a system for yourself it will be a very smooth process going forward from here on in.
I have never open the injectors as you described in 23 years. But I also only have 411 hours on my engine, so there really is no need for what you described for myself.
Your system is closed and clean now, with all new filters. Going forward you should have no trouble or that level of work again.