Couldn't start 3gm30 today

[Ereiss]

Had a leak in the secondary filter. Removed the bowl, put some teflon tape on the thread in hope of getting rid of the drip. Didn't really work as the teflon bunched up as I was threading the bowl back on. Bled the bowl and replaced the bleed screw and washer.

Tried to start the engine, ran for 30 seconds then died. Decided needed to bleed the injectors. Took my trusty 17mm wrench and cracked the three feeds but never saw any fuel come out despite repeated cranking. Retightened the fuel feeds and tried to start the engine. No go.

It would seem that fuel isn't getting that far. What could cause that? Could a bit of teflon tape blocked something? I would have thought if a piece got in there then the secondary filter would have caught it.

5 hours of effort, no success. Any hints would be appreciated.

[dwight]

Ed

When wrapping the Teflon tape, be sure to wrap in the same direction you tighten the fitting. This will prevent it bunching up.

Check that you are getting fuel through the mechanical pump by cracking the fitting on the inlet to the metering pump. If you don't get fuel there, the problem is in the supply system. If you do get fuel and still don't get fuel at the injectors the problem is the metering pump. Don't indiscriminately remove the metering pump. There are shims under the pump to compensate for manufacturing tolerances. The thickness of these shims determines the timing of the injection...very critical. They must be precisely measured and are unique for every engine.

If you are cranking for any period of time be sure to remove the muffler drain plug. This will prevent cooling water from filling the exhaust, backing up into the cylinders and causing more problems. When the engine starts some exhaust will come out of the drain hole but you can put the plug in while it is running.

[Ereiss]

Thank you Dwight.

So the teflon wasn't a completely crazy idea, just not well executed I guess.

When cranking I closed the water seacock so as not to pull water into the cylinder. Going to ask Bill at Bristol Marine to have a go at it. Almost lost it after spending 2 hours just trying to remove and replace the bleed screw. How do they manage to make things so completely inaccessible.

Hope you are well.

[GeoffSchultz]

Here's a reply that I received via e-mail from Alan Kusinitz. I guess that he thought that he was reading the yahoo group. I'll simply post it for him.

Years ago I had problems with air in the fuel system causing the engine to be hard starting and eventually die.

There are many points this can occur on my Yanmar 3GM including the copper washers used under the bleeder and at most of the fuel line connections. Yanmar indicates these should be replaced each time one loosens/removes what piece holds them down. Most mechanics don’t replace them and usually they hold up for a number of uses. Yanmar changed the material on some of them in recent years.

Any gasket or the plug in the bleeder itself could let air in.

Alan

[Ereiss]

Thank you all. The yard says it will be 3 weeks before they can help me. So on Friday I head down to try and trace cause of why no fuel is reaching the injectors. Plan to just follow the fuel from the secondary filter up to see where it stops coming out.

Two things;

1. Any suggestions, thoughts, cautions (Dwight, got yours on not removing the high pressure fuel pump)?
2. Any mechanic recommendations in the Bristol, RI area who can do a house call if I fail?

as always, thank you.

[GeoffSchultz]

Another reply via e-mail. This time from Fred Molden

I ran my 3gm30 out of fuel once and had to bleed to restart. I tried for an hour bleeding at the fuel bowl to no avail. Final solution was to bleed at the junction where the line from the fuel bowl goes into the injector pump.

Good luck

If bleeding does not work try

DePaul Service, Inc.
East Passage Yachting Center
9 Lagoon Road, Bldg. 124
Portsmouth, RI 02871
(401) 683-2330
Fax (401) 683-4858

[Ereiss]

thank you

[GeoffSchultz]

Ed,

Just remember that diesels are really simple machines. They need 2 things: fuel and compressed air. In this case you seem to have already determined that you're not getting fuel, so you simply need to trace the fuel.

1. Start with the Racor and work forward. Disconnect the hose from it and make sure that you're getting fuel flow.
2. Next, when was the last time that you replaced the Yanmar fuel filter? If it's been a while, perhaps now is a good time.
3. Then crack the bleed screw on the fuel filter and use the manual pump to make sure that there's no air in there and that fuel is flowing.
4. Pull the high pressure fuel line off of an injector and turn the engine over to see if you're getting fuel there.
5. Pull the injector and check to see if you're getting spray. At this point I'd bet that you are, as the chance that all of the injectors went bad at the same time is pretty low (unless you clogged them)
6. As suggested, take the injectors to DePaul at East Passage in Portsmouth. They can service/check them for you. I've walked in with injectors and had them check them as I waited.

Good luck!

-- Geoff

[Ereiss]

last weekend I did bleed the secondary filter until fuel came out and then cracked the 3 lines leading to the injectors but no fuel came out there. So my plan is to:

1. Change the gasket in the bowl of the secondary filter and the filter while I am in there.
2. Bleed the secondary filter through the bleed screw.
3. Then move up the system, first removing the feed into the high pressure pump to see if I can manually pump fuel out there.
4. From there not so sure, perhaps cracking the three lines as they exit the pump and cranking the engine to see if fuel comes out. That might indicate if it was a high pressure fuel pump problem.

sound like a reasonable approach? What have I missed?

Again, thank you for your help.

[Mike Holibar]

Ed,
the previous posts seem to have missed the hp pump bleed screw. This is a 10 mm hex head screw on the top of the hp pump just by the injector lines. Back this off one or two turns and operate the lift pump lever to pump fuel through. Keep pumping until no more bubbles. Then nip up the screw and start engine. This bleed is essential to prime the hp pump. I have never had to bleed beyond this. The one time this method did not work it gave me enpugh fuel to the pump to make me think I had cleared all the air and the engine would start and then die. This turned out to be a blocked primary filter.
Good luck,