Replacement Of Fuel Injectors For Yanmar 3GM30

[NCboatrx]

You are not going to work on the injection pump yourself. I suggest that you take it to a shop that does diesel injection equipment repairs if you want it to work properly.

[Charlie]

I have never taken an injection pump off so take this with a grain of salt but ... since no one else is jumping in. Make sure to mark the pump and the motor with a center punch so that you can reposition the timing of the pump in the correct place. My guess is that the Biodiesel may have eaten away at some of the seals in the injector pump.

[Badsanta]

I was told that yanmar does not recomend the use of biodiesel in the 3gm30 I dont know the reason.

[terrylad]

Originally Posted by NCboatrx

Terrylad, I suspect that your injection pump needs attention. The starter motor working hard is the clue as your injection pump has a device that advances the timing and I suspect that this is stuck. This will also account for all the running issues that you are having.

After pouring over the manual diagrams, it seems to me that TIMING is only controlled by the # of shims underneath the FI pump. The thing that varies the FUEL RACK, apart from the throttle is the governor, which is dependent upon the two governor springs and the speed of the crankshaft. The counterweights change with rotational speed, moving a collar which is gripped by a claw to a governor shaft that varies the FI fuel rack to keep the rpm constant under varying load.

IF.......the governor shaft is binding with not enough spring tension to allow the shaft to keep up with rpm variation, could it allow the FI rack to go to full fuel conditions intermittently...?, which would conform to my symptoms.

I noticed early in the season that the STOP shaft was binding, leaving the returned control panel stop knob halfway out after pulling it out to stop the engine. Working it in and out relieved the binding. If THAT shaft suffered binding, perhaps the governor shaft has the same problem. The trouble is....how do I exercise it without pulling the timing cover off (crankshaft pulley, water pump">raw water pump, alternator, FI pump)....

Somehow I don't think its the FI pump. But I should pull the damned thing out anyway, see if I can feel any binding on the rack lever and take it from there....

Waddya think?

I'm real tired of working on this thing on the mooring, but I'm sure learning a lot.....

[Navicula]

I pulled my injectors out this year and had them tested.......then rebuilt, there is really no reason to purchase new ones.

while i was able to pull the injectors out the seal remained in the engine, I asked my injector rebuild guy how to get them out.......he was happy to show me.......
he told me to get a TAP from my tap and die set and thread it into the seal,.......then pull it out............it worked like a charm for me....

[DotDun]

Originally Posted by terrylad

Looks like we're on to something at last. I'll pull the injection pump and take a look.

I guess that losing timing by pulling the pump would be an issue, having never done it before, so I plan to go by the book taking it out and photographing the position of the slider to reproduce when I put it back.

Any advice on fiddling with this piece of contankerous equipment? I feel like I'm doing heart surgery.....

Originally Posted by terrylad

After pouring over the manual diagrams, it seems to me that TIMING is only controlled by the # of shims underneath the FI pump. The thing that varies the FUEL RACK, apart from the throttle is the governor, which is dependent upon the two governor springs and the speed of the crankshaft. The counterweights change with rotational speed, moving a collar which is gripped by a claw to a governor shaft that varies the FI fuel rack to keep the rpm constant under varying load.

IF.......the governor shaft is binding with not enough spring tension to allow the shaft to keep up with rpm variation, could it allow the FI rack to go to full fuel conditions intermittently...?, which would conform to my symptoms.

I noticed early in the season that the STOP shaft was binding, leaving the returned control panel stop knob halfway out after pulling it out to stop the engine. Working it in and out relieved the binding. If THAT shaft suffered binding, perhaps the governor shaft has the same problem. The trouble is....how do I exercise it without pulling the timing cover off (crankshaft pulley, raw water pump, alternator, FI pump)....

Somehow I don't think its the FI pump. But I should pull the damned thing out anyway, see if I can feel any binding on the rack lever and take it from there....

Waddya think?

I'm real tired of working on this thing on the mooring, but I'm sure learning a lot.....

Timing of the IP is not a problem, be careful when removing it not to damage the shims underneath it and simply use the same ones putting it back together. No need to re-time it unless you use a new/different pump.

The critical part of removing/re-installing the IP is getting the governor arm lined up with the pin on the fuel rack. In the 3GM30, there is only a fork on the governor arm that the pin of the fuel rack sits in, no keeper, no circlip. There is an inspection plate on the block you need to remove for viewing that the governor arm/fuel rack connection is correct. Failure to get these mated properly can cause the engine to run out of control and blow up. This is the only fuel control on this engine.

I'm would be ready to stuff a heavy rag into the air intake at first startup just in case.

My pump just needed cleaned (yes, diesel just sitting will varnish like gas) and re-calibrated. As others have said, take the pump to a professional. My engine ran like new afterwards, the pro charged ~$100.

[terrylad]

Originally Posted by DotDun

Timing of the IP is not a problem, be careful when removing it not to damage the shims underneath it and simply use the same ones putting it back together. No need to re-time it unless you use a new/different pump.

The critical part of removing/re-installing the IP is getting the governor arm lined up with the pin on the fuel rack. In the 3GM30, there is only a fork on the governor arm that the pin of the fuel rack sits in, no keeper, no circlip. There is an inspection plate on the block you need to remove for viewing that the governor arm/fuel rack connection is correct. Failure to get these mated properly can cause the engine to run out of control and blow up. This is the only fuel control on this engine.

I'm would be ready to stuff a heavy rag into the air intake at first startup just in case.

My pump just needed cleaned (yes, diesel just sitting will varnish like gas) and re-calibrated. As others have said, take the pump to a professional. My engine ran like new afterwards, the pro charged ~$100.

Thanks, Dotdun. The IP is out after releasing the heat exchanger, alternator, FW pump and the thermostat housing to gain clearance. The fuel rack lug position you pointed out helped a lot. The IP won't come out of its hole unless the governor lever is moved back so the lug clears the casting. Had me puzzled for a while until I realized that the little inspection plate was underneath the stop link mount. Mirror worked wonders. Now I'm waiting to have the IP rebuilt and calibrated when the local diesel shop opens up after the long weekend.

[Ex-Calif]

Originally Posted by terrylad

I pulled the injectors (quite easily as it turns out) and had them pop tested at a local diesel garage. They all tested OK. Put it all back and ran fine for 1/2 hour under load, then back it came.

<snip>

No change. The symptoms now appear after 10 minutes of warmup. The engine runs fine at 3K rpm and then starts choking itself, rattling like mad with plumes of blue/white smoke out the exhaust. Quickly shutting back the throttle allows recovery, and the exhaust spits out black fluid (unburnt fuel?) for a second or two and then the engine runs smoothly until I take it over 2K rpm.

I hate to be the doom and gloom guy but "intermittent" FI pump failures are somewhat unusual. Periods when "cold" of normal operation followed by failure when warm is a possibility but could be something worse.

Repeatable loud "clackety" noises when warm and under load, followed by black sludge out the exhaust and recovery at idle sounds like engine mechanical failure.

And when warm/hot and under load it could be bottom end.

I would pull the oil filter, cut it open and look for metal.

I hope I am wrong.

[terrylad]

Originally Posted by Ex-Calif

I hate to be the doom and gloom guy but "intermittent" FI pump failures are somewhat unusual. Periods when "cold" of normal operation followed by failure when warm is a possibility but could be something worse.

Repeatable loud "clackety" noises when warm and under load, followed by black sludge out the exhaust and recovery at idle sounds like engine mechanical failure.

And when warm/hot and under load it could be bottom end.

I would pull the oil filter, cut it open and look for metal.

I hope I am wrong.

I hope you're wrong as well. I'm having trouble seeing how it could be the bottom end, or a problem on the crankshaft appearing as the engine heats up. Crankshaft bearing issues usually result in heavy knocking that would be there whether the engine is hot or cold.

The loud clacking noise that I have could sound like a severed piston top or a dropped valve, but that, too would be permanent. The engine runs fine under load at 3Krpm for 10 minutes or so, then develops that distinctive clacking sound, blowing smoke, missing beats etc. If the injector pump was sticky, it could cause this symptom - timing out of whack with fuel dumping into the cylinders.

[Ex-Calif]

Yeah - It all depends on the sound. Hard to tell what it sounds like on the internet.

But I have had motors quiet with no load and cool oil (high viscosity) that made noise at high load and hot oil.

When it gets to the knocking point bearing material will definitely be apparent in the filter.

I really hope I am wrong.

[DeepFrz]

Could it be a valve sticking after it gets hot and you run at higher revs. Slowing down might allow the valve to work normally. A weak valve spring could cause that.

[perchance]

My moneys on the governor.

[Dragon Lady]

Hmmm, sounds very similar to the issue I'm experiencing on my 3GM30, have you had any clogging in your fuel filter?
I've spoken to our local diesel mech whom is highly regarded and he told me it sounded like a clogged fuel filter.
I checked and sure enough it was clogged, so I replaced it.
Unfortunately the issue is still there so he suggested getting the injectors tested and repaired.
I spoke to the injector guy whom is also well regarded and he told me that it might help but may not be the cause.
So my current plan is to check all the fuel line banjo fittings first before pulling the injectors.
I have also been told it is unlikely to be the injector pump.

There was talk on another forum that said that high oil level in the sump can cause this.
Thanks all for sharing your views and experience.

[terrylad]

Originally Posted by Dragon Lady

Hmmm, sounds very similar to the issue I'm experiencing on my 3GM30, have you had any clogging in your fuel filter?
I've spoken to our local diesel mech whom is highly regarded and he told me it sounded like a clogged fuel filter.
I checked and sure enough it was clogged, so I replaced it.
Unfortunately the issue is still there so he suggested getting the injectors tested and repaired.
I spoke to the injector guy whom is also well regarded and he told me that it might help but may not be the cause.
So my current plan is to check all the fuel line banjo fittings first before pulling the injectors.
I have also been told it is unlikely to be the injector pump.

There was talk on another forum that said that high oil level in the sump can cause this.
Thanks all for sharing your views and experience.

Good luck with the fuel lines. Make sure you replace all the copper washers with new ones on the banjos. They're cheap. There's a great video on cleaning the injectors - just the bottom half - on youtube, search for yanmar injector cleaning.

I've run my engine from a bucket of clean fuel to the lift pump - same symptoms. I've removed and tested the injectors (OK) - same symptoms, I've tested the thermostat - same symptoms, replaced engine filter and racor - same. Acid washed the heat exchanger and the exhaust elbow - same.

Next step is if the IP rebuild doesn't solve the problem, (the IP is still at the shop) I'll have the injectors rebuilt or replaced...The engine is clean and has always run sweetly on light duty, although I ran it on biodiesel last year. I know its controversial, but a lot of local Yanmar powered launches have used it with no problems. Mine's only about 5 years old.

[Dragon Lady]

Thanks, yes I know about the cooper washers.
Gee I hope the pump rebuild works for you but then again I hope I'm not up for one too.
I think the oil level relates to loading up the engine not causing oil to bypass the rings.