Yanmar 3qm30 NO START ISSUES

[Wotname]

Hmm... given all that you have posted so far makes me think the IP wasn't re-installed correctly.

Particularly that you managed to remove it (presumably without swearing) given the lack of access you mentioned. I had the devil's own job removing regulator spring / regulator lever / governor lever/ governor link and I had good (perfect) access.

However it maybe simply a IP rack externally stuck - it doesn't take much but consequentially it doesn't take much to free it either without dismantling the IP itslf

[Wotname]

If the IP was previously removed (and/or worked on), I would be wanting to check the timing when refitting unless it can be confirmed it was OK before you removed it this time.

[Wotname]

Maybe the following pictures could be helpful.

This is a 2QM20 IP where the rack was not moving before removal. It is now moving to the same specs as in the manual and this was achieved without any disassembly of the IP, just good but gentle meaning on the outside! Of course, I don't anything yet about the condition of the internal sections.

Maybe you can be lucky and only have an external problem or maybe someone has messed internally with the IP and mis-assembled it.

[Chayal]

It was tight. I had a magnet tangling In the work area, mirror and flashlight.

There was still many swears...

Just enough room to swing that pump out which was nice.

Looking over the manual, it seems like straightforward disassembly other than the springs.

It looks similar to a valve spring retainer in a gas engine. I imagine disassembly is to push in the spring and turn the spring retainer Until it comes off of the plunger?

The yanmar service manual says to remove but doesn’t specify.

[Chayal]

The timing will definitely be confirmed and assured when it comes to reassembly

[jimbunyard]

As par for the course here, you're being given a mix of some good and some pretty inaccurate information.

From your postings, there are several scenarios that are possible.

The engine was running fine, and was just not used anymore, and it had good fuel in it, and a good coat of oil on it, which just 'dried up' (evaporated) leaving the rack and pinions, and likely the p&bs gummed up. If there is little or no rust on it, and someone hasn't botched a reassembly after cleaning or attempting to clean it, this will probably be your best case scenario.

Just because there are scribed marks doesn't mean anything is wrong; as you've seen in the book, those marks are made whenever the pump is disassembled to aid in its reassembly.

With 600 hours on it, in this condition, if you bring it to a shop, much will depend on which shop you bring it to, and if new parts are available for the 40 year old pump. Also, you'll almost certainly have to retime the engine by adjusting the shim pack, especially if they change any internal parts.

Another scenario is that the engine was left with bad fuel in it, in which case the lap fit internal parts will be corroded and have to be replaced, so the point is moot: it has to go to the shop, and you'll have to deal with retiming the engine when you get it back.

A final scenario is that in its time of disuse, condensation has wreaked havoc
on it, it was left with bad fuel in it and will have to be replaced entirely. Sucks to be you if that is the case.


If it were me, I'd do what you're doing; see if you can free it up. If you're uncomfortable with trying to clean it yourself, then don't. But make sure you check out the guys you bring it to before you bring it to them, and get an estimate first. My first choice, all other things being equal, would be a shop that specializes in ag equipment, but the quality of shop service in my experience can best be quantified as a crap shoot.

These little pumps are very simple, if the only problem is that it has gummed up internals, and the engine was running good when it was laid up, carefully taking it down, cleaning, inspecting and reassembling it as per the manual will be the most economical route to take, if you feel you can do it.


It can be done, and I have done it more times than I can remember.

Nothing wrong with taking it to a reputable, conscientious shop though.

[Compass790]

:I'd agree with post #21
Had the same thought as JImB about if you are not comfortable with disassembly take to workshop.
Just like to add make copies of the pages from your service manual that apply to the pump tester & take to injection shop to save them trying to find them if they aren't familiar with that pump. Will save time when they put it on the testing rig.
My guess is that parts should be obtainable as those Bosch copy pumps are common & other variants will use the same critical parts.
Don't ya just love boat engine no-rooms?

[Compass790]

Originally Posted by Chayal

It was tight. I had a magnet tangling In the work area, mirror and flashlight.

There was still many swears...

Just enough room to swing that pump out which was nice.

Looking over the manual, it seems like straightforward disassembly other than the springs.

It looks similar to a valve spring retainer in a gas engine. I imagine disassembly is to push in the spring and turn the spring retainer Until it comes off of the plunger?

The yanmar service manual says to remove but doesn’t specify.

After you have removed the bottom rollers you just depress the springs & the bottom plunger spring retainer slides out to one side.
Frm memory ( a long way from infallible lol) there should be an exploded view in the service manual. You have to study that carefully & follow the directions religiously if you are to succeed.
All the copper crush washers should be replaced.I just annealed mine but not really recommended.

[Chayal]

Hey all, just an update.

After 24 hours in a MMO soak...

So one of the plungers ended up being corroded, jamming the fuel rack in place. A spring cup was in backwards, this is more than likely the fuel leak source.

Plunger was easily loosened with a few taps with a wood dowel.

After some careful lapping, lots of cleaning, it’s all back together now. I ended up
Annealing the copper washers too ^

Engine is running now.

Thanks everyone for the help and input. These are very easy pumps to take apart if your patient, attentive to detail, and follow and study the service manual. Just like anything else of course.

[Wotname]

Thanks for the update, great outcome, well done!

[Compass790]

Glad to hear you did it,
& happy you posted the results & evidence pics
I would have replaced the rusty plunger & barrel as it may leak from there. The lap fit is trying to hold back the 2400 psi or what ever the injection pressure is.
Hope you get away with it tho.
So you were fighting two problems, bad assembly & water ingress. How did the delivery v/v's sealing faces look?
I'd strip & clean your injectors as well, actually probably just replace the nozzles anyway although possibly not with it's low hours.
Laughed you annealed the washers as well.
Saved yourself probably +$600US for a new pump

[Compass790]

I'm just wondering if the water came from the sump side?
Is your engine the raw water cooled version? Are the rollers rusty? Seems a bit strange if only one pump is rusty if water came in the fuel.
Might pay to check water pump as well. Just a thought.

[Chayal]

It’s been retrofitted for a closed loop.

No corrosion on engine side.

Oil was just filth.

[Chayal]

Picture of rollers.

[Compass790]

Thanks for posting back. Helps with diagnosis. Yep u can get things that defy your supposedly logical thought processes. Important to keep the flow of info going I think.
Roller not too bad.
If water came with the fuel nxt target is deck fill cap ( must have good o-ring) & tank. Mite need a clean. This is my thoughts from experiencing those issues.
Post back if there are any future problems please. I'm happy to learn or pass on my experiences.
I like the Pacific NW & people treated me well when I was up there.
Regards Paul