Yanmar 2qm20 not starting troubleshooting

[WestcoastCrown]

Good afternoon, I have a Yanmar 2QM15, which is essentially the same engine, only the 15 HP model. I've owned it for about six years and been through many "adventures" in starting and running it.
The thing that I notice is that the washers for the banjo bolt in the return line to secondary filter that is mounted on the engine are incorrect. That bolt, as stated by jimbunyard, should have a crush washer above and below the fitting.
With your observation that it ran, and then after shutting down the secondary filter is empty, makes me believe you have an air leak at that joint. Coupled with fact that it will not restart after running well and I think you have found the problem

The slightest air leak in the fuel system will stop these from starting. I have had to recheck filters and connections after a filter service when it wouldn't start and always it's an air leak in the fuel system.

Two changes we made have worked well for some time now:1) we use a 12volt diesel fuel pump instead of the mechanical one. It it wired so it comes on when the key is turned on and 2) re-routed the fuel return line from the secondary filter back to the fuel tank. It is "Tee-ed" into the vent line just above the tank. We did this on the advice of our diesel mechanic and both were great suggestions.
With the electric pump, you also now have a self bleeding system for filter changes and air problems.

It seems you are very close to solving the problem and will not have to spend a lot of money in the process. I had several problems with my engine when I first bought the boat and this forum was invaluable in solving those issues.
Good luck!

[WestcoastCrown]

Just as aside, I always start my 2QM15 with the throttle wide open. I pull it back as soon as it starts to catch and settle into an idle. It was suggested to me and works like a charm.
The electrical issue you have is a separate one. We had the same last year and replaced the alternator. Problem solved- by an expert, not by me.

[Cheechako]

Originally Posted by thesauvage

Quick Update:

I'm at the boat right now, and gave the engine a good spray with the starter fluid.

VIDEO: https://youtu.be/W1-te1gGIro


The engine started up and fired promptly, and died shortly after.

Fuel delivery seems to. be the Problem, right?

My guess is yes, fuel. It's running off the spray initially. A couple things:
-Is there a clear bowl on a fuel filter? How does the fuel look? It may be clear and orange looking or it may be cloudy and full of growth. Or unscrew the engine filter and pour the fuel into a glass jar to look at it.
-If full of floating junk and growth, change the fuel filter and engine filter also. You may even find a big lump of fungus in either that looks like latex rubber.
-For a test run you could start it after cleaning those, but should probably have the fuel in the tank polished or removed shortly.

-It may not be dirty fuel though, I've ran engines that sat that long with poor looking fuel. As likely as not you should remove the injectors and have them rebuilt... WHY? Because without any use, the tips often corrode or rust a bit making the spray pattern bad.
-If you do the injectors, maybe spray liberally in the cylinders while you are waiting for them. As mentioned that may help make sure the rings etc are loose and so you dont break a ring on initial start up!

[thesauvage]

Originally Posted by WestcoastCrown

With your observation that it ran, and then after shutting down the secondary filter is empty, makes me believe you have an air leak at that joint. Coupled with fact that it will not restart after running well and I think you have found the problem

The slightest air leak in the fuel system will stop these from starting. I have had to recheck filters and connections after a filter service when it wouldn't start and always it's an air leak in the fuel system.

It seems you are very close to solving the problem and will not have to spend a lot of money in the process. I had several problems with my engine when I first bought the boat and this forum was invaluable in solving those issues.
Good luck!

thank you very much for your input.
What would you advise to do, despite the regular bleeding procedure, before replacing the lift pump?

Good hint with starting with full throttle, I'll apply it for my next starting attempts.

Absolutely correct! The help and advice I've received on this thread so far is simply amazing!

[Cheechako]

Originally Posted by thesauvage

thank you very much for your input.
What would you advise to do, despite the regular bleeding procedure, before replacing the lift pump?

Good hint with starting with full throttle, I'll apply it for my next starting attempts.

Absolutely correct! The help and advice I've received on this thread so far is simply amazing!

"Westcoastcrown" above makes good points.
I don't know that I would jump to replacing the lift pump. I'd probably buy a cheap electric car pump and try it first if it came to that. The manual pumps do go bad, but not all the time.. They do feel like they wont pump manually after a couple of hand pumpings. An electric pump will a llow you to do filter and engine priming in the future anyway.
-Fill the filter housing then close it up.
-Your fuel filter from the pic you posted doesn't look very dirty.
-The simplest way to bleed the engine is to crack the injector nuts one at a time and turn the engine over until the fuel spurting is a steady stream without bubbles. Put a rag on the engine under the injectors to catch the fuel. This has always worked for me with Yanmar's without doing anything else.
-If it ran, it should run again I would think.
-Don't turn the key off before stopping the engine, some boats are wired so this will kill the alternator...

[thesauvage]

Originally Posted by Cheechako

-Is there a clear bowl on a fuel filter? How does the fuel look?

As likely as not you should remove the injectors and have them rebuilt... WHY? Because without any use, the tips often corrode or rust a bit making the spray pattern bad.

The fuel looks fine to me. The engine did ran on it after a few starting attempts, (please see my other posts on this thread.)

I'd like to pull the injector, but they seem to be pretty stuck and rusted. I'm not sure they will move easily.

[Wotname]

Originally Posted by thesauvage

.......

I'd like to pull the injector, but they seem to be pretty stuck and rusted. I'm not sure they will move easily.

Most likely they will be very difficult to remove - more later.

[WestcoastCrown]

I would agree with Cheechako, don't replace the mechanical pump, odds are it is fine. Buy a 12 volt diesel pump and place it into the fuel line after the tank. I used the Mr Gasket Part Number -12D micro pump with filter, costs about $50 here in Canada.

In order of how I would do it:
-replace all of the crush washers on the secondary (engine mounted) filter
-replace all rubber fuel lines, if they are four years old
-install 12 volt diesel fuel pump and bypass mechanical pump
-bleed system using 12 volt pump ( if wired to key switch, unplug multi contact connector behind the engine panel to stop alarms from sounding while running pump to bleed) reconnect connector before trying to start
-bleed at injectors - referenced above with YouTube videos
-Cross fingers and try to start
- if it starts, run and then wait 24 hours to try again to see if an air leak lets the fuel drain creating air bubble.

We also solved some issues by installing new injectors. It may have been cheaper to have them serviced, but opted to go with new ones at that point.

Also, the warmer the ambient temperature the easier it is to start. We use a 60 watt heater permanently mounted to the oil pan that runs off the shore power to keep the engine slightly warm.

[thesauvage]

Originally Posted by Wotname

Not really - anything is possible I suppose but it hard to imagine how you could damage it inadvertently.

your battery must be getting flat by now unless you have some external charger.

More later.

I'll bypass the pump with a 12V fuel pump, and exchange all fuel lines.

I have an external charger, and shore power available.

[Wotname]

Ric

Long post alert…

You have received quite a bit of advice so far and most of it is good (IMO). There is nothing here so far that I disagree with although some of it is more pertinent once you have solved your starting problems.

Disclaimer - I am not a professional mechanic (diesel or otherwise), I am just someone who is interested in the smaller older marine diesel engines (say less than 50 hp) and has spent a fair amount of time rebuilding and getting older engines running again (especially Yanmar). You might say a bush or shade tree DIY mechanic. As well, in the past I had to professionally diagnose complex electronic defects remotely in the aviation and oil/gas industries.

There are professional mechanics on CF and their advice varies from very good to excellent - again IMO. You are in good hands when members like A64 and JimB (plus others) offer advice.

So bearing in mind the disclaimer here are my thoughts again and what I would do in your situation. This isn’t the only way to attack your engine problem, it is just one way and one that has often worked well for me in the past.

It is often stated, to get a diesel to run, you only need three things - fuel, air and compression. This true but to get it to start you need a fourth,which is a sufficient rate of change of compression or more simply put, good starting rpm when the starter motor is engaged.

Let’s look at the four requirements individually and look at methods to ensure they are met to ensure a start.

Compression - right now we know you have enough compression for the engine to run (unloaded) although we don’t know for sure if you have enough for achieve a start. Why the difference - when the engine is already running, the combustion chamber is already hot but it is cold when you are trying to start it. There are many things that causes a partial loss of compression (cylinder / piston / ring wear, burnt valves etc) but only one that is easy to check - that is the valve lash or tappet clearance. Given the likely history of the engine, I would check the tappet clearance as it easy to do. It should be 0.2mm (8 thou “)

Starting RPM - this is essential to get a start. Why, because if the rate of change of compression is too slow, it doesn’t heat the air hot enough during compression to ignite the fuel. To my ears, your engine sounds a little slow but not hugely slow. This indicates a possible electrical partial defect in the starter motor circuit but there are two easy ways to determine if this is really a problem or not.

The first is to set the throttle to say halfway, spin the engine over decompressed using the starter motor and after say 3 or 4 seconds, re-engage the decompression levers and if the engine starts, you have low starting rpm problem. Why, because when you spin the engine up decompressed, you are storing momentum in the flywheel and this stored momentum helps on keeping the rpm high enough when the levers are re-engaged. This method is a quick, simple and very definitive way of analysing the starter motor performance or otherwise.

The second way is to introduce some fuel into the engine that ignites at a lower temperature; typically some engine starter fluid. This has a good percentage of ether in it which ignites at a much lower temperature than diesel. However re-read the cautions posted up thread by A64 and JimB. This is great stuff in the hands of the experienced but can cause damage if mis-used. Another older method is to use a small amount of petrol (gasoline) in lieu of the staring fluid. In fact the earlier Yanmar Y series had a small capped port on the inlet manifold purely for that purpose. Only use a few ml (5 at the most i.e. a teaspoon full) and toss it into the inlet manifold a few seconds before attempting to start. Again tread carefully!

Of course using starter fluid isn’t a definitive method to prove a low staring rpm issue as it might also work because of a full problem (see below). To prove a low staring rpm problem when using starter fluid, first try starting using a spray bottle (atomiser bottle) of diesel. Spray a quick shot of diesel into the air intake, if the engine fires, you are looking at a fuel problem but if it doesn’t, then try starting fluid and if it now fires, you are more likely to looking at low starting rpm.

Air - if the air cleaner element is removed, inlet manifold is clear, and the intake valves are operating normally, then the air will be sufficient to start. Maybe not sufficient to run properly under load but sufficient to start.

Fuel - there’re many many reasons why the fuel might be the issue (air, age, delivery, lift pump, fuel lines injector pump, throttle rack, injectors etc). Rather than spending a lot of time looking at each and every aspect, I much prefer to rule it in or out early on by providing a separate source of new fuel feed directly into either the engine mounted fuel filter or directly into the injector pump. Some say you shouldn’t provide unfiltered fuel to the injector pump but I don’t think a 10 or 20 ml of clean fuel will ever cause a problem to an already old engine. I use a container (say 1 or 2 litres) of clean new fuel, a clean clear vinyl tube (8mm / 5/16" IIRC) tapped to the side of the container with the other end going to the filter (or to the injector pump inlet). Use gravity and siphon and bleed the air out of the tube right to the injector pump inlet. This ensures you have a supply fuel to the inlet of the injector pump. Often you don’t have to bleed the high pressure side to the injectors but you might have to. Especially on the Yanmar QM series as they have quite long high pressure lines (about 900mm - 3’) and if they are full of air, they won’t self bleed IME. There is knack to bleeding the high pressure side and youtube can explain better than me.

To recap and simplify the above, I would (in order) check the tappet clearance, provide clean fuel direct to injector pump, bleed it and try a start by using the decompression levers. If no start, then use some starter fluid. If it starts but doesn’t run, keep it going with a few small squirts of diesel from a spray bottle directly into the air intake.

Using the above explanations work out what is missing - air, compression, starting rpm or fuel and fix that problem first.

Some words about the injectors - IME, they can be very difficult to remove on old uncared for Yanmar small series engines. They are nicely arranged to catch any water, salt, dirt etc and hold the contamination forever - better put, they rust in place. Ideally you should pull them and observe the spray pattern but often that isn;’t possible without some serious effort, tooling and experience. A poor spray pattern will make the engine hard to start but usually they work well enough to keep the engine running once started, especially if the engine is unloaded. A poor man’s injector cleaner is to mix some ATF into the diesel (say 5%) and run that though the engine for a few hours. If that doesn’t help and they won’t come out, you will have to resort to removing the head and taking it to a good diesel engine shop to get them out.

Getting close to the end now, what to do once you have gotten to the point where the engine starts and runs OK unloaded.

The engine now needs a good workout (Italian tuneup).

First - pull the mixing elbow and inspect for blockage (both to the water and to the exhaust). Fix as required. This must be done.

Provide clean fuel with either an injector cleaner or some ATF added

Second - tied to the jetty, run the engine in gear and slowly bring up the rpm to around 2000 (or just below mid throttle if you don’t have a tacho). After five or ten minutes, increase the rpm to maximum unless you are getting black smoke before WOT (wide open throttle). Keep the throttle just below black smoke or at WOT if no smoke. Run it for 1 to 2 hours like this (assuming there is no overheat alarm - and there shouldn’t be). It takes about 40 mins for the oil temperature to stabilise.

When you are ready to shut down, bring the throttle back to about 1/4 and let the engine cool down for 10 minutes (still running). Then put it back into neutral and race the engine about 5 times i.e. taking it to WOT and back to idle). Shut the engine down and when cooled off, change the oil and oil filter.

Finally drain the raw water in the exhaust manifold. This may prove impossible if it hadn’t bering done regularly. IMO, it is design fault of the QM series. It is OK if is done regularly but if not, the bottom of the water jacket quickly clogs up with calcium carbonate and rust. Depending on how bad it is, it can be cleaned.

Hopefully I haven’t left anything out or got anything wrong; if I have, I expect other readers will correct the record.

[Wotname]

Originally Posted by thesauvage

....... Is there a way to determine if the fuel is still usable?

-.........

This might be of interest, I found this information some time back in an old Yanmar manual on how to field check diesel.

1. Fuel that is extremely odorous and smokey contains a large amount of volatile components and impurities.
2. Fuel that emits little smoke when used in a lamp is of good quality.
3. Fuel that emits a crackling sound when soaked in paper and ignited contains a high water content.
4. If a transparent film of diesel is squeezed between two pieces of glass, the water content and impurities can be determined.
5. If the fuel contains resin or carbon black particles and impurities will appear when fuel and sulphuric acid are mixed in equal parts.
6. Discolouration of litmus test paper indicates the presence of acids.

[Wotname]

Ric,

Once you have the engine starting, running and tuned (as described above), you must replace the engine anodes and you should really really de-scale the block, head and exhaust manifold raw water passages. There is some information somewhere on CF that I have posted in the past but if you need it (and can't find it), let me know and I will dig it up.

It isn't hard but it is somewhat time consuming.

A raw water cooled engine should be de-scaled every couple of years and the anodes must be replaced as required (often yearly).

[thesauvage]

Wow! Thank you very much for the very detailed description and informations Wotname.
Really appreciate the effort. I'll report back with the results from my further testing.

Thank's everybody for your help so far

[Wotname]

But wait - there's more

Keep an eye on the corrosion on the injector lines where they cross the front of the motor (see red circle). This is the point they are most likely to corrode. Although they have a 2mm wall thickness, they can get pretty thin at this point.

[thesauvage]

First of all, Thanks to everybody, that contributed on this thread. Wich really helped me solve my engine problem.

Update:

I was back at the boat today and wanted to rigg the direct fuel feed to the HP pump. It was then, I noticed that I could rotate all fuel lines, despite of the attached hose clamps.

So I decided to inspect ALL fuel lines, before anything else. I went ahead and took off all fittings cleaned them. While re-attaching the hose clamps, I even found one, that was completely broken, so the fuel line was basically just sitting on the connector nipple.
After I was done fiddling all hoses back on again, I throughly bleed the whole fuel system (from primary fuel filter up to the injectors).

I decided to give it one more try, before deviating to a direct fuel feed to the HP pump, and.... IT STARTED!
Without any hassle, starter spray or decompression lever use. It cranks for about 1 second and fires right up.

Video 1: https://youtu.be/1e8Os7KF9NE

But the Charge alarm keept sounding throughout the whole time. I also noticed that a loud squeeking noise is coming from the alternator, while the ignition key is in start position. On top the engine seems to run less smooth when the key is in ON position. Please see video:

Video 2: https://youtu.be/5MY8UkgeefE


I suspect the alternator is not wired correctly, or damaged/dead? Possible? What do you guys think?