Rough running Yanmar 1GM10

[Igetit]

I have an 02 Hunter 270 with the Yanmar 1GM10 diesel, which I have owned just over a year. She starts immediately, runs fine, but on the last two outings after running under power back to the marina (15-20 minutes near full throttle), she runs rough and will barely idle. Today I ran the engine for about 45 minutes and when throttling back to enter the marina, she died at idle. Started her back up and she would barely run, then started banging every few strokes. I sailed her into the slip on the jib and am scratching my head. A slip neighbor recommends a bottle of injector cleaner, but I would like other opinions.

The only maintenance I have performed in the year I've owned her is an oil change and air filter cleaning. She has an 11 gal diesel tank and consumption is very low as I'm on an inland lake. Could it be fuel contamination/condensation? (Wouldn't that make it run rough ALL the time, not just after running an extended time at higher rpm?)

Any thoughts appreciated.

 

[weinie]

change yer fuel filter(s).

 

[Alan Gomes]

I have an 02 Hunter 270 with the Yanmar 1GM10 diesel, which I have owned just over a year. She starts immediately, runs fine, but on the last two outings after running under power back to the marina (15-20 minutes near full throttle), she runs rough and will barely idle. Today I ran the engine for about 45 minutes and when throttling back to enter the marina, she died at idle. Started her back up and she would barely run, then started banging every few strokes. I sailed her into the slip on the jib and am scratching my head. A slip neighbor recommends a bottle of injector cleaner, but I would like other opinions.

The only maintenance I have performed in the year I've owned her is an oil change and air filter cleaning. She has an 11 gal diesel tank and consumption is very low as I'm on an inland lake. Could it be fuel contamination/condensation? (Wouldn't that make it run rough ALL the time, not just after running an extended time at higher rpm?)

Any thoughts appreciated.

I have an Ericson 26-2 with a Yanmar 1GM; I've had the boat for a little over a year. The first thing I did when I got the boat was to change any and all regular maintenance items: oil filter, air filter, fuel filters (primary and secondary), anti-corrosion zinc, impeller, etc. That way, I would be starting from a known basis and I can take care of the ongoing, regular maintenance from there.

 

[Ken13559]

Any black smoke?

 

[Igetit]

No black smoke - a trace of white once in awhile.

 

[kloudie1]

Sounds like some overheating symptoms a little.. Have you verified that the overheat alarm is connected and working? Water pump impeller good? Plenty water flow? Changing the fuel filters and bleeding the fuel system is a good idea too..

 

[Igetit]

I have not yet, but I will. You guys have given me several things to investigate and I appreciate the help. Will keep you posted.
Thanks,
Paul

 

[Nelsonhow]

Keep is simple first

1) Replace primary fuel filter which is usually on the wall of the engine compartment.
2) Replace secondary fuel filter on engine.
3) Bleed fuel system and check for fuel leaks.

If 1, 2 and 3 fails check that you have good clean fuel and no clog of diet in the fuel. Pickup tube in the tank.

 

[rardiH36]

1) Replace primary fuel filter which is usually on the wall of the engine compartment.
2) Replace secondary fuel filter on engine.
3) Bleed fuel system and check for fuel leaks.

If 1, 2 and 3 fails check that you have good clean fuel and no clog of diet in the fuel. Pickup tube in the tank.

Re #3 form Nelsonhow. I'll recount my experience several years ago. I let the fuel level in my tank get too low. Sucked some air while the boat was rocking which stopped the engine. Anyway, the episode prompted me to tackle the long overdue tasks of replacing all the fuel hoses, clamps, and the banjo crush washers along the engine's fuel pump, filter and injector connections.

After, I noticed that the engine was running quite a bit smoother than before. Particularly at idle. I think that there must a been small leak somewhere that was allowing some air into fuel flow causing inconsistent pressure at the injectors which translated into rough performance.

Your symptoms are more severe than mine, but the fuel delivery components are worth a check. Particularly anywhere before the pump where fuel is sucked rather than pushed. Any small leaks along this part of the fuel delivery system (such as a small crack at a bend in the hose or a bad seal at the Racor type filter) can suck air into the flow. Since there is no pressure along the pre-pump section, a fuel leak might not be evident.

 

[Steve Dion]

Check out the fuel pickup tube. Some models had a screen on the tube to prevent larger contaminates from getting into the filter/s. You can remove this screen.

IF there is stuff in the screen you may want to consider removing all of the fuel from the tank and cleaning out any sediment in the tank.

Also be sure that o-ring on the fuel fill is good (just replace it). That is a good place to get water into the tank.

You probably have a small filter (like a Racor 110) you may want to consider something like a Racor 120 if it turns out to be a filter issue.

You only have one injector so you may also consider have it checked out at a diesel shop. There are several things (all the above posts) you can do before you revert to that.

 

[Igetit]

Just wanted to offer an update on this since so many of you took the time to help me out:

1) I started by ruling out an overheating issue due to a bad impeller, expecting to find it chewed up or degraded from previous year's antifreeze. The part appeared to be fine, so I swapped it out anyway, and now I have a spare and the knowledge of where it is, how to change it, and what it does. Also cleaned the raw water intake filter and verified good exhaust water flow from the port at the stern.

2) Moving on to the fuel delivery system, discovered that my boat does indeed have primary and secondary filters, so I ordered the replacements, found an excellent video series on YouTube showing the proper replacement technique, including the little manual fuel pump valve (always wondered what that thing was for...), and swapped those out on Saturday morning. Filling the new filters with clean fuel before reinstalling seemed to eliminate any need to bleed the lines, as the engine started right away. Throttle response has returned to normal, and it idles smoothly after running at speed for some time, out of gear.

3) Next I took the boat out for a spin to test the engine under load. Initially it seemed to generate max rpm, but then started falling off and missing slightly. I throttled back to half and did a quick 180 toward the marina entrance.

Next steps: After researching a few websites and other threads here, I am planning to rule out reduced flow through the mixing elbow, and also contemplating draining my entire fuel tank, cleaning any deposits from it, and refilling it with fresh fuel.

I think it will be necessary, given the relatively high capacity and low fuel burn, for me to maintain a fairly aggressive fuel maintenance program to prevent diesel bug and other maladies.

I know this is all probably familiar to many of you, and basic diesel maintenance, but I am laying out my story for those following behind on the diesel ownership path. I really like doing the work myself and learning all the systems, and appreciate the patience of wisdom of those who have helped.

Here is the video on changing fuel filters that I found especially helpful - http://www.youtube.com/watch?v=ETfjGSnmCeg

Thanks,
Paul

 

[Alan Gomes]

Regarding eliminating a contaminated fuel tank as the source of your problem: As a quick and easy way to diagnose this, get an inexpensive "day tank," such as a portable fuel tank you'd use with an outboard motor, and run your engine from this source. Remember that you'd also need to plumb the return line to the day tank as well. Or...just make sure that you have adequate empty space in the main tank and leave the return line plumbing alone. But in the latter case, just be aware that the level in the day tank is going to drop more quickly than otherwise since the fuel would not be returned to it from the return line. If all you need to do is a short test then this particular issue may not matter.

 

[Sailm8]

Don't forget the pick up tube in the tank. I had a 1GM that got clogged and showed the same problems.