Can’t get yanmar 3GMF above 2200 rpm under load question

DArcy

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Feb 11, 2017
1,249
Islander Freeport 36 Ottawa
Does your diesel mechanic have a high pressure pump test kit? I would test it before buying a new one.
 
Jun 15, 2012
628
Hunter 50 AC St. Petersburg
Why not take the injector pump to a re-builder and get a price for the re-build? There has got to be many of them in NJ.
 
Feb 26, 2009
591
Oday 30 Anchor Yacht Club, Bristol PA
just trying to make a point; you really can't get answers if you don't spend some money on testing tools. Or, people to do the testing, people will always try and tell you what they think based on the most expensive thing they think about because it's not their money, And... you still haven't checked the exhaust elbow? which is probably the first thing you should check, I only know what I've read from you here and you said 4 years since it was replaced? most people clean it every year from what I understand.
 
Jan 4, 2006
3,899
Hunter 310 West Vancouver, B.C.
1. got rpms to about 2600 in neutral still not great and rpms in gear 2200.
If you're only getting to 2600 in neutral, something is wrong with your governor adjust ( wrongly referred to as the throttle).

As @DeniseO30 mentioned in post #43 ALWAYS DO THE CHEAP STUFF FIRST ! ! !

1. Have you tried disconnecting the governor controller cable (incorrectly referred to as the throttle) and moved the lever on the engine by hand while under load. This will eliminate the cable as a source of the problem.
Have you tried this from post #16 or did I miss your reply ?
 
Jan 24, 2017
568
Hunter 34 Toms River Nj
unfortunately time is not on my side for this year, Mac boring tech doesn’t believe that the mixing elbow should be clogged up due to the amount of hours after it was replaced are about 30-40 hours at best. However I’m planning to remove it in the spring just to rule it out. Most likely going to have a tech look at it in the spring if I can’t easily make any adjustments on the governor. Marina Mechanic is going to look into shops in the area that can rebuild it vs new. Issue with rebuilding is labor cost. He said that most shops in my area charge minimum of roughly four hours of labor at about $100 - 150 per hour. If I don’t used one of the Marina authorized shops they will not warranty or possibly even do the service work.

They kinda get you coming and going. What a racket these people have. Like some said doesn’t matter to them because it’s not there money being spent. If I have to go the route of having a tech look at it in the spring, I’m going to run everything by my friend that is a diesel mechanic for caterpillar. Although he works on much bigger engines then this, I trust his recommendations. I don’t want to just start replacing parts unnecessarily.
looks like at the end of the day I’m going to have to spend some money after I’ve exhausted any and all quick fix solutions.
 
Feb 26, 2009
591
Oday 30 Anchor Yacht Club, Bristol PA
Talk is cheap, testing is real.
Don't be so willing to plop down your money on large ticket items until you know what's wrong.
I "think" it is the elbow or a restriction in the exhaust! It's just as easy to believe me, as it is somebody else! But you will only know by testing and inspection.
But just stop & think, how much expense are you willing to go through that have an engine that goes over 3,000 RPM when you generally only use it around 2500 rpm? At least disconnect the gov cable and see if you can get the engine to do high RPMs by pushing the lever yourself I'm guessing it will scream!
 
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Likes: Capt Robbie
Jan 4, 2006
3,899
Hunter 310 West Vancouver, B.C.
I'm starting to get the impression your investigation into this problem is about as organized as a bowl of alphabet soup.

I don’t want to just start replacing parts unnecessarily.
But that seems to be exactly what you are going to do without having a clue in hell what's causing the reduced RPM. Not even a guess as to what's wrong.

You don't want to solve any of your problems before jumping in and replacing expensive components which may not be the problem. You appear to be absolutely opposed to looking at anything simple as the cause of the problem.

replace fuel left pump with new one, still no difference :banghead:
You just installed a brand new fuel lift pump and how did that work out ?................... oh yeah, it didn't make a damned bit of difference. You still don't get it yet CHECK THE SIMPLE STUFF FIRST.

Most likely going to have a tech look at it in the spring if I can’t easily make any adjustments on the governor.
Let me get this straight now. You're going to bring in a tech next spring to have him look at your mixing elbow (which requires a grade four Reform School education) and yet you're going to try to make any adjustments to your governor that you can ? I just had a look in the Yanmar manual .......... good luck with that little adventure.

Go back and read this complete posting from start to end and see if you can formulate a plan which just might, maybe, perhaps, if you're really lucky, solve the problem of low RPM without breaking the bank.

The alphabet soup approach certainly hasn't worked so far.
 
Feb 26, 2004
21,950
Catalina 34 224 Maple Bay, BC, Canada
Also read somewhere about a little ball check valve inside the housing of the raycor inlet could be stuck.
hopefully the new fuel pump will be the answer.
You mean this one?:

Fuel Starvation and The Obscure Check Ball Valve

Fuel Starvation and The Obscure Ball Check Valve

If the check valve is stuck, no fuel pump known to man will work because there is no bypass.
 
Jan 24, 2017
568
Hunter 34 Toms River Nj
Ralph,

I formulated a plan based on the suggestions given from my friend who is a diesel mechanic and the marina technician and also the very helpful people on this forum. some of The general consensus was that The issue was likely a fuel delivery or starvation issue. Plan was to eliminate and resolve any and all issues that could be from the tank to the injectors.
1. Pick up tube needs to be replaced regardless (38 years old) don’t trust it.
Unfortunately it’s still stuck and I don’t want to force it and break it off, so letting to penetrating oils work there magic.

2. Replaced all fuel lines. they need to be replaced anyway (38 years old ) don’t trust them either, could be restricted or failing internally

3. Replaced fuel lift pump, told that the diaphragm internally could be starting to fail and could have an effect on other components such as injection pump or the governor. So for $40 remove this from the puzzle.

4. Changed the primary and secondary fuel filters even though they only have very little hours on them. Eliminate clogged filters as a possibility.
No big deal, I would have normally replaced in the spring anyway.

5. Checked all fuel supply and return lines on the engine. Eliminated any possibility of a restriction

so far I haven’t broke the bank, just my time and labor so far, and for the most part just replaced normal maintenance items. Plus set up a temporary test diesel can as a fuel tank until I can get the pickup tube out.

regarding the mixing elbow: this was replaced approximately 4-5 years ago and has very low hours on it 20 -30 at best. The old one that was replaced was actually in amazing condition, almost no buildup at all considering it was 35 years old. The only issue I really had was the external corrosion. The consensus from most including Yanmar technician is that it is highly unlikely that it’s plugged up. No overheating, no smoking issues, other than the rpms everything appears to be fine. That being said it will be investigated as a possibility hopefully this spring.

Unfortunately I am still limited as to what I can and can’t do.
I am still recovering from two major surgeries. I am just trying to eliminate some obvious things that could be the culprit along with some things that have been on my to do list.

I’m not a diesel mechanic and don’t claim to be by any stretch, however I am mechanically inclined a have fair idea how diesels work. Hopefully with some insight from my diesel mechanic friend, the marina technician and others on this forum.
I will solve this problem before calling in the big guns and spending money unnecessarily.
 
Last edited:
Nov 22, 2011
978
Ericson 26-2 San Pedro, CA
4. Changed the primary and secondary fuel filters even though they only have very little hours on them. Eliminate clogged filters as a possibility.
No big deal, I would have normally replaced in the spring anyway.
Regarding your point #4: I'm assuming that you have some kind of a Racor filter upstream of your on-engine filter. Depending on which Racor model you have, it's possible that there could be a hairline crack in the housing that is introducing air into the system. I could also imagine that the problem would not present itself at lower rpms but would show up at higher revs. If it is a cracked housing, the fact that you changed the filter element wouldn't exonerate the Racor filter as the possible culprit; in that case the filter element would have nothing to do with it.

Since you already have a day tank set up, try eliminating the Racor altogether and see what happens. This would take you no time to do and would be a very simple and potentially revealing test.

As for the governor: I don't think those are especially failure prone, though it's certainly possible. But they are fairly complex and it is possible to really mess things up.
 
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Likes: Capt Robbie
Jan 1, 2006
6,071
Slickcraft 26 Greenport, NY
... it's possible that there could be a hairline crack in the housing that is introducing air into the system. I could also imagine that the problem would not present itself at lower rpms but would show up at higher revs. If it is a cracked housing, the fact that you changed the filter element wouldn't exonerate the Racor filter as the possible culprit; in that case the filter element would have nothing to do with it.
This reminded me of an experience I had with a boat while helping transport it. It would lose power at higher RPM. A mechanic found that a sensor (I think on the fuel filter) was cracked. The sensor has a plastic housing including threads which people tend to over tighten and thereby crack it.
I have no expertise in diesels and am not saying this is the OP's problem, but maybe this experience will prove helpful to someone sometime.
 
Feb 26, 2009
591
Oday 30 Anchor Yacht Club, Bristol PA
This just keeps going in circles with he she "thinks" But again, to get real answers, someone needs to use instruments, meters, gauges,
I'm Not even a diesel mechanic but I know enough to suggest checking fuel pressure, fuel vacuum, injector pressure, actual RPM, exhaust back pressure. Lever & cable travel.

I do know the new cable on my Governor lever doesn't have enough travel to move the lever "all the way"