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Old 22-11-2019, 16:15   #46
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Re: Yanmar won't go beyond 2200 revs. Help!

Definitely subscribing to this one...good luck.
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Old 22-11-2019, 16:55   #47
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Re: Yanmar won't go beyond 2200 revs. Help!

Quote:
Originally Posted by Toccata View Post
127 hours from Brand New (Not rebuilt)
Gotta be something simple.......(please say yes)
I am hoping there is a gauze mesh in a banjo fitting and that this has become clogged with algae, or that my secondary fuel filter is clogged with algae. Todays job: bypass the secondary filter for a short test run, and check banjo fittings/unions
First off I don't know much about turbo equipped engines but it seems incredible it could crap out @ 127hrs
Also quite unusual that max rpm is the same in neutral as loaded. A few questions for you.
1) have you tried disconnecting throttle linkage & manually operating the fuel rack lever to see what max rpm is then?
2) is the engine using oil?
3) did the problem occur suddenly or came with the boat?

I doubt it's your fuel supply to IP after all the work you did & if fuel supply to IP pump was restricted I'd guess the max revs would be higher unloaded.
I'd be trying sailing Gals suggestion re timing if you are sure no air intake restrictions.
As wotname suggests cause of carbon build up needs to be investigated. Maybe exhaust needs to be checked too?
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Old 27-12-2019, 03:34   #48
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Re: Yanmar won't go beyond 2200 revs. Help!

Engine Yanmar 4JH4 TE Only 128 hours from new, installed in 2013.
Engine used to run properly (i.e. full rpm) according to the PO.
Changes:
New Turbo. New exhaust elbow.
New Fuel system primary Racor, secondary cartridge, fuel hoses and spotless tank (tank did have a 20mm layer of crud).
New Vetus exhaust hose and Waterlock.
Problem Not achieving full RPM (3200) in gear OR in Neutral. Reaching 2000 only.
Since the last post:
Rechecked fuel supply. Clean fuel in a clean tank connected directly to the fuel pump; No Change.
Removed the Vetus Waterlock. Connected the new Vetus exhaust hose directly to the exhaust elbow. No change.
Checked the taco with an independent gauge, both read the same.

Whats left?
Check for high tappet clearance, i.e. valves not opening fully?
Remove fuel pump, assuming some gunk got into it? Although the engine runs smoothly up to 2000rpm.
No excess exhaust smoke to speak of.
The exhaust back pressure in the manual is 20kpa. I can't buy a gauge that reads that low locally. I have made a water gauge, what water column height should I expect?
Any thoughts appreciated.
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Old 27-12-2019, 03:37   #49
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Re: Yanmar won't go beyond 2200 revs. Help!

Throttle lever at the fuel pump is reaching its full travel.
Current max rpm 2000, is obtained at about 2/3 to 3/4 throttle travel.
The remaining travel, leads to a small change in the exhaust note, slight smoke increase, hard to tell but looks blueish, but NO increase in rpm
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Old 27-12-2019, 05:15   #50
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Re: Yanmar won't go beyond 2200 revs. Help!

Original poster here. Turned out my issue was a faulty injection pump. Installed a new one. Problem solved. Injection pump specialist in Ft Lauderdale said there had been signs of water in the fuel which was odd as I had never had any water seen in tanks or Racors. But new pump works great.... back to factory specified performance.
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Old 27-12-2019, 05:39   #51
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Re: Yanmar won't go beyond 2200 revs. Help!

Hobbiehobie bear me to it. 4JH4-TE would not go above 1,600. Sent injector pump out for service, it came back noting (paraphrase) “no issues found, dirty inside, cleaned.”

I believe these pumps have an ROM limited (blocking on word) and that can malfunction.

Be careful if you intend to remove the pump yourself, there is a pit fall. I can explain if you desire. It should take an experienced mechanic 2-3 hours to remove the pump and 1-2 hours to replace. Took me a couple of days.
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Old 27-12-2019, 10:36   #52
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Re: Yanmar won't go beyond 2200 revs. Help!

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Originally Posted by boatbod View Post
Undercutter:- unloaded (neutral) max rpm is dependent on governor setting and is usually 200-400rpm higher than the max rated fully loaded rpm. On a 3600rpm engine you'd expect to reach at least 4000 before the governor would limit you.

Propellers should be sized/pitched so that the engine can attain at least the max peak nameplate rpm with wide open throttle and a clean bottom. Yanmar allowed you to exceed the max rpm by any amount, but under no circumstances are engine's to be set up overpropped and unable to attain their max.

Running an overloaded diesel will usually result in black smoke, foot in the exhaust and overheating/high EGT. It's as bad for the engine as persistent running at light loads.
Before anything else, make sure it's at full throttle, the lever must be on the stop at work.
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Old 27-12-2019, 13:15   #53
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Re: Yanmar won't go beyond 2200 revs. Help!

Thankyou Hobiehobie, for completing your story, doesn't always happen, and it's why I am still posting about my issue.
The fuel pump is probably my next guess however, does anyone know if the 4JH4 is rpm limited until it reaches normal operating temp?
There appears to be a spring loaded shaft and lever protruding from the side of the fuel pump. There is a fluid circuit attached to it that runs to the top of the motor. The pipe joins the fitting used for the hot water service coolant supply (to heat the hot water service heat exchanger coil)
My engine is currently only reaching 74 degrees.
One of my changes has been to remove the old hot water service and install a temporary bypass for the hot water heating circuit, by using a short pipe across to the other take off point for the hot water heating circuit.
I now wonder if I have an airlock there (in that short piece of pipe) and that if there is a heat sensitive rpm limiter on the yanmar stopping it reaching full rpm, until its hot and in my case, not getting hot because of an air lock in this bypass hose.
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Old 27-12-2019, 13:23   #54
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Re: Yanmar won't go beyond 2200 revs. Help!

That device you describe in the side of the engine changes the pump timing during cold start up. It works like a thermostat with a wax element that expands when hot.

You can safely disconnect it and then the engine will not have that “cold start assist” or whatever it’s called.

Mine fell apart last year and I ran for a few months without it.

But if you don’t disconnect it, And it never expands because you bypassed it, it will keep the lever back and mess with the pump timing.

I forget if it advances or retards. When I put the pump back in I was off a tooth, the engine would start but shut off as soon as it got warm and that was plug melted. So it can have a significant effect.
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Old 27-12-2019, 13:32   #55
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Re: Yanmar won't go beyond 2200 revs. Help!

Thankyou. I was hoping it was an rpm limiter, causing my under rev due to the engine not reaching full temp. (Although moving it while the engine is running, did not make any difference to max rpm.)
"Back to the drawing board"
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Old 27-12-2019, 13:40   #56
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Re: Yanmar won't go beyond 2200 revs. Help!

Im fairly certain there is a governor (rpm limited) and it is susceptible to being fouled by gunk in the fuel. At least mine was. But it’s buried inside somewhere.

I think you are looking at sending it to an injector shop for service.
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Old 27-12-2019, 14:12   #57
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Re: Yanmar won't go beyond 2200 revs. Help!

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Originally Posted by Toccata View Post
Thankyou. I was hoping it was an rpm limiter, causing my under rev due to the engine not reaching full temp. (Although moving it while the engine is running, did not make any difference to max rpm.)
"Back to the drawing board"


How about the boost control valve on the injector pump, it increases the fuel proportionally to turbo boost and has a small hose from the intake manifold to the injection pump. The problem could be as simple as that hose being blocked, here's a pic of the device if your injector pump is this typeClick image for larger version

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Old 27-12-2019, 14:18   #58
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Re: Yanmar won't go beyond 2200 revs. Help!

Thankyou skipperpete.
I have read up about the cold start advance device, and also noted the BOOCON. Will check that pipe today. Now that would be nice if it is blocked....
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Old 27-02-2020, 17:15   #59
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Re: Yanmar won't go beyond 2200 revs. Help!

Fuel pump removed.
According to the overhaul shop the fuel flow regulator was faulty, fuel flow down %30.
The downstream damage was excessive wear as the fuel itself is the lubricant within the pump.
Back together. Installed. RPM right. Problem solved.
"It's always in the last place you look"
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