injection pump assembly

splax

.
Nov 12, 2012
692
Hunter 34 Portsmouth
I have decided that the issue with my 3GM30F is that a weight on the governor has broken off the shaft so I am to remove the injection pump assembly and send it off for repair. Anyone else done something similar?
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Indeed.. The governor is very robust.. It would be an unusual failure to have a weight come loose from the collar assembly.. not saying that your diagnosis is not correct.. usually governor problems are the result of something upsetting the delicate balance of the little springs or a bad o-ring on a shaft causing too much "stick-tion" Sounds like the gear case cover has to come off regardless..
 

splax

.
Nov 12, 2012
692
Hunter 34 Portsmouth
Given the chorus of counter argument, I have come instead to the determination that the injector pump should be replaced. Thank you for your input.
Reasons the Woodward governor probably not at fault : the engine runs very well, there is very little information on the process of repairing or replacing it, and the noise I was hearing at high RPMs is probably an alternator bearing. So my belief I had broken whatever was causing the noise and therefore the engine was not getting fuel is probably wrong.
It is a fuel supply issue. I thought maybe the injectors needed refurbishment, but the injectors do not exhibit symptoms of fouling and the engine has lots of power. I have been using Seafoam in the fuel since 2012, performed the hot soak yesterday, even though there was a slight improvement in the engine power the RPMs did not go above 2900.
The injector pump has a fabric diaphragm that wears, so is a likely culprit.
Please weigh in if you have experience or information on the injector pump replacement.
 
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
The process is described in the shop manual. The pump can be tested and repaired by any diesel shop. There is a side cover to access the pump fuel rack which engages in a forked lever that moves via the governor mechanism. The rack needs to be positioned so the pin on the rack goes out the top of the cover through a slot. If this is not positioned to go through the slot you will bend the rack and needless repair will follow. In other words - if the pump does not come straight up and out easy then do not force the issue until you are very sure nothing is interfering.

There are shims between the pump body and the cover so keep track of them - extras are available from Yanmar. These might be a bit stuck to the pump or the cover or both with RTV sealant. When you reinstall you need to time the injector pump pulse. Less shims earlier injection, more shims later injection. You should use a drip tube or similar to verify pump timing and the starter needs to be off so you can see the timing marks.

You also need to be certain the rack is engaged in the governor fork lever else you could have a runaway.

By the way - before you have to learn all this stuff - why do you think the pump needs service? If it is solely RPM then verify your exhaust elbow is not strangling the exhaust flow, that the valve lash is set perfect, and that you do not have any fuel supply restriction anywhere between the end of the tank pickup tube and the guard filter.

Charles
 
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splax

.
Nov 12, 2012
692
Hunter 34 Portsmouth
Mr. Erwin,
Thank you for your reply. I eliminated the exhaust elbow as the culprit a couple years ago by soaking in muriatic acid, but was thinking about a fuel restriction possibility this morning. I plan to go to the boat tomorrow afternoon to test the theory and will confirm results afterward.
 
Jun 2, 2011
347
Hunter H33 Port Credit Harbour, ON.
Given the chorus of counter argument, I have come instead to the determination that the injector pump should be replaced. Thank you for your input.
Reasons the Woodward governor probably not at fault : the engine runs very well, there is very little information on the process of repairing or replacing it, and the noise I was hearing at high RPMs is probably an alternator bearing. So my belief I had broken whatever was causing the noise and therefore the engine was not getting fuel is probably wrong.
It is a fuel supply issue. I thought maybe the injectors needed refurbishment, but the injectors do not exhibit symptoms of fouling and the engine has lots of power. I have been using Seafoam in the fuel since 2012, performed the hot soak yesterday, even though there was a slight improvement in the engine power the RPMs did not go above 2900.
The injector pump has a fabric diaphragm that wears, so is a likely culprit.
Please weigh in if you have experience or information on the injector pump replacement.
The injection pump is the high pressure pump that delivers the fuel pressure to the injectors. I believe that you are referencing the transfer pump. The transfer pump has a leaver that runs on a cam lobe and the leaver pulls down on the center of the diaphragm. The external leaver does the same thing. Sometimes there can be wear in the lever mechanism which could restrict the movement of the diaphragm. There are also 2 check valve in the pump. If the diaphragm breaks fuel could leak into the engine crankcase. Usually the check valves either work or they don't. If they don't the transfer pump will not move any fuel. The pump is most likely not serviceable so if it is defective it is replaced complete. If you remove the line from the exit (pressure side) and crank the engine you will be able to tell if the pump is good or not. If there is a lot of fuel flowing then the transfer pump is most likely still good. If there is only a small dribble, with unrestricted feed, there is a possibility that it is defective. The transfer pump should also be able to deliver a small amount of pressure if you block the discharge when the engine is cranking. It is usually 2 or 4 bolts and a gasket holding the transfer pump in place.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
P1030176.JPG Yup, a few of us H-34 folks have changed our "lift" pumps.. That is what it is called in the shop manual.. a low pressure pump that "lifts" the fuel from the tank and feeds it to the high pressure injection pump.. It is held in by two bolts .. it has banjo connections on it so get some new copper washers before starting to change it.. Access to it is terrible .. ya end up with one hand from the front of the engine box and the other hand through the access hole for the secondary filter.. Attached picture shows the filter housing.. the pump is to the left of that.. you can see the outlet fitting and hose to the filter.. Before changing, get a 90 degree screw driver and tighten the top lid screws (without stripping them) .. you could have a very small air leak anywhere from the tank to the suction side of the lift pump.. or you could have some trash obstructing the in-tank tip of the fuel pick-up tube..
 

splax

.
Nov 12, 2012
692
Hunter 34 Portsmouth
Monday I removed a squeeze bulb I had installed in-line to assist with filter changes with no improvement. I replaced the lift pump a couple years ago since the old one was leaking fuel into the bilge. I will be looking for an air leak, but think trash at the intake is likely.