I have a 1996 yanmar 3gm. Races out of control. Sent fuel pump to be cleaned, changed out governor, checked linkage, at wits end.. What would cause this engine to race at high speed so I have to shut down with fuel cut off before it explodes? Please help me. Shelby Scott
Racing on 3gm yanmar diesel
- Thread starter shelby scott
- Start date
Can you be more specific? Is this when it starts, only when you rev the engine up, what happens if you pull back on the throttle, does the throttle have any control at all?
Brian
Brian
Have you checked that you have not over filled the oil in the crankcase? If it's be accidentally over filled remove enough to bring it to the just fill level.
Also check the throttle linkage to make sure you haven't bent something...
Then go to the expensive stuff.
Also check the throttle linkage to make sure you haven't bent something...
Then go to the expensive stuff.
bad rings, or valve seals can allow oil to be leaked into the engine. Resulting in a runaway or surging etc.
Racing yanmar
The throttle has no impact. Races from first of start till emergency kill..
Yes I pulled it twice and used mirror and light to verify the pin was in the crotch of the "y". Good thought any more ideas.....please???
It has less than 200 hours on the engine. And this problem started after the boat has sat for a couple years unused...
Thank you I have emptied and changed all fluids and new filters and tried to run engine without linkage attached. No difference, still races and scares the bejesus out of me.. What's next. Thanks for the help. More good ideas? Please, and thanks to all my sailing friends for useful suggestions I really do appreciate your help
If the engine shuts down with the fuel stop lever them it is unlikely the problem is engine oil leaking into the combustion chamber.
Try disconnecting the throttle linkage at the engine and see what you learn from running the engine and trying to control the throttle at the engine. It may be that the cable is seized. Or perhaps some connection between the throttle and governor is not working. ???
Try disconnecting the throttle linkage at the engine and see what you learn from running the engine and trying to control the throttle at the engine. It may be that the cable is seized. Or perhaps some connection between the throttle and governor is not working. ???
I tried running without throttle cable attached no difference then pulled timing gear case and replaced governor reassembled and no change races from start and scares the bejesus out of me ...(all springs and internal linkages seems to be in excellent shape)???? Now what?
To be clear, you moved the throttle lever to both ends of its travel?
The problem has to be in the control of the fuel flow. Somehow the fuel valve in the injector pump is not being adjusted.
The problem has to be in the control of the fuel flow. Somehow the fuel valve in the injector pump is not being adjusted.
I appreciate your reasoning and help. That is why I took the injector pump to Thompson diesel here in Tulsa, they changed out o rings? And repaired pump. And it still races all out. I am ready to sacrifice a tool to Neptune (no virgins around) got any ideas?
I can only say to take it back to them. Somehow too much fuel is getting thru.
My understanding is that adjusting the throttle lever adjusts the tension on the governor which in turn adjusts the fuel valve in the injector pump. If changing the position of the fuel valve in the injector pump is not changing the flow of fuel then there must be a leak past the valve.
Good luck,
Ken
My understanding is that adjusting the throttle lever adjusts the tension on the governor which in turn adjusts the fuel valve in the injector pump. If changing the position of the fuel valve in the injector pump is not changing the flow of fuel then there must be a leak past the valve.
Good luck,
Ken
Good idea from Ken. I think your pump was reassembled incorrectly. It is possible to install the plunger or plunger assembly in a rotated position. Pre-set to wide open throttle as it were. Its been a long time, but I think when I was in a "how does this work" mood after chasing down a fuel leak at the high pressure connection to #3 injector delivery valve, the same thing happened to me. The engine ran wide open and made so much black smoke it filled the harbor in about 10 seconds. I was able to accomplish this by pulling the guts out of the injector plunger even without removing the pump. When I put it back in, it was rotated 180 degrees. Luckily I turned it around and the engine worked fine again.
Allan
You guys are awesome. And good detectives. I know it did it a few years ago then the owner died and I ended up with it. It raced before I did work on it and it races now... So I am going to go take the injector pump out and back to the diesel shop. To humbly ask if the inadvertently put the plunger in backwards... I will check the fuel return line. Thank you all!,, ! A good fraternity of sailors.
Well i hope its as simple as that. Maybe the prior owner had work done and they got it wrong, then your guys just reassembled it the same way. It looks like the drawing indicates, with full fuel cut off, the vertical groove in the spiral cutout should face away from the low pressure feed inlet side. Too bad you have to pull the pump to have it verified. Does the rebuild shop make house calls?
I needed that laugh, house calls...
I have to admit they have been patient and helpful to me, seems like a group of quality guys, (we all cna make mistakes) I now am having to call upon all reserves to be persistent and not feel defeated.. so thanks,