Jinma 284 Fuel Pump Issue

[TheSheriff]

Been awhile.
I'm still researching but I thought I would post here just in case someone has seen my specific combination of symptoms and what the fix turned out to be. I'm leaning toward injectors or governor? but not yet sure how I'd proceed with either.

History. 2010 Jinma 284, 450ish hours. Used regularly, but due to health issues, only used 5-6 times for very short periods last 2-years. Maintained fresh diesel with conditioner. I had not used it for last 4-5 months due to flat rear tire. Should have turned off the fuel but didn't. No history of engine oil or pump oil use, nor either "Climbing" the dipstick.

So I needed to back out of the carport to remove the box blade to more easily jack up the rear. Pulled the dipstick on the F-pump and and a very thin liquid (Diesel I assume) poured from the hole; perhaps an ounce. Much thinner than the compressor oil I have always used. Drained and refilled.

Started tractor, it blew a bit of smoke and immediately over-revved. Pulled the kill cable. Repeat several times. Throttle cables/arms appear to be moving fully and normally. Lubed with WD. Started again and manipulated the kill cable to maintain safe RPM. After running perhaps 5-6 minutes and jockeying the throttle (Via the kill cable) it idled normally. Backed it out and left it running while I disconnected the BB. After running 15-minutes, it went the opposite direction and idle dropped too low and stalled. It ran fine and would not stall while driving, just didn't want to idle. It would also re-start just fine, then again run fine, but stall if left at normal idle.

Hoping I had broke something free, I started it next day. The same exact thing. Over-revved, manipulate, warm up, idle normally and then runs great but wants to stall on idle. Thought I would try once more the next day. Same exact thing EXCEPT it never went to normal idle after warm up. Whatever was "breaking free" before was no longer. Tried again, same thing.

Any ideas appreciated.

 

[piper184]

my guess is that the weights or mechanism in the governor are stuck, or at least some of them are. Hopefully they aren't stuck with rust.
Here is what I would try. Drain the pump completely and refill with something to dissolve any gums that might have built up for dried oil. Diesel fuel would probably work best. Put a cap on the overflow nipple and fill it to the brim of the breather hole.
Let that sit for a day or two. Then drain thoroughly and refill with engine oil (this is fine for normal use too) just until it runs out the overflow nipple.

If that does not do the trick, I think you can safely remove the cover from the governor end so that you can have a look inside for gum or rust. Hopefully you won't have to do any more than that. Otherwise you might have to pull the pump and have it worked on at a good diesel shop, but that becomes a pain and expensive.

My 2007 284 leaks a little fuel into the governor sump. I put a short piece of clear plastic hose on the overflow nipple and plugged the end. That way I can monitor anything that comes out and drain off the excess. When I check the engine oil before startup I check overflow. Once I have had to drain it a few times, I just drain and refill. It usually goes until I am close to needing an engine oil change anyway. I've been operating that way for years and hundreds of hours. Seems to be just fine.

 

[TheSheriff]

my guess is that the weights or mechanism in the governor are stuck, or at least some of them are. Hopefully they aren't stuck with rust.
Here is what I would try. Drain the pump completely and refill with something to dissolve any gums that might have built up for dried oil. Diesel fuel would probably work best. Put a cap on the overflow nipple and fill it to the brim of the breather hole.
Let that sit for a day or two. Then drain thoroughly and refill with engine oil (this is fine for normal use too) just until it runs out the overflow nipple.

If that does not do the trick, I think you can safely remove the cover from the governor end so that you can have a look inside for gum or rust. Hopefully you won't have to do any more than that. Otherwise you might have to pull the pump and have it worked on at a good diesel shop, but that becomes a pain and expensive.

My 2007 284 leaks a little fuel into the governor sump. I put a short piece of clear plastic hose on the overflow nipple and plugged the end. That way I can monitor anything that comes out and drain off the excess. When I check the engine oil before startup I check overflow. Once I have had to drain it a few times, I just drain and refill. It usually goes until I am close to needing an engine oil change anyway. I've been operating that way for years and hundreds of hours. Seems to be just fine.

Thanks for the reply, that sounds like a good first step. I'm not having much luck finding a diagram of the pump internals online. Would I be correct that the governor end is the rear most housing where the oil fill and dipstick is located?

 

[piper184]

Yup the back end.
Go to my web site at harnerfarm.net and click on the Jinma link. There you will see 4 files. Open the top file and go to page 40 for some pictures.

 

[TheSheriff]

Yup the back end.
Go to my web site at harnerfarm.net and click on the Jinma link. There you will see 4 files. Open the top file and go to page 40 for some pictures.

Thank you. It's been so long since I had to reference it, I forgot I had that manual stuffed in a file cabinet. Sorry for your recent loss.

 

[TheSheriff]

After a 3-day diesel soak, no change in the over-rev issue.

I did come across this thread https://www.tractorbynet.com/forums/threads/jinma-254-starting-problem.147429/ and noticed he also had a over-rev, though the main issue seems to be it not starting again afterward. I noticed the mention of a possible stuck piston and disc's. Unfortunately there was no resolution mentioned.

I plan to start removing the governor housing in a few days, but I wonder if a stuck piston/disc(?) could also fit my symptoms, or does the fact my tractor has no trouble starting, eliminate this as a possible cause? I only ask b/c removing that plate under the hard lines (As mentioned in that thread) looks to be much easier than the Gov housing if they are both just as likely to be the cause.

 

[piper184]

I have never been inside the governor housing so this is just a guess.
It sounds like the fuel rack is stuck and the governor can not produce enough force to get it to move. I think the fuel cut off is a separate device and that is working so that you can stop the engine and then restart it. But the rack is stuck in the wide open throttle position.
I think Bob Rooks said one time that these pumps are a clone of the ones made by Bosch. You might try searching for an exploded diagram of a Bosch pump to get an idea of what you are dealing with.
Sorry I can't be of more help than that. Best of luck and please post what the final solution is. Also take lots of pictures as you go!