Foton FT254 over-revving then no start

[rdbigfarmboy]

Runaway diesel engine. Been down that road way too many times on that subject lately. It is possible the fuel rack is stuck. It is possible the governor is damaged (there is no hard mechanical link between the governor and the fuel injection pump). It is possible you now have air in the fuel system. In the case of extreme overspeeding, you may have damaged the pistons, piston rods, crank bearings, valves, springs, and push rods. Check the simple things first.

I think I have read all the postings, I didnt understand all.
BUT
Its the linkage between the governor and the injector distributor pump(that thing that has lines going to each injector and distributes diesel). The linkage has stuck. make sure it will move. Its a simple sliding bar or rail. COULD POSSIBLY BE ONE OF THE SPINGS PUSH OR PULL IS OFF. This spring tension action is what acts on the sliding bar like thingy to feed more fuel under a load.
If it wont start not pumping fuel its stuck closed. If it run oft it stuck open.
You can fix it.

 

[FotonOwner]

RD,

I wish you had chipped in earlier.
All the advice I got was that you just can't do anything yourself and the IP has to come out.

Jim did suggest flushing out the governor, and perhaps if I did that a few more times who knows.

Anyway, the IP specialist said, once he pulled it apart, he would have disturbed anything that was stuck. He said there was a fair bit of rust in there, which may have caused some sticking.
It is now all back together and runs well.

The problem is, it is just so expensive to even have the IP assembly looked at, even without the cost to remove and re-install.
From what I was told it was possibly something to do with the governor weights being stuck; although, that was just a guess.

" - [The linkage has stuck. make sure it will move. Its a simple sliding bar or rail. COULD POSSIBLY BE ONE OF THE SPINGS PUSH OR PULL IS OFF. This spring tension action is what acts on the sliding bar like thingy to feed more fuel under a load.] - "

Not sure what you mean by the sliding bar, perhaps you mean you have to pull the governor end off to access. I tried operating the throttle lever back and forth but that had no effect. The throttle control and stop cable were both working fine.

Everyone said you can not remove the governor end of the IP without disturbing something. That still seems hard to believe as it has to be bolted together in the first place, and surely the governor just controls the flow of fuel so should not be too critical for timing.

I did find on the web someone reported an identical problem with one of these machines a few years back but there was no follow-up.

Although the tractor is now working well, and I have a better understanding of the system, it is less than satisfying that it cost me perhaps 1/10 of the cost of the tractor just to fix something that was not even broken, just stuck.

There has to be something else I could have done?

 

[Bob Rooks]

I am truly glad you have it all back together and running well.
I am also very glad you finally took my advice (post #34). :thumbsup:
Was there something else you could have done? I seriously doubt it. You ultimately did what you knew was best.

Farmboy: "the sliding bar like thingy" is called the fuel rack. Just so you know.

 

[Diamondpilot]

To me rust in there means either there was not sufficient oil in the injector pump or it set for a long time without running allowing the oil film to dry off and allow things to rust.

The best thing you can do for any machine is start it once a week and let it run for 10 minutes till up to temp then run it up and down the drive to lube things up.

Kind of like a 4x4 truck. Everyone has told me they require lots of maintenance, ect. I have had over 15 since 1986. I put them in 4 wheel drive once a week and drive it for about 1/2 mile through the field. Never had a single issue.

Chris

 

[doxford jim]

To me rust in there means either there was not sufficient oil in the injector pump or it set for a long time without running allowing the oil film to dry off and allow things to rust.


The rust part is derived from having water and oxygen in contact - ie moisture in the fuel over a period of time.

This should illustrate the importance of keeping diesel fuel tanks full when in storage. Also well worth considering is the installation of a coalescing fuel filter or water seperator to try and get the water out of the fuel before it gets to the fuel pumps !!!

So, keep moisture out of the fuel as much as possible - even Bob Rookes and I both agree on that :thumbsup::thumbsup:.

Also, adding a fuel conditioner would go a long way to helping with the prevention moisture buildup and contamination - help not cure.

So it looks as though this problem didn't just appear - the after effect did. I would suggest that the previous/original owner was/is not aware of the importance of good housekeeping where diesel fuel is concerned.

It is good to hear that you have the tractor back up and running.

Thanks for getting back to the forum with the eventual solution - I think we have all learned a little here.

Cheers

Jim

 

[ditech]

Hi Guys, just wanted to through my 2cents in on this subject. Diamondpilot & Jim D. could both be correct. A fuel injection pump is comprised of 2 seperate and distinct sections. The fuel lubricated section and the oil lubricated section.
Fuel section. The fuel first flows thru and lubes the transfer pump (small pump bolted to the side of the IP) and hand primer pump. Fuel is pumped by the transfer pump (under low pressure) to the fuel galley allong the top of the IP where it lubes the plungers & barrels. Fuel flows into the barrel and is pumped by the plunger (at extremely hi pressure) to the fuel nozzle (fuel injector) where it is atomized in the combustion chamber.
Oil section. When you add oil to the IP, the oil is actually going into a small sump that lubes the camshaft in the bottom of the IP that actuate the plungers (again the part that pumps the fuel under extremely hi pressure) the oil also lubes the governor components. Rust in either of the sections could cause the fuel rack to stick.
The govervor (gov) is fairly complicated and contains several springs, weights and linkages. When the operator pushes down on the throttle, he is actually just pushing on a spring inside the gov. This spring in turn pushes on "the linkage" that is connected to the fuel rack. When you crank & start the engine there are "fly weights" that spin inside the gov (the faster the engine turns the more force the fly weights create). These fly weights are also connected to "the linkage" and oppose the spring force applied by the operator. So in essence the operator is always trying to give the engine more throttle and the fly weights are always trying to take throttle away. The two forces balance each other out at a certain RPM. The mysterious "fuel rack" is simply a bar with gear teeth that is timed (dont confuse this with IP to engine timing) to each of the plungers & barrels. The fuel rack is connected to "the linkage" in the gov. So what ever RPM level the gov decides is needed the fuel rack is moved to that position and rotates the plungers & barrels to pump the appropriate amount of fuel to maintain that RPM.
An example; If the operator pushes the throttle all the way down and holds it there, the engine RPM will increase untill the fly weights counter act and balance that force. The engine will run at that RPM (rated engine speed) until either (1) the load on the engine increases which would cause the RPM to drop. This would make the fly weights slow down and lose some force, allowing the spring force applied by the operator to move the fuel rack to a more fuel position, causing engine RPM to increase to support the heavier engine load. Or (2) the load on the engine decreases causing the RPM to increase. This would make the fly weights spin faster creating more force and move the fuel rack to a less fuel position and in turn maintain the correct RPM. The gov is always trying to balance what the operator is asking for (RPM) and the load that is on the engine:ashamed:
Sorry, seems this turned into injection pumps 101 Hope is makes some sense.
Floyd--

 

[greg_g]

Sorry, seems this turned into injection pumps 101 Hope is makes some sense.

Very useful tutorial for beginners Floyd, thank you. Hopefully it will serve to reinforce earlier advice; specifically that Chinese tractor novices have no business trying to service the fuel delivery assembly themselves. And that the OP did the correct thing in calling in qualified assistance. To the uninitiated, it may have seemed an expensive solution. But I'm confident that - after investigative and/or irreversible tinkering - it would have cost a lot more to replace it

//greg//

 

[Bob Rooks]

Very good Floyd, well done. :thumbsup:
But you left out one item in the timing section (probably just an oversight) which has to do with rotating the barrels so the scrolls and helix are positioned within spec., and the shimming of plungers to get the correct lift from the cam. This can only be accomplished, with any accuracy, on a Bacharach (or similar) calibration and test bench. Diesel fuel systems are not total rocket science, but requires an above average degree of technical knowledge and understanding. Hence the reluctance to provide individual parts in the retail marketplace, and amatures are highly less likely to follow safetey protocols. It's kinda like motorcycle wheel spoke tightening - some things are best left to an expert, and I am in total agreement with Greg's post.

 

[ditech]

Chinese tractors are meant to be end user servicable. Unfortunatly the fuel injection pump is one area that doesn't lend itself well to be tinkered with or repaired in the field. As Bob R mentioned, a fuel test bench (bacharach test stand) should be used anytime internal repairs or adjustments have been made to the IP. The IP's used on diesel engines (usually) are capable of supplying a lot more fuel and allowing much higher RPM than the engines they are mounted on can tolerate. That being said, a well meaning but uninformed adjustment could easily allow the engine to reach an RPM that could do serious damage (BOOM!) before the operator realized it. The IP also is capable of injecting alot more fuel and creating a horse power level that the engine isn't capable of sustaining.......again........BOOM! This just isn't a place to "give that screw a turn and see what happens"........again......BOOM!
Obvoiusly, these engines are designed to operate within certain Horse Power/RPM range with a reasonable safety margin. I don't know how much safety margin is designed into these engine before damage occurs.
The calibration and adjustment of the IP is a very precise process and unfortuantly expensive. But probably best left to a fuel injection shop. Very few diesel repair shops work on IP's they only remove them and:thumbsup: send them to a specialty fuel injection shop. When repaired/calibrated they will then reinstall and time them to the engine (something you can do in the field) I agree with Greg, Bob and others that internal repairs/adjustments of the IP are outside of normal "nut and bolt" mechanical tasks.
Floyd--:thumbsup:

 

[greg_g]

internal repairs/adjustments of the IP are outside of normal "nut and bolt" mechanical tasks.

Same advice applies to Chinese fuel injectors

//greg//