Foton FT254 over-revving then no start

[FotonOwner]

"tried topping up the fuel and bleeding off any air"

Are you sure fuel is present at the injectors?

Is there any chance the turning over faster is simply due to a warmer temperature?

Could be, the weather is warming up - will be rather hot one today 35C and hotter tomorrow over 100 in the old money.

Didn't check the fuel at the injectors only at the bleed points on the filter and injector pump.

 

[doxford jim]

Hi,

I would be inclined to look at the fuel injection pump area - you said it started to "overspeed" and then hit the stop !!!

If it started to overspeed while working running the engine in a normal fashion, indicates there could be a problem with the governor attached to the fuel pump. My guess is the governor is sticking and not operating properly - maybe very stiff. That could cause the mechanism to not "reset" - so what you might have is the governor actually cutting off the fuel even when stopped. How many hours on the tractor ??

I would try to clean up the inside using something klike diesel fuel to wash out the inside - just in case. Flushing out the governor after running for a short time with diesel, a couple of times certainly won't do any harm and won't cost very much.

Reason I say this is if the governor is still in the "fuel stop" position, your fuel pump plungers will be just sending fuel past the barrels via the pump helix.That is there will be no fuel pumped is what I am trying to say.

Hope this helps.

Cheers.

Jim

 

[FotonOwner]

Thanks Jim,

I have done about 100 hours on the tractor. It has been working fine. It was running well when I parked it in the shed, and when I started it again, it just started to roar so I shut it down.
Have no idea what is inside the the governor, I guess removing it and giving a good flush couldn't do any harm.
Have you pulled these off before and is there any precautions, or hints, in doing so? I notice the two lock wired pre-sets which I wouldn't touch.

 

[doxford jim]

Thanks Jim,

I have done about 100 hours on the tractor. It has been working fine. It was running well when I parked it in the shed, and when I started it again, it just started to roar so I shut it down.
Have no idea what is inside the the governor, I guess removing it and giving a good flush couldn't do any harm.
Have you pulled these off before and is there any precautions, or hints, in doing so? I notice the two lock wired pre-sets which I wouldn't touch.

I am assuming that the fuel pump is the inline CAV type pump that seems to be common on the Chinese tractors.

There should be a drain plug fitted underneath the bottom of the fuel pump - to drain out the old lubricating oil. You refill the lube oil with new, by putting it through the vent cover hole - where the vent cover screws in. The governor is attached to the injection pump and it is all lubricated by the same oil.


First, try moving the fuel shut off rack on the injection pump - it should move easily, back and forth, pushing it with your fingers or by hand. If this is free try moving it to the mid throttle position - sometimes these pumps will need a bit of throttle to admit fuel and often midway of total travel is a good place to start. Having it at the extremes often causes either very high speed or stop (shuts fuel off completely). If the fuel adjustment rack moves readily - go ahead and drainout the old lubricating oil in the injection pump housing.

Drain out the old lube oil into a suitablee container if possible and note it's condition - any signs of water (= internal rust) or metal bits (mechanical failure) etc. Refill to the level of the dipstick mark with diesel (will clean and does lubricate as well). Try starting the tractor and if it starts run it for four or five mintes - working the fuel regulating slightly (hand or foot throttle) to ensure freedom of movement and proper operation. Stop the engine is the usual manner - redrain and refill as before - be sure to check oil that has been drained to see if there is any indication of contamination etc. Repeat two or three times. When finished for the final fill use recommended oil. Some use engine oil 15W40, others use compressor oil and universal tractor fluid has been mentioned of winter conditions - thin enough to lubricate in severe cold when other oil is very thick and viscous.

Hopefully that might be your problem.

If that doesn't work then I think there might be a problem with the injection pump and it may need further attention.

As with all things, I would try the simple stuff first - check the injection pump oil. If there is no oil (lost) that could be your problem - you won't know until you look. A good internal flushing costs only a bit of your time - the amount of oil/diesel needed is just a couple of ounces.

Please let us know how you make out. There are others that will readily chip in with their experiences - so don't be shy in asking.

Good luck

HTH

Jim

 

[FotonOwner]

Drained and flushed the governor as suggested, there wasn't a lot of dirt in in oil.
The locking wires on the stop screws was broken but no indication that the settings were grossly out.

Replaced the wire but don't think that was a factor.

Loosened the air bleed screw on the injector pump and checked that fuel was expelled with the hand pump, then cranked the engine and confirmed that fuel was expelled from cranking.

There are two screws in the injector pump and the book suggests loosening both but only one had a ring for finger operation.

Is the fuel at this point at the input or output side of the injector pump? Is there one screw at each side?

If fuel is exiting this bleed point, does that mean the injector pump is operating, or is that just pressure from the fuel pump? Is it necessary to check injection pump operation at one of the plugs? Would you just slacken off the fuel line nut?

 

[greg_g]

If somebody or something turned the nut under that "loose wire", there's definitely a chance that it's a factor. It's a security wire to discourage tampering - like those wire seals that the utility company puts on your electric meter. But that's just speculation for now.

There is a high pressure and a low pressure side to the fuel delivery system. Fuel under low pressure travels through rubber hoses, and that ring is on the low pressure side. So is the hand primer pump, which moves fuel only as far as the injection pump itself. That means tank>lift pump>fuel filter>injection pump. That ring vents the low pressure side permitting you to confirm that fuel is in fact getting as far as the input to the high pressure side.

The high pressure side consists of the IP itself, the hardlines, and the injectors. You must crank the engine to move fuel through the HP side. So bleeding the system consists of using the ring and hand primer, followed by loosening the hex collars at the injectors and cranking the engine. When bubbles stop and raw fuel flows, tighten the collars. You've just bled the fuel system. If you don't get fuel at the top, you've likely got an IP problem.

But this is actually the opposite of what usually causes a runaway diesel, what we interpret you to mean by "over-revving". That's caused by a stuck IP that's sending too much fuel to the injectors. Of course, I suppose there's the wierd chance that the thing could have stuck briefly - right before it failed. Sorta like a 2-stroke engine revs up right before it runs outa fuel. But given the information at hand, it's simply too hard to be sure from so far away.

Bleed the fuel system again, this time using the sequence I described above. See what happens.

//greg//

 

[doxford jim]

Don't forget to put the fuel rack in mid position to ensure that the pump will be delivery fuel. If this nut was lose, then how do you know the fuel rack is positioned topump fuel ????? If the rack is shut off completely - ie at the extreme end, then NO FUEL WILL BE PUMPED IF THE ADJUSTMENT IS OUT OF WACK - sorry about the large case letters, but this is important.

Make sure there is delivery stroke on the fuel rack - easil done by moving the rack to mid position. Once this is determined, then try to start the tractor or at least see if the injector pump pumps fuel. This is easily proved by lossening a fuel line where it is attached to the injector. If id weeps fuel when you trun the engine on the starter, then chances are, when the connection is tightened and the statter used again, the tractor will start.

Go back through your checks and confirm your situation - then report back. There are a lot of knowledgeable people here, so don't be hesitant of asking - but you have gotta check for yourself.

Cheers

Jim

 

[Bob Rooks]

No apologies for large case letters here. WHENEVER WORK IS PERFORMED ON A GOVERNOR OR FUEL INJECTION PUMP ASSEMBLY, AND PRIOR TO STARTING THE ENGINE, DISCONNECT THE AIR CLEANER FROM THE INTAKE MANIFOLD AND HAVE A ROUND PIECE OF 3/8" THICK (MINIMUM) PLYWOOD AT THE READY TO COVER THE INTAKE IN CASE OF A RUNAWAY. Why? Because it DOES happen. And don't think for a second that shutting off the fuel will stop it in time.
Ignorance is truly bliss.

 

[FotonOwner]

[ - If somebody or something turned the nut under that "loose wire", there's definitely a chance that it's a factor.- ]

Yes, it is a concern that it has been tampered with, I just didn't think it would cause a runaway when it has been working well beforehand, and I didn't see signs of recent change. Of course it could be that it had played up previously and that is why it was messed with.

[ - The high pressure side consists of the IP itself, the hardlines, and the injectors. You must crank the engine to move fuel through the HP side. So bleeding the system consists of using the ring and hand primer, followed by loosening the hex collars at the injectors and cranking the engine. When bubbles stop and raw fuel flows, tighten the collars. You've just bled the fuel system. If you don't get fuel at the top, you've likely got an IP problem. - ]

Good I will give that a try, (that spanner size wasn't in my kit, may be 20+ mm). Not looking at the runaway at the moment I am just trying to get it to fire again, and worry about the over-revving once it starts.


[ - Don't forget to put the fuel rack in mid position to ensure that the pump will be delivery fuel. If this nut was lose, then how do you know the fuel rack is positioned to pump fuel ? If the rack is shut off completely - ie at the extreme end, then NO FUEL WILL BE PUMPED IF THE ADJUSTMENT IS OUT OF WACK - sorry about the large case letters, but this is important. - ]

I guess I am thinking that I can loosen off the hex clamp, as Greg says, and crank the engine. If I get fuel pumping out then that should tell me the injector pump is operating. If not then I can move the throttle lever and try again, which, I think is what you are saying. I feel reluctant to crank it with the throttle opened up, at least at first.

[ - DISCONNECT THE AIR CLEANER FROM THE INTAKE MANIFOLD AND HAVE A ROUND PIECE OF 3/8" THICK (MINIMUM) PLYWOOD AT THE READY TO COVER THE INTAKE IN CASE OF A RUNAWAY. - ]

Yes I saw this issue while searching on runaway engines, where some did not respond to the governor shutoff.

 

[FotonOwner]

Found the 21 mm open-ender in the Foton Toolbox. Undid one of the lines and didn't see a drop of fuel when cranking. Set the throttle to half way, and still nothing.

So now what?

I guess it could be a faulty governor is cutting fuel to the injector pump.
Perhaps it first failed somehow and didn't restrict the fuel, then after stopping it now blocks the fuel. Or could be the IP failed, but that would need two separate failures.
I think more likely the governor.

I see two hex screws, one on the sides of the governor that look like they hold the two halves together. (heads facing away from the IP) Seems a bit odd there would be only two screws. Has anyone pulled one of these apart?