Foton FT254 over-revving then no start

[FotonOwner]

Started the FT254 to work on the PTO clutch issue and it immediately started to rev very fast. As soon as I could think clear enough I pulled the stop button and shut it down.
Couldn't get it started again. The fuel was near the red but not dangerously low, tried topping up the fuel and bleeding off any air, but seemed fine.

Cranks over fast but not even a cough - doesn't sound like I have full compression.
The decompression lever appears to operate normally.

Any ideas?

 

[greg_g]

Usually one would follow the stop engine cable all the way to the stop lever on the injection pump assembly. That lever might be stuck in the KILL position. But you wrote "stop button". I'm not sure what that means.

//greg//

 

[FotonOwner]

Usually one would follow the stop engine cable all the way to the stop lever on the injection pump assembly. That lever might be stuck in the KILL position. But you wrote "stop button". I'm not sure what that means.

//greg//

Thanks Greg,
Sorry for not being clear. Yes, it is a redish pull knob that goes via a cable, as you say, to the governor. I have looked at it and it seems okay, plenty of spring tension and goes back into place.

 

[greg_g]

Ok. Did you also use decompression to stop the engine? or just cut the fuel? Because it seems rather coincidental that you'd suspect a possible compression issue as well.

//greg//

 

[Bob Rooks]

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.

 

[FotonOwner]

Ok. Did you also use decompression to stop the engine? or just cut the fuel? Because it seems rather coincidental that you'd suspect a possible compression issue as well.

//greg//

Greg,
No I just pulled the stop knob, I don't think it ran for more than a few seconds.
I suspect compression as it seems to crank much faster than normal like the compression was held off. I checked the compression lever and all seems fine.

 

[Rich Waugh]

Sounds like you'll need to pull the valve cover and check out the compression release and all the valve action.

 

[greg_g]

Ok, but just so there's no misunderstanding;
1. you cranked the starter
2. the engine seemed to spin too fast (like the compression release was open)
3. the engine started
4. the engine over-rev'd
5. you quickly shut it down with the stop cable.

If yes, #2 could have been an anomoly. I wouldn't worry about it unless/until you can reproduce that specific symptom. If no, please help me understand what I'm missing. It's important whether to consider or to ignore this particular symptom before proceeding.

//greg//

 

[Brad_Blazer]

Started the FT254 to work on the PTO clutch issue and it immediately started to rev very fast. As soon as I could think clear enough I pulled the stop button and shut it down.
Couldn't get it started again. The fuel was near the red but not dangerously low, tried topping up the fuel and bleeding off any air, but seemed fine.

Cranks over fast but not even a cough - doesn't sound like I have full compression.
The decompression lever appears to operate normally.

Sounds like Greg's list occurred in the sequence of 3,4,5,1,2. The fast starter spin occured after the running overspeed episode.

 

[Bob Rooks]

I'm with Rich. Time to pop the valve cover.:thumbsup:
I'd look for bent (stuck) valve stems since the valves probably floated during the overspeed.

I don't think it ran for more than a few seconds.

It doesn't even take that long to float the valves and do major damage.
Hopefully you dodged a bullet.