qd32 engine run off

[coolbigrock]

hello to all,can one shed any light on this problem,qd32 gives a run off after turning off the engine,i have taken off the intake pipe and used my hand to cut the air being drawn by the engine,with this action the engine shuts down smoothly,fuel cut solenoid is a pain to get to,thinking that it might not be seating properly.

 

[Old.Tony]

Watch the PCV as well. If you're getting excessive blowby (worse if it's combined with an overfull sump) you might be experiencing diesel runaway.

There are only three things you can do if the engine starts to runaway.

1) Stand back and watch it self-destruct and make sure you get some good video of it

2) Block the air intake as you've done, be careful because if the RPM are too high it will remove skin

3) Remove the PCV hose from the air intake.

What happens if you clamp the fuel line? If it shuts down nicely, then for some reason the shutoff valve isn't closing and needs replacing.

If clamping the fuel line doesn't work but removing the PCV does, consider honing the cylinders and going a size up in piston rings (not a small job).

 

[coolbigrock]

will checked the oil level tomorrow,it only occurs went i am turning off the engine,it runs fine other then that,will clamp the hose and see what happens,thinking the shut off valve as well,yes i know honing would be a big job,thanks for the info.

 

[happy john]

More than likely the cut off solenoid is not getting 12 volt or has a intermittent earth issue.

 

[tweak'e]

either fuel cut is stuck open (rare?), its running on oil or an injector is leaking.
has any work done on the fuel pump recently? some guys find some engines will run on due to the timing being advanced.

 

[happy john]

I thought that as well Tweak'e, it sounds like it's just not shutting down rather than run on as we all know. I did have that voltage problem on my TD27 25 years ago I think they are near identical to the QD32, not sure if that model has a crank angle sensor but that can cause that type of issue also.

 

[tweak'e]

normally run on is rough, probably blow smoke as well.
if its idling smooth but just won't turn off i'm picking shut off valve.
not electrical because they are off with no voltage......actually just a mad thought put a meter on the lead or even a small light. just make sure power is turning off when you turn the key off.
in case you have something back feeding the circuit or a relay thats welded on.