volvo penta tamd60c

[niftynev]

Does anyone know why my volvo becomes difficult to turn off after a good run?It sounds like one cylinder refuses to die. Had all the injectors out inspected and reset. Two marine mechanics have now walked away without any idea of fixing the problem.

[jimbunyard]

Leaky fuel shutoff solenoid? Just a guess and bump, DougR should have a better explanation and will likely be along later...

[DougR]

Checking and rebuilding the injectors is good for efficiency and optimum combustion, but it doesn't really have anything to do with your symptoms.

The TAMD 60c engine has a Bosch PE injection pump which has 6 inline high pressure fuel plunger pumps all geared to a common fuel rack controlled by the governor. When you turn the key to stop the engine you energize the mechanical stop solenoid (aft of the pump below the exhaust manifold) and the solenoid pulls on a linkage connected to a lever on the injection pump body. This action overrides the internal governor springs and pulls the fuel rack to the "no fuel" position. When the rack moves to its "no fuel" position it rotates all six of the high pressure plungers to their "no fuel" position and fuel delivery should stop, killing the engine.
What could possibly go wrong???? Well.....

- the solenoid could be weakening and not pulling the lever/rack all the way to the "no fuel" position. These solenoids are pretty strong and normally they pull the linkage with a real good "whack", but it's possible that the linkage is getting worn and needs some adjustment...that is, the solenoid is pulling correctly to the end of its normal travel but some slop/wear in the linkage is preventing the pump lever from moving as far as it should. The linkage has an adjusting screw on it to take care of this. You can also check this by moving the linkage by hand. With the engine idling, pull the linkage aft by hand and you should be able to move the linkage and stop the engine. If you can stop the engine cleanly by hand but the solenoid won't, then the linkage and solenoid need adjustment.

- The six high pressure fuel plungers inside the pump are all geared to the rack, and when the rack moves back and forth within the pump body it rotates all the plungers equally. This assures that all the plungers put out equal amounts of fuel for any given rack position and all the engine cylinders run at the same power setting. Likewise when the rack moves to "no fuel" all of the plungers should also go to "no fuel". But it's possible that a little wear has crept into the pump and perhaps one plunger isn't quite moving all the way to "no fuel". So one plunger isn't quite shutting off, and the engine kicks and bucks for a few turns before it stops running. Unfortunately adjusting this setting requires removing the pump and taking it to an injection pump shop. There they put the injection pump on a calibration stand and drive the pump with an electric motor while carefully measuring output from each plunger and setting them all equal. Kind of a pump tune-up. This can be a bit pricey and also requires the pump to be accurately timed when replaced on the engine.

Check out the stop solenoid linkage as your first step, and if that doesn't help you can call around to injection pump shops in your area for an idea of further costs.

DougR

[niftynev]

DougR, Thanks for the expansive explanation and remedy. Smooth seas mate!