Some wvo by products have turned into a glue type substance when the engine sat. It may take a few days of sitting with some laquer thinner to loosen up all the gunk.

Leave the injector lines off. Pump the laquer thinner in with your finger pump and let is sit. Chemical action is slow to non existant at low temperatures so get the injection pump warmed up to room type temperature.

Turn the engine over and watch for some squirting from all the ports. When it occurs then pump clean diesel into the injection pump with the relief valve removed so the junk and thinner can leave the pump better. You may get globs of stuff.

If the fouth port is still not producing give it a little tap then. Rotate the engine. If still not working let the soaking continue for a few more days. The laquer thinner should dissolve all the junk.

The small piston in the bore is a really precision fit so it takes a solvent some time to get into the thin space and at the sticky stuff. Laquer thinner is a good solvent for animal fats and a lot of other things but not aggresive towards metals.

You do not want to leave that stuff in the injection pump anyways. The diesel fuel is not really a solvent for it. But a good soaking flush can be cheap and effective.

The stuff in a can is too weak in concentration to get the congealed fats dissolved etc for sure. I am not even sure if it is designed to tackle what you probably have. The soaking period is the secret with the laquer thinner as it breaks down the undesirable stuff. What you eventually do is pump all the junk and laquer thinner combined out through the relief valve with fresh diesel rather than feed all the trash through your injectors. Should work out okay. Now if the wvo had water in it I am not so sure as there may be some damage. At present I go with the glue probability though. This soaking is easy and cheap to do.

Personally I would remove the relief valve as it makes pumping in the solvent and pumping it and the junk out easier. If you do give it a soak in the laquer thinner as well. Also remember that the laquer thinner is seriously flammable. Probably about ten dollars a quart.