Yanmar YSM8 Leaking Fuel Injection Pump

[zackliscio]

Great news--we're back up and running, and the engine seems to still have good compression. Feeling very lucky to have stopped the runaway in time, and appreciative of this community for all the amazing advice.

When we were troubleshooting, we pulled both the lift and injector pumps. When running through the same steps again, we realized we no longer had fuel reaching the injector, despite having had it before. This made us realize we hadn't engaged the rod properly (wish I'd seen the reply below beforehand, but so it goes).

One thing that might have happened when removing the pump and replaced it is the possibility that you failed to engage the forked rod inside the engine which engages with the ball on the pump rack (item 13 in drawing in earlier post.

With the new lift pump and the lines properly bled, we're starting easily, compression seems healthy, and no apparent issues. I'll post updates if we find there's more to explore here, but otherwise hopefully getting out for a quarantine sail here in SF. Thanks so much all!

[Wotname]

Originally Posted by zackliscio

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With the new lift pump and the lines properly bled, we're starting easily, compression seems healthy, and no apparent issues. I'll post updates if we find there's more to explore here, but otherwise hopefully getting out for a quarantine sail here in SF. Thanks so much all!

Yes, great news - well done for sorting it out.

IMO, if the engine starts easily (and quickly) when cold, you have plenty of compression!

[zackliscio]

Thank you all so much, Wotname, billknny, SRQsailor, and Bilgediver. I was reflecting on how powerful this community is, and wanted to add a note for anyone who comes across this post in the future not to give up on your engine before you've tried fixing it.

In the course of this repair, we spoke to two Yanmar mechanics over the phone while sourcing parts, and both told us not to bother with the engine and offered to sell us a replacement instead. They both thought the engine was toast, and didn't give it a second thought. We described the same situation on this forum, and came away with actionable advice that actually led to a fix. It's incredible to have smart people working together to solve problems like this, and I'm very grateful for the CF community.

Happy sailing all!

[Bilgediver]

There is a wealth of knowledge in these forums many of the problems such as yours also crop up on other engines such as Volvo and Bukh so it happens frequently.
Glad to hear all fine.

Happy Sailing

[zackliscio]

Also wanted to share a quick link that was especially helpful on what not to do when troubleshooting the diesel. https://www.soundingsonline.com/boat...diesel-engines

[Compass790]

Originally Posted by zackliscio

Thank you all so much, Wotname, billknny, SRQsailor, and Bilgediver. I was reflecting on how powerful this community is, and wanted to add a note for anyone who comes across this post in the future not to give up on your engine before you've tried fixing it.

In the course of this repair, we spoke to two Yanmar mechanics over the phone while sourcing parts, and both told us not to bother with the engine and offered to sell us a replacement instead. They both thought the engine was toast, and didn't give it a second thought. We described the same situation on this forum, and came away with actionable advice that actually led to a fix. It's incredible to have smart people working together to solve problems like this, and I'm very grateful for the CF community.

Happy sailing all!

Your experience with the Yanmar mechanics is quite common for an old engine. In truth I cannot blame them as you can be opening a can of worms with a 1980 engine. The bill can easily rise to more than the cost of a good used replacement.
We have the same engine & whilst it is a noisy shakey beast it is well worth fixing if you cannot afford new.
I have rebuilt the injection pump & it's not too hard for someone with mechanical skills but I would have not touched it until I had done the lift pump as you were advised by Wotname.
Good that CF set you on the right path.