Yanmar YSM 12 starting issue

[hapibeli]

Our 1981 Yanmar YSM 12 was hauled out of the boat last June, gone through by our mechanic (50 years of experience), cleaned out with muratic acid as the head had never been off and the water jacket was loaded with salt residue. Everything checked out on the bench.
We got her back onboard, all hooked up, begin trying to get her started and after many attempts and searching for the issue, we finally added an electric fuel pump in line with the second filter, which then would go into the fuel lift pump. She started after 3 or 4 cranks, and ran like a dream. High fives as it were between mechanic and me.
Next day, I went to start her, and lots of motor turning over, but no catching. She tried a couple of times, but no go.
When the key is on, the pump pushes fuel through to the high pressure pump, but nothing.
Does anyone have any ideas? Batteries strong, alternator and starter work fine.

[unclemack]

Not knowing what work your mechanic carried out makes it difficult to offer much advice except it's usually fuel - and if I were the mechanic I'd want the opportunity to fix a customer's problem with an engine I'd just rebuilt/reinstalled.