Yanmar YSM 12 won't start

[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. She ran fine there on the shop floor.
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.

 

[kloudie1]

My best guess would be a tiny air leak between the tank and the electric pump.. I mean from the open tip of the dip tube in the tank through the top fittings, valve, hoses, and all connections.. Going to require lots of bleeding until that is corrected.
EDIT: Is that one where the return flow goes back to the secondary filter instead of tank?

 

[hapibeli]

Yes, the return flow goes back to the filter that is on the motor (secondary filter) , which is where I connected the electric fuel pump, bypassing the mechanical lift pump. Our mechanic also put a return line, from the return line at the filter, back into the tank.
I plugged off the mechanical filter to prevent any issues with oil coming from the cam on the mechanical lift pump.
I have replaced all of the fuel lines from the tank to the secondary filter as well as the new line from the secondary filter returning to the tank.

 

[JohnVTX]

I agree, air somewhere.

 

[hapibeli]

I will begin a thorough check of all of the fuel lines for leaks as soon as I check the injection pump's operation at the injector. ( having someone try starting while I crack the bolt at the injector looking for a strong squirting action). If that is incorrect, please tell me?
Thank you Kloudie 1 and JohnVTX
Cheers

 

[kloudie1]

Just a check, HapiBeli Make sure that before you crank the engine, that the primary filter is full; then turn on the electric pump and bleed to secondary filter, then to the HP pump. Any bleeding openings should be shut off with fuel still flowing so that air does not back up into the system .. then with about half throttle, crank the engine over and crack the HP connection on the injector (side connection) .. Be careful about not backing water into the engine.. if you anticipate a lot of cranking, you want to close the seacock and take the intake hose off the seawater pump. When it fires.. don't let it run more than 5 seconds before stopping it and putting the hose back on and opening the seacock.. Good Luck on the bleeding and air leak stoppage.

 

[Benny17441]

Yes, go ahead and bleed the air at the injection pump. The engine should start. After shutdown let the engine sit for 24 hours and see if it restarts freely. If it does not you have a significant leak; look for evidence of a fuel leak at the connectors, filters and the electric pump itself. (fuel leaks out when the engine running - air leaks in when the engine is stopped) . Even the bleed screw in the secondary filter is a common source of air leaks. If it restarts after 24 hours but not after 5-7 days the leak is smaller and will be harder to trace. Good luck.

 

[lee oakley]

Bleed it that is the easiest thing to do. may try a shot of ether to see if you are getting any fire but bleeding it from top to bottom is your best bet

 

[Roland5048]

Had a YSB12 in my '77 with an electric fuel pump. Very simple diesel. Simple to bleed. My guess, also, is an air leak.

 

[hapibeli]

Thanks all. It was air. She runs like a champ now!
Cheers

 

[weinie]

Is the mechanic going to give you the money back for the fuel pump he installed for no reason?

 

[hapibeli]

Oh look! A troll! So rare, and yet so refreshing to know they exist even on a boat forum…

 

[weinie]

Oh look! A troll! So rare, and yet so refreshing to know they exist even on a boat forum…

Lighten up Francis.
Apparently your mechanic installed a fuel pump unnecessarily. Am I wrong here? You don't want to ask for your money back or at least a credit of some sort for the labor? Fine. Whatever floats your boat.

 

[kito]

Oh look! A troll! So rare, and yet so refreshing to know they exist even on a boat forum…

Really nice Mr. 10 posts!

 

[kito]

Lighten up Francis.
Apparently your mechanic installed a fuel pump unnecessarily. Am I wrong here? You don't want to ask for your money back or at least a credit of some sort for the labor? Fine. Whatever floats your boat.

I have a ysm12 and had the same problem. It took 5 or 6 bleedings to get it to run smooth. Apparently the mechanic bleed his wallet instead of the fuel lines Should have been on top of the list to do before swapping out good parts.

 

[lee oakley]

Seems like someone had posted something about bleeding the lines first! Gee why ask????

 

[hapibeli]

My apologies for poor wit. My mechanic is a semi-retired marine mechanic of 70 years, with 50 years of experience, and a sterling reputation locally. He has been one of the goto mechanics and cannot satisfy all of the requests for his help.
A really nice guy who charged me $20/hour for his work, often charging less than the hours he spent, and who taught me a great deal. I now have much more confidence in my abilities due to his instruction.
True, the bleeding stumped him as he bled the system a number of times. Once I replaced all but one fuel line, removed the lift pump from the circuit, I am able to start and run her easily.
He also built a freshwater cooling system for the boat with parts he assembled, after we found the cooling jacket plugged except for one port, upon removing the engine. He also manufactured a sleeve on the alternator shaft out of a bar of bronze in his shop, as it had been damaged by the engine overheating when I first took her out last Spring 2015.
He has built over one hundred freshwater systems over the years and I requested mine as prevention for any future raw water in the motor. He built his own tractor using a VW diesel among various other useful items, for the love of it I think. Please forgive my cavalier ignorance of your earlier observations.

 

[lee oakley]

Well he sounds like a good mech. you were trying to do your best no apology needed