Diesel woes

[JohnShannon]

What is going on? My Yanmar 1GM10 starts poorly and runs but makes no power for about 5 minutes, after which revs come up and I can motor. Is this air getting into the injection system? I basically ignore the motor until something bad happens, this is annoying and getting to the point where I could imagine something bad could happen.
Suggestions please.

 

[NYSail]

Sounds like it’s starved..... check air filter and what does exhaust / water flow look like? Might want to check mixing elbow..... start with basic stuff
Good luck!

 

[Whatfiero1]

After 5 minutes it makes power. Then shut down. And if it starts right up and makes power then definitely air getting into system. And it takes time to self bleed. Could be any fuel fitting hose or even crack in lift pump diaphragm ya need get copper washers and check every fitting hose clean engine then run looking for any fuel leeks to try find bad fitting mine was adapt fitting on top injector pump. But could be injector too. But check small stuff first cause injectors are $150 on eBay

 

[31seahorse]

With a knowing look on his weather worn face the Old Salt (or Old Fart as the case may be) said, "If the diesel engine won't run right it is either an air problem or a fuel problem."

After you check the air-related possibilities consider checking the fuel filters. (1) The one nearest to (or on) the engine. (2) The water separator filter (which probably has a paper or cartridge type filter in it too). (3) The fuel pick up tube. There is often a screen in the lower end of that tube and it can become clogged by "gunk" in the fuel tank. Checking that tube will require removing it from the fuel tank which can become an involved project. If you go to those lengths to locate/correct the problem you might as well have the fuel polished. That process will clean the fuel and also the tank's deep recesses. Best wishes.

 

[VanIslandGuy]

If you can clean the tank start there. Our old Bayfield did this, we opened the inspection port on the top and using an oil extractor sucked lots of old dead gunk off the bottom of the tank that had collected there from the previous 20 years of use prior to our purchase. Once we could only get clean diesel out we treated the tank with Startron, and switched out all of the filters. After bleeding the engine the problem was solved for us. On that boat the fuel tank was located below the engine so we added a small electric lift pump to deliver head pressure to the racor to speed up bleeding. On our Hunter we're lucky as the tank is above the engine and gravity takes care of it.

 

[MitchM]

the fact that it runs better and has power once the engine has warmed up suggests that some connection in the engine like a fuel filter cap or copper crus washer is getting a better seal with heat as the metal expands with warm engine. i'd go over all the metal to metal joints and make sure they are proper and tight. maybe a tiny bit of air is getting in with a bad primary or secondary fuel filter seal ? (did someone reuse the copper crush washer without annealing it ? )

 

[Benny17441]

Yes it looks like you may have some small air leak which becomes significant enough for a rough start and recovery during the time when the engine is in between uses. Fuel out, air in. Clean all the lines, lift pump and filters and look for fuel leaks before starting the engine as they can point to where the air may be getting in.

 

[JohnShannon]

Thanks guys, will do.

 

[capta]

Sounds more to me a metal expansion situation. Perhaps there is a small leak in the head gasket that closes as the engine warms, or a problem with the rings; same deal.
A fuel system air leak would normally not get better with time operating, only with a fuel flow increase. I'd get a compression check to be certain about the rings and head gasket.

 

[NYSail]

Back pressure from mixing elbow would do same.... open as it gets hotter.