Yanmar 2qm15 hard start

[Baby tug]

To me it sounds like low compression , cold engine , I would put a heater and warm your engine to 75 or 80° and then see what happens .; I wouldn’t be surprise at all if the engine fired immediately . A little shot of ether not very good for your engine so just a little bit if that helps with starting and the engine continues to run you can pretty much rule out everything else . Warm your engine to 80° or more the block needs to be warm all the way through . Or just do a compression test rule that out take it from there, a simple space heater overnight will tell you if it’s a compression problem

[bony]

TinkerNZ,
Don't know if this helps, but it's worth knowing that when bleeding the fuel lines on my 2qm15 I could not simply just follow the instruction manual procedure. Before cracking the injectors to bleed the lines I first had to crack the two nuts at the front of the engine and bleed them until fuel comes out. Only then could I continue on to bleed the injectors. If I didn't do this no fuel would get to the injectors and the engine won't start. You can see a photo showing the position of the two nuts in one of my earlier posts at this link -

https://www.cruisersforum.com/forums...ml#post2241252

Another thing I found with my old 2qm15 was, with the engine not running fuel would drain back down the fuel hose to the tank. So when using the manual bleed lever the fuel pump had trouble bringing it all the way back up. I solved this by fitting one of those rubber squeeze bulbs into the line near the engine just before the fuel pump. A couple of squeezes on the bulb brings the fuel right up to the pump under pressure and the engine then has no trouble picking up the fuel.

Hope this helps.

[TinkerNZ]

So here is the update. So based on Wotname's suggestions it sounded like a injector leak or a fuel pump issue. I was suggested to get the Injectors checked first first and sure enough one of then had a leaky check valve. I had them both serviced and got them back yesterday morning. After going through the bleed procedure she started right up. I just got back from the boat, 2 seconds and away she went. No issues. I will leave it for a few days but I think that has it solved. Thank you so much for everyone's advice and a particular thank you to Wotname for going into so much detail and walking me through the basics. Now I just need to fix all the other weirdness that is this neglected engine (corroded and fused into place Thermostat) but that does not seem to effect her running, or at least not to a level I notice, so I'll put out a new post when I get around to tackling that Cheers everyone.

[Compass790]

Hi TinkerNZ. Be glad you have a 2QM15, they are much more robust than a modern Yanmar IMO. Sounds like you need a cooling galleries descale & a new engine anode. There are youtube vids on that. The exhaust mixing elbows are a common cause of problems so make sure you check that. When they fail seawater can get in the cylinders. I made my own exhaust out of 316L sched 10 ss pipe & elbows as price in NZ for a genuine Yanmar was over NZ$600.
If everything is at spec they should start straight away in +15oC temps but 2 secs aint bad.
Good tutorial you gave him Wottie

[Wotname]

Well done Tinker, glad to hear the starting problem is solved


I echo Compass790 comments. IMO, be very glad you have a 2QM15 and not the current YM series.

IMO, the QM series were built to last - as long as you maintain them.
IMO, the YM series were built for light duty only even if you maintain them.

Inspect and replace the anodes regularly, descale very occasionally and keep a weather-eye on the exhaust mixing elbow and the engine will repay you with decades of reliable running.