2QM15 exhaust manifold blockage

[aleggert52]

Hello Cruisers, A special thanks to Skipperpete and the people that helped me with my high pressure fuel pump in my 2QM15 engine. I finally received my new pump and installed it and the engine still will not start. I took the injectors out and re-hooked the system back up so I could see if the injectors were producing atomized fuel and they were. So I am getting fuel in the motor. I have new engine oil, new fuel filters everywhere, new hoses and no air in the fuel system as well as new diesel fuel and the air cleaner is off and still the engine will not start. I am wondering if the exhaust manifold has a blockage and could this keep the engine from starting?

[tkeithlu]

It certainly could, but let's try to think through other opportunities for a bad day. Blocking the exhaust would be a whopping big block, as in a pelican nesting in your muffler, and I would expect some firing before the exhaust backed up. A hand over the exhaust while cranking should tell you whether air is making its way through the engine.

What smoke are you getting when you crank? Pure white means atomized fuel with no firing, while black means too rich (not enough air) partial burning. No smoke suggests getting that pelican out of there.

Could there be a blockage on the intake side rather than the exhaust? It's a bit more likely, given that it is open to pelicans wanting to nest, while getting to the exhaust manifold involves going through the cylinders, which is known to endanger flying birds.

Is it possible that you have zero compression? That's quick to check as long as you have the injectors out. Not likely, but it's the remaining possibility after you've got air in, fuel in, and exhaust out in a diesel engine.

Could you have fuel being delivered at the wrong time for the cylinders, as in a massive misassembly? Not likely, but would stop everything even with the injectors squirting.

Think of it as a process going through the engine. Something is wrong somewhere along that route, with a blocked exhaust being one possibility.

[davil]

not the same engine, have a Westerbeke.

when I bought my boat could not start, drove me nuts.
Finally found the cause
Westerbeke has a shutdown manual lever to decompress to shut down the engine.
If the lever is not returned back after the engine is shutdown next time the engine will not start, drove me nuts.
Yanmar uses an electric switch, right?
Sounds like my problem.
following on tkeithlu idea of lack of compression
pulling straws out of thin air.