mdb2 turning over but won't catch

jennsea · #1 (**permalink**) 12-09-2011

I live on the wet coast and man is it cold right now! Holding the cold start will get the engine to turn over but it won't catch and just dies as soon as I release the key.
I'm new to engine maintenance and have a workshop manual which I am studying diligently, and wonder if the engine not catching (even when I hold the key in start position longer) is a sign of my injectors needing servicing or replacement? I do have a spare parts engine.

Thanks I'm advance for any advice received !

JennSea

itsaboat · #2 (**permalink**) 12-09-2011

This might not be much help, but I have an MD5B that I just bought (with a PY27 wrapped around it) with a similar problem. The previous owner said that the fuel lines sometimes get air and need to be bled. That is the first thing I will try. It was also suggested that we check the compression. After that, the injector is the most likely culprit. So my advice would be to check the less expensive things before you jump into a $400-$1000 injector job. Good luck!

PhilipStevens · #3 (**permalink**) 12-09-2011

Also check that the diaphragm in the lift pump has not split. It happened to a friend a couple of years back, and I finished up towing them to a marina to get an engineer to replace the complete lift pump (VP2003 where the lift pump has been updated to NOT be able to get into it, and no spares were available for his type - where you could change the diaphragm).

Although some fuel came out of the lift pump when manually pumped, not enough pressure was available when the engine was turned over to fire it.

Just another place to look.

My VP2003 would not fire a year or so ago, and the problem with my engine was two of the three injectors just dribbled, and the third had a weak spray. Getting the injectors serviced helped, but a further problem was low compression due to worn rings, and burnt valve seats. A complete top end overhaul and the engine started and ran perfectly.

Another place to look.

Hope you find the problem and let us know what it was.

okawbow · #4 (**permalink**) 12-09-2011

If your engine won't start well in cold weather; point a heat gun into the air intake.(with the air filter removed) Keep the hot air going until the engine is running on it's own.(a few seconds) A propane torch also works, but don't set you boat on fire

jameswilson29 · #5 (**permalink**) 12-09-2011

Quote:

Originally Posted by jennsea

Holding the cold start will get the engine to turn over...

What is the "cold start"?

I have a starter button, a glow plug button, and a kill button.

If it is cold out, the instructions recommend depressing the glow plug button for a longer period of time before attempting a start.

I doubt this could be the cause of your problem because you write that the engine does start, it just will not continue.

JimsCAL · #6 (**permalink**) 12-09-2011

Was fine before the cold snap? If so, I suspect is not something major. Make sure your batteries are fully charged. As noted, if you have them, use your glow plugs for a longer period before cranking. Another trick in cold weather is to engage the decompression levers, crank the engine to get it turning quickly, then turn the decompression levers to restore the compression and the engine should start.

jennsea · #7 (**permalink**) 12-09-2011

We have an ether cold start, no glow plug that I know of. Going to try venting the fuel line. The baby is a new beast to me, our previous boat had a lovely sabb 8 hp single cylinder that would only die if there was air in the line and had 5 bleed points vs 2 on the md2b.
Has anyone here ever used the crank start?

okawbow · #8 (**permalink**) 12-10-2011

except in an emergency. Ether with eventually damage a small diesel.

I rebuilt an Albin 2 cyl diesel earlier this year. It had been started using ether several times. It had 2 broken rings and a cracked piston.

Use the heat gun or torch. It will start a diesel if it can run at all.

jennsea · #9 (**permalink**) 12-10-2011

Quote:

Originally Posted by okawbow

If your engine won't start well in cold weather; point a heat gun into the air intake.(with the air filter removed) Keep the hot air going until the engine is running on it's own.(a few seconds) A propane torch also works, but don't set you boat on fire

Heat gun did the trick!

Still going to have the engine serviced, something that hasn't been done on this ol'girl for many years! We've only had her for a month and that was on the hard, now time to work on the mechanical!
Thanks everyone!

okawbow · #10 (**permalink**) 12-10-2011

Good to hear.

You will probably benefit from your decision to service the engine. It probably just needs the injectors cleaned or replaced, and possibly the injector timing checked. A compression test will tell you about the head gasket and piston ring condition. Also, be sure you are using the correct oil for the engine, and have good clean fuel.