M25XP will not start

[justinsteele]

I know this is a topic that has been beat since I have been reading for days but Im stuck so here it is.

I just put my engine back in the boat and it will not start. Turns over no problem but will not start.

I replaced the fuel filter on the engine and bled the system from the knob on top of its housing.
My knurled knob on the side of the high pressure pump is broken off so that took me a minute to figure out but there was enough nub left that today I was able to grab it with pliers if I took the nut off and unscrew it a bit. I actually backed it off enough that fuel poured out with the primary feed pump running. I caught the fuel in a clear cup about 2oz which has a clear yellow tint to it.

I even went as far as cracking the injectors which I know everyone says isn't needed but I'm desperately frustrated. I have fuel flowing through the system and coming out through the return line at this point but the engine still will not start. It was a chilly day, upper 40's so I sat on the glow plug button for a bit, still no change.

Who has suggestions for what else I can check? I really know very little about diesels.

Muffler drain is open to prevent overflow however the raw water pump also isn't pulling anything in. Does this need to be primed after replacement somehow? Boat is on the hard I just have the intake hose in a 5gal bucket at the moment with a garden hose at the ready to replenish the supply but it hasn't sucked a drop.

[Ron Hill]

Justin : It sounds to me that you have a double problem. You need to look at the raw water pump as it should have sucked up some water without being primed. Look at the blades, the inside of the face plate should be smooth with NO grooving, the gasket should be paper thin. If you've checked all of that forget the raw water pump as the engine can run for 10? seconds with out raw water!!

Don't know what to tell you about the fuel as you've covered that. Is you decompression lever closed???

A few thoughts

[Jon W]

Hi Justin, - FWIW - a while back I couldn't get my M25XP to start. It turned over fine, and ran fine the day before. Turns out when the engine shutdown cable passed by the rudder tube it developed a tight radius bend in it for some reason. It wouldn't shift the engine lever all the way to the run position even though the handle was all the way down in the cockpit. I increased the bend radius and it was able to return the lever fully to the start position, and the engine started.

[scgunner]

Justin,

The 40s is very cold, so you sat on the glow plug for a bit. What's a bit? It's been a while since I've looked at the book but as I recall on a warm day the glow plug button should be depressed for 30 sec on a cold day it should be 60 sec. Are you sure the glow plugs are working?

The water pump is a positive pressure pump so it shouldn't need to be primed. But when I replace the impeller before I crank the motor I remove that top plug and spray WD-40 into the hole. That does two things; it lubes the impeller until the pump is primed and allows air to escape and achieve prime quicker. Don't forget to replace the plug.

One more thing, there were some defective replacement impellers, the rubber separates from the brass so it doesn't spin in the pump. I got one a while ago and it took me a while to track it down. Something you should definitely check if the pump won't prime.

[justinsteele]

Thanks Ron, I just rebuilt the pump, new impeller, seals, cover plate, o ring for the cover plate. I removed the cover to make sure it was all looking ok still yesterday and seems fine. Who knows...

Decompression is closed, I fiddled with it and tried starting in both positions to make sure I had it right.

Thanks Jon, the lever is all the way forward, I wish it was that easy, Appreciate the suggestions because it could very possibly be something very small and simple like that.

scgunner, a bit was definitely not 60 seconds and likely not 30. I'll check to make sure they are at least getting power and give them more time to do their job. Appreciate the suggestion on the pump as well. Ill remove that plug and see if that helps anything and at least them I will see water coming out when it starts working.

[justinsteele]

scgunner you were spot on. I held the glow plug button for 60 seconds and it actually made a stronger attempt. Battery was getting a little tired after all of this so I borrowed one from a friend and she fired right up. Runs beautifully, pumping water and everything. Thank you to everyone for your suggestions, I'll be back with another issue shortly I am sure!

[Ron Hill]

Justin : You need to look at the glow plug Modification in the mainsheet tech notes and the critical updates. It allows you to hit the glow plugs for 5/10 seconds.
Even without that mod. I NEVER had to hold the glow plugs for more than 10 seconds - 15 at the most!!

A few thoughts

[scgunner]

Ron,

That's what I read in the Owner's Manual under starting procedures. And as Justin just found out it's better to hold the glow plug button down too long than not long enough. I'm in SoCal so 20 to 30 works for me.

Justin,

One more thing I do when starting is to give it about 1/4 to 1/3 throttle, at that setting it fires almost instantly. Once it fires you can back the throttle down for warm up.

[Ron Hill]

Kevin : Yes, you always want to "crack" the throttle when starting the engine !!

A thought

[justinsteele]

Thank you all, New boat, never had a diesel, learning a lot.